Temperature modifies the association between particulate air pollution and mortality: A multi-city study in South Korea

Combined effects of ambient air pollution and temperature on mortality in Thailand

This study aimed to investigate the combined effects of air pollution and temperature on mortality in 34 provinces of Thailand by modeling temperature as a confounding factor and effect modifier, estimating the effects of air pollution at low, moderate, and high temperature categories defined by the 1st and 99th province-specific temperature percentiles. When the temperature was modeled as a confounding factor, the relative risk (RR) of mortality associated with a 10 µg/m3 increase in PM10 and PM2.5 (lag 0-2), and a 10-ppb increase in NO2 (lag 0-2) and O3 (lag 0-7) was respectively 1.0096 (95% Confidence Interval (CI): 1.0073, 1.0118), 1.0134 (95% CI: 1.0099, 1.0170), 1.0172 (95% CI: 1.0122, 1.0222), and 1.0164 (95% CI: 1.0093, 1.0236). Regarding temperature as an effect modifier, the combined effects of air pollution and temperature were observed as a U-shaped pattern, where the effects of PM10, PM2.5, NO2, and O3 on mortality were greater at low (< 1st percentile) and high (> 99th percentile) temperature days compared to those at moderate temperature days (1st - 99th percentile). The pattern of combined effects of air pollution and temperature remained robust even when different temperature percentiles were employed, except for that of NO2. Furthermore, the estimated effects of PM10, PM2.5, NO2, and O3 on mortality at high-temperature days were mitigated by high green density. Findings of this study revealed that extreme temperature (both hot and cold) could exacerbate the effect of air pollution on mortality, and higher green density mitigate the combined effects of air pollution and high temperature.

How do environmental and operational factors impact particulate matter dynamics in building construction? - Insights from real-time sensing

Construction activities are major contributors to particulate matter (PM) pollution, posing significant risks to workers and nearby populations. However, PM mitigation strategies in the complex nature of construction environments remain underexplored, with limited understanding of how environmental and operational factors jointly influence PM dynamics in real-world settings. This study employs high-resolution real-time monitoring to investigate PM1, PM2.5, and PM10 interactions within an active construction site, focusing on the roles of environmental and operational drivers. Over 28,000 measurements were collected from construction zones, complemented by external reference points. The findings reveal that smaller particles (PM1 and PM2.5) serve as critical intermediaries influencing larger particles (PM10). PM10 concentrations peaked at 1763.37 μg/m3, far exceeding regulatory thresholds. Temperature influenced PM10 primarily through its effect on PM2.5 (57 %), while construction scenarios had 72 % of their impact on PM10 mediated via PM2.5. Distinct PM relationships emerged based on activity types and worker proximity to sensors, with hazardous PM levels persisting in 81.61 % of low-activity periods, highlighting the risks of residual exposure even without active construction. This study underscores the importance of on-site, multi-indicator monitoring systems to capture dynamic PM variations and identify high-risk scenarios. By providing a detailed understanding of PM interactions in active construction settings, these findings offer a robust foundation for developing targeted mitigation strategies and advancing air quality management in construction environments.

Climate change effects in older people's health: A scoping review

BACKGROUND

Climate change has serious consequences for the morbidity and mortality of older adults.

OBJECTIVE

To identify the effects of climate change on older people's health.

METHODS

A scoping review was conducted following the Joanna Briggs Institute guidelines and the PRISMA-ScR checklist. Quantitative research and reports from organizations describing the effects of climate change on older people were selected.

RESULTS

Sixty-three full-text documents were selected. Heat and air pollution were the two factors that had the most negative effects on cardiovascular and respiratory morbidity and mortality in older people. Mental health and cognitive function were also affected.

CONCLUSIONS

Climate change affects several health problems in older individuals, especially high temperatures and air pollution. Nursing professionals must have the necessary skills to respond to the climate risks in older adults. More instruments are required to determine nursing competencies on climate change and the health of this population group.

PATIENT OF PUBLIC CONTRIBUTION

No patient or public contribution.

Exposure to Concurrent Heatwaves and Ozone Pollution and Associations with Mortality Risk: A Nationwide Study in China

BACKGROUND

Concurrent extreme events are projected to occur more frequently under a changing climate. Understanding the mortality risk and burden of the concurrent heatwaves and ozone (O 3 ) pollution may support the formulation of adaptation strategies and early warning systems for concurrent events in the context of climate change.

OBJECTIVES

We aimed to estimate the mortality risk and excess deaths of concurrent heatwaves and O 3 pollution across 250 counties in China.

METHODS

We collected daily mortality, meteorological, and air pollution data for the summer (1 June to 30 September) during 2013-2018. We defined heatwaves and high O 3 pollution days, then we divided the identified days into three categories: a) days with only heatwaves (heatwave-only event), b) days with only high O 3 pollution (high O 3 pollution-only event), and c) days with concurrent heatwaves and high O 3 pollution (concurrent event). A generalized linear model with a quasi-Poisson regression was used to estimate the risk of mortality associated with extreme events for each county. Then we conducted a random-effects meta-analysis to pool the county-specific estimates to derive the overall effect estimates. We used mixed-effects meta-regression to identify the drivers of the heterogeneity. Finally, we estimated the excess death attributable to extreme events (heatwave-only, high O 3 pollution-only, and concurrent events) from 2013 to 2020.

RESULTS

A higher all-cause mortality risk was associated with exposure to the concurrent heatwaves and high O 3 pollution than exposure to a heatwave-only or a high O 3 pollution-only event. The effects of a concurrent event on circulatory and respiratory mortality were higher than all-cause and nonaccidental mortality. Sex and age significantly impacted the association of concurrent events and heatwave-only events with all-cause mortality. We estimated that annual average excess deaths attributed to the concurrent events were 6,249 in China from 2017 to 2020, 5.7 times higher than the annual average excess deaths attributed to the concurrent events from 2013 to 2016. The annual average proportion of excess deaths attributed to the concurrent events in the total excess deaths caused by three types of events (heatwave-only events, high O 3 pollution-only events, and concurrent events) increased significantly in 2017-2020 (31.50%; 95% CI: 26.73%, 35.53%) compared with 2013-2016 (9.65%; 95% CI: 5.67%, 10.81%). Relative excess risk due to interaction revealed positive additive interaction considering the concurrent effect of heatwaves and high O 3 pollution.

DISCUSSION

Our findings may provide scientific basis for establishing a concurrent event early warning system to reduce the adverse health impact of the concurrent heatwaves and high O 3 pollution. https://doi.org/10.1289/EHP13790.

Enhancing health resilience in Japan in a changing climate

Climate change poses significant threats to human health, propelling Japan to take decisive action through the Climate Change Adaptation Act of 2018. This Act has led to the implementation of climate change adaptation policies across various sectors, including healthcare. In this review, we synthesized existing scientific evidence on the impacts of climate change on health in Japan and outlined the adaptation strategies and measures implemented by the central and local governments. The country has prioritized tackling heat-related illness and mortality and undertaken various adaptation measures to mitigate these risks. However, it faces unique challenges due to its super-aged society. Ensuring effective and coordinated strategies to address the growing uncertainties in vulnerability to climate change and the complex intersectoral impacts of disasters remains a critical issue. To combat the additional health risks by climate change, a comprehensive approach embracing adaptation and mitigation policies in the health sector is crucial. Encouraging intersectoral communication and collaboration will be vital for developing coherent and effective strategies to safeguard public health in the face of climate change.

The interactive effects of extreme temperatures and PM2.5 pollution on mortalities in Jiangsu Province, China

Exposure to extreme temperatures or fine particles is associated with adverse health outcomes but their interactive effects remain unclear. We aimed to explore the interactions of extreme temperatures and PM2.5 pollution on mortalities. Based on the daily mortality data collected during 2015-2019 in Jiangsu Province, China, we conducted generalized linear models with distributed lag non-linear model to estimate the regional-level effects of cold/hot extremes and PM2.5 pollution. The relative excess risk due to interaction (RERI) was evaluated to represent the interaction. The relative risks (RRs) and cumulative relative risks (CRRs) of total and cause-specific mortalities associated with hot extremes were significantly stronger (p < 0.05) than those related to cold extremes across Jiangsu. We identified significantly higher interactions between hot extremes and PM2.5 pollution, with the RERI range of 0.00-1.15. The interactions peaked on ischaemic heart disease (RERI = 1.13 [95%CI: 0.85, 1.41]) in middle Jiangsu. For respiratory mortality, RERIs were higher in females and the less educated. The interaction pattern remained consistent when defining the extremes/pollution with different thresholds. This study provides a comprehensive picture of the interactions between extreme temperatures and PM2.5 pollution on total and cause-specific mortalities. The projected interactions call for public health actions to face the twin challenges, especially the co-appearance of hot extremes and PM pollution.

Temperature modifies the effects of air pollutants on respiratory diseases

Increasing studies have reported temperature modification effects on air pollutants-induced respiratory diseases. In the current study, daily data of respiratory emergency room visits (ERVs), meteorological factors, and concentrations of air pollutants were collected from 2013 to 2016 in Lanzhou, a northwest city in China. Daily average temperature was stratified into low (≤ 25 percentile, P₂₅), medium (25-75 percentile, P₂₅-P₇₅) and high (≥ 75 percentile, P₇₅) to explore how temperature modifies the effects of air pollutants (PM_2.5, PM₁₀, SO₂, and NO₂) on respiratory ERVs by using generalized additive Poisson regression model (GAM). Seasonal modification was also investigated. Results showed that (a) PM₁₀, PM_2.5, and NO₂ had the strongest effects on respiratory ERVs in low temperature; (b) males and 15-and-younger were more vulnerable in low temperature while females and those older than 46 years were highly affected in high temperature; (c) PM₁₀, PM_2.5, and NO₂ were mostly associated with the total and both males and females in winter, while SO₂ resulted in the highest risk for the total and males in autumn and females in spring. In conclusion, this study found significant temperature modification effects and seasonal differences on the risks of respiratory ERVs due to air pollutants in Lanzhou, China.

A Multi-Pollutant and Meteorological Analysis of Cardiorespiratory Mortality among the Elderly in São Paulo, Brazil-An Artificial Neural Networks Approach

Traditionally, studies that associate air pollution with health effects relate individual pollutants to outcomes such as mortality or hospital admissions. However, models capable of analyzing the effects resulting from the atmosphere mixture are demanded. In this study, multilayer perceptron neural networks were evaluated to associate PM₁₀, NO₂, and SO₂ concentrations, temperature, wind speed, and relative air humidity with cardiorespiratory mortality among the elderly in São Paulo, Brazil. Daily data from 2007 to 2019 were considered and different numbers of neurons on the hidden layer, algorithms, and a combination of activation functions were tested. The best-fitted artificial neural network (ANN) resulted in a MAPE equal to 13.46%. When individual season data were analyzed, the MAPE decreased to 11%. The most influential variables in cardiorespiratory mortality among the elderly were PM₁₀ and NO₂ concentrations. The relative humidity variable is more important during the dry season, and temperature is more important during the rainy season. The models were not subjected to the multicollinearity issue as with classical regression models. The use of ANNs to relate air quality to health outcomes is still very incipient, and this work highlights that it is a powerful tool that should be further explored.

Effect modification by temperature on the association between O3 and emergency ambulance dispatches in Japan: A multi-city study

Numerous epidemiological studies have reported that ozone (O₃) and temperature are independently associated with health outcomes, but modification of the effects of O₃ on health outcomes by temperature, and vice versa, has not been fully described. This study aimed to investigate effect modification by temperature on the association between O₃ and emergency ambulance dispatches (EADs) in Japan. Data on daily air pollutants, ambient temperature, and EADs were obtained from eight Japanese cities from 2007 to 2015. A distributed lag non-linear model combined with Poisson regression was performed with temperature as a confounding factor and effect modifier to estimate the effects of O₃ on EADs at low (<25th percentile), moderate (25th-75th percentile), and high (>75th percentile) temperature for each city. The estimates obtained from each city were pooled by random-effects meta-analysis. When temperature was entered as a confounder, the estimated effects of O₃ on EADs for all acute, cardiovascular, and respiratory illnesses were largest at lag 0 (current-day lag). Therefore, this lag was used to further estimate the effects of O₃ on EADs in each temperature category. The estimated effects of O₃ on EADs for all acute, cardiovascular, and respiratory illnesses in all eight Japanese cities increased with increasing temperature. Specifically, a 10 ppb increase in O₃ was associated with 0.80 % (95 % CI: 0.25 to 1.35), 0.19 % (95 % CI: -0.85 to 1.25), and 1.14 % (95 % CI: -0.01 to 2.31) increases in the risk of EADs for all acute, cardiovascular, and respiratory illnesses, respectively, when city-specific daily temperature exceeded the 75th percentile. Our findings suggest that the association between O₃ and EADs for all acute, cardiovascular, and respiratory illnesses is the highest during high temperature. Finding of this study can be used to develop potential mitigation measures against O₃ exposure in high temperature environment to reduce its associated adverse health effects.

Air Pollution and Public Bike-Sharing System Ridership in the Context of Sustainable Development Goals

A bicycle-sharing system (BSS) has been implemented in Seoul, South Korea to promote green transportation policy as a Sustainable Development Goal (SDG) to mitigate climate change, reduce traffic jams, and promote physical activity. However, the concentration of air pollutants in Seoul often exceeds the standards of the World Health Organization, thereby creating a conflict with SDG 3 (Health). Therefore, it is important to recognize the trade-offs between actions targeted at SDGs as they might offset each other. In this context, a primary concern is investigating how the behavior of BSS users regarding outdoor air pollution appears. This study explores the relationship between ambient air pollution and the behavior of BSS riders in Seoul. We conducted a time-series analysis of associations between particulate air pollution and participation in the BSS. We used generalized additive models, adjusted for mean temperature, humidity, rainfall, day of the week, long-term trends, and seasonality to construct an exposure–response relationship. We observed a nonlinear relationship between increasing air pollution and bicycle ridership. This study method can be used as a basis for similar analyses to investigate BSS policies in other cities.

Combined effects of air pollution and extreme heat events among ESKD patients within the Northeastern United States

BACKGROUND

Increasing number of studies have linked air pollution exposure with renal function decline and disease. However, there is a lack of data on its impact among end-stage kidney disease (ESKD) patients and its potential modifying effect from extreme heat events (EHE).

METHODS

Fresenius Kidney Care records from 28 selected northeastern US counties were used to pool daily all-cause mortality (ACM) and all-cause hospital admissions (ACHA) counts. County-level daily ambient PM_2.5 and ozone (O₃) were estimated using a high-resolution spatiotemporal coupled climate-air quality model and matched to ESKD patients based on ZIP codes of treatment sites. We used time-stratified case-crossover analyses to characterize acute exposures using individual and cumulative lag exposures for up to 3 days (Lag 0-3) by using a distributed lag nonlinear model framework. We used a nested model comparison hypothesis test to evaluate for interaction effects between air pollutants and EHE and stratification analyses to estimate effect measures modified by EHE days.

RESULTS

From 2001 to 2016, the sample population consisted of 43,338 ESKD patients. We recorded 5217 deaths and 78,433 hospital admissions. A 10-unit increase in PM_2.5 concentration was associated with a 5% increase in ACM (rate ratio [RR_Lag0-3]: 1.05, 95% CI: 1.00-1.10) and same-day O₃ (RR_Lag0: 1.02, 95% CI: 1.01-1.03) after adjusting for extreme heat exposures. Mortality models suggest evidence of interaction and effect measure modification, though not always simultaneously. ACM risk increased up to 8% when daily ozone concentrations exceeded National Ambient Air Quality Standards established by the United States, but the increases in risk were considerably higher during EHE days across lag periods.

CONCLUSION

Our findings suggest interdependent effects of EHE and air pollution among ESKD patients for all-cause mortality risks. National level assessments are needed to consider the ESKD population as a sensitive population and inform treatment protocols during extreme heat and degraded pollution episodes.

Long-Term Air Pollution Exposure and Ischemic Heart Disease Mortality Among Elderly in High Aging Asian Economies

In the epidemiological literature, the impact of environmental pollution on cardiac mortality has been well documented. There is, however, a paucity of evidence on the impact of air pollution exposure on ischemic heart disease (IHD) mortality among the Asian aged population. In response, this research seeks to investigate the degree of proximity between exposure to ambient PM2.5, household PM2.5, ground-level ozone (O3), and IHD mortality in the top seven Asian economies with the highest aging rates. This investigation is held in two phases. In the first phase, grey modeling is employed to assess the degree of proximity among the selected variables, and then rank them based on their estimated grey weights. In addition, a grey-based Technique for Order of Preference by Similarity to Ideal Solution (G-TOPSIS) is adopted to identify the key influencing factor that intensifies IHD mortality across the selected Asian economies. According to the estimated results, South Korea was the most afflicted nation in terms of IHD mortality owing to ambient PM2.5 and ground-level O3 exposure, whereas among the studied nations India was the biggest contributor to raising IHD mortality due to household PM2.5 exposure. Further, the outcomes of G-TOPSIS highlighted that exposure to household PM2.5 is a key influencing risk factor for increased IHD mortality in these regions, outweighing all other air pollutants. In conclusion, this grey assessment may enable policymakers to target more vulnerable individuals based on scientific facts and promote regional environmental justice. Stronger emission regulations will also be required to mitigate the adverse health outcomes associated with air pollution exposure, particularly in regions with a higher elderly population.

Short-term effects of ambient air pollution and meteorological factors on tuberculosis in semi-arid area, northwest China: a case study in Lanzhou

To investigate the short-term effects of ambient air pollution and meteorological factors on daily tuberculosis (TB), semi-parametric generalized additive model was used to assess the impacts of ambient air pollutants and meteorological factors on daily TB case from 2005 to 2010 in Chengguan District, Lanzhou, China. Then a non-stratification parametric model and a stratification parametric model were applied to study the interactive effect of air pollutants and meteorological factors on daily TB. The results show that sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and particulate matter with aerodynamic diameter less than 10μm (PM₁₀) were positively correlated with daily TB case; the excess risk (ER) and 95% confidence interval (CI) were 1.79% (0.40%, 3.20%), 3.86% (1.81%, 5.96%), and 0.32% (0.02%, 0.62%), respectively. Daily TB case was positively correlated with maximum temperature, minimum temperature, average temperature, vapor pressure, and relative humidity, but negatively correlated with atmospheric pressure, wind speed, and sunshine duration. The association with average temperature was the strongest, whose ER and 95% CI were 4.43% (3.15%, 5.72%). In addition, there were significant interaction effects between air pollutants and meteorological factors on daily TB case.

Suicide and Associations with Air Pollution and Ambient Temperature: A Systematic Review and Meta-Analysis

Given health threats of climate change, a comprehensive review of the impacts of ambient temperature and ar pollution on suicide is needed. We performed systematic literature review and meta-analysis of suicide risks associated with short-term exposure to ambient temperature and air pollution. Pubmed, Scopus, and Web of Science were searched for English-language publications using relevant keywords. Observational studies assessing risks of daily suicide and suicide attempts associated with temperature, particulate matter with aerodynamic diameter ≤10 μm (PM₁₀) and ≤2.5 mm (PM_2.5), ozone (O₃), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and carbon monoxide (CO) were included. Data extraction was independently performed in duplicate. Random-effect meta-analysis was applied to pool risk ratios (RRs) for increases in daily suicide per interquartile range (IQR) increase in exposure. Meta-regression analysis was applied to examine effect modification by income level based on gross national income (GNI) per capita, national suicide rates, and average level of exposure factors. In total 2274 articles were screened, with 18 studies meeting inclusion criteria for air pollution and 32 studies for temperature. RRs of suicide per 7.1 °C temperature was 1.09 (95% CI: 1.06, 1.13). RRs of suicide per IQR increase in PM_2.5, PM₁₀, and NO₂ were 1.02 (95% CI: 1.00, 1.05), 1.01 (95% CI: 1.00, 1.03), and 1.03 (95% CI: 1.00, 1.07). O₃, SO₂, and CO were not associated with suicide. RR of suicide was significantly higher in higher-income than lower-income countries (1.09, 95% CI: 1.07, 1.11 and 1.20, 95% CI: 1.14, 1.26 per 7.1 °C increased temperature, respectively). Suicide risks associated with air pollution did not significantly differ by income level, national suicide rates, or average exposure levels. Research gaps were found for interactions between air pollution and temperature on suicide risks.

Combined Effect of Hot Weather and Outdoor Air Pollution on Respiratory Health: Literature Review

Association between short-term exposure to ambient air pollution and respiratory health is well documented. At the same time, it is widely known that extreme weather events intrinsically exacerbate air pollution impact. Particularly, hot weather and extreme temperatures during heat waves (HW) significantly affect human health, increasing risks of respiratory mortality and morbidity. Concurrently, a synergistic effect of air pollution and high temperatures can be combined with weather–air pollution interaction during wildfires. The purpose of the current review is to summarize literature on interplay of hot weather, air pollution, and respiratory health consequences worldwide, with the ultimate goal of identifying the most dangerous pollution agents and vulnerable population groups. A literature search was conducted using electronic databases Web of Science, Pubmed, Science Direct, and Scopus, focusing only on peer-reviewed journal articles published in English from 2000 to 2021. The main findings demonstrate that the increased level of PM10 and O3 results in significantly higher rates of respiratory and cardiopulmonary mortality. Increments in PM2.5 and PM10, O3, CO, and NO2 concentrations during high temperature episodes are dramatically associated with higher admissions to hospital in patients with chronic obstructive pulmonary disease, daily hospital emergency transports for asthma, acute and chronic bronchitis, and premature mortality caused by respiratory disease. Excessive respiratory health risk is more pronounced in elderly cohorts and small children. Both heat waves and outdoor air pollution are synergistically linked and are expected to be more serious in the future due to greater climate instability, being a crucial threat to global public health that requires the responsible involvement of researchers at all levels. Sustainable urban planning and smart city design could significantly reduce both urban heat islands effect and air pollution.

Short-term exposure to air pollution and hospital admission for heart failure among older adults in metropolitan cities: a time-series study

PURPOSE

We aimed to investigate the association between air pollution concentration levels and hospital admissions for heart failure (HF) among older adults in metropolitan cities in South Korea.

METHODS

We used hospital admission data of 1.8 million older adults in seven metropolitan cities from 2008 to 2016, derived from the National Health Insurance Service of South Korea. Daily HF admission data were linked to air pollutants concentrations for the respective dates, including particulate matter less than 2.5 μm in size (PM_2.5), 10 μm (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone. We estimated the association between air pollutants and daily HF admissions using quasi-Poisson generalized additive models for each city.

RESULTS

During the study period, 142,490 hospital admissions for HF were noted. Increases of 10 μg/m³ of PM_2.5 and PM₁₀, and 10 ppb of SO₂, NO₂, and CO were associated with an increased risk of HF admission by 0.93% ([95% confidence intervals 0.51-1.36], 0.55% [0.31-0.80], 6.04% [2.15-10.08], 1.10% [0.38-1.82], and 0.05% [0.01-0.09]), respectively, on the same day. Increases in mean exposure to PM_2.5, PM₁₀, and SO₂ for 8 days from the concurrent day were also significantly associated with HF admissions. During the warm season, the risk of HF admissions increased shortly after an increase in PM_2.5, whereas prolonged effects were observed during the cold season.

CONCLUSION

Our study suggests the adverse effects of air pollution on HF. Moreover, the evidence of seasonality may help tailor protection guidelines for older adults.

Climatic modification effects on the association between PM1 and lung cancer incidence in China

Background

Nationwide studies that examine climatic modification effects on the association between air pollution and health outcome are limited in developing countries. Moreover, few studies focus on PM1 pollution despite its greater health effect.

Objectives

This study aims to determine the modification effects of climatic factors on the associations between PM1 and the incidence rates of lung cancer for males and females in China.

Methods

We conducted a nationwide analysis in 345 Chinese counties (districts) from 2014 to 2015. Mean air temperature and relative humidity over the study period were used as the proxies of climatic conditions. In terms of the multivariable linear regression model, we examined climatic modification effects in the stratified and combined datasets according to the three-category and binary divisions of climatic factors. Moreover, we performed three sensitivity analyses to test the robustness of climatic modification effects.

Results

We found a stronger association between PM1 and the incidence rate of male lung cancer in counties with high levels of air temperature or relative humidity. If there is a 10 μg/m³ shift in PM1, then the change in male incidence rate relative to its mean was higher by 4.39% (95% CI: 2.19, 6.58%) and 8.37% (95% CI: 5.18, 11.56%) in the middle and high temperature groups than in the low temperature group, respectively. The findings of climatic modification effects were robust in the three sensitivity analyses. No significant modification effect was discovered for female incidence rate.

Conclusions

Male residents in high temperature or humidity counties suffer from a larger effect of PM1 on the incidence rate of lung cancer in China. Future research on air pollution-related health impact assessment should consider the differential air pollution effects across different climatic conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10912-8.

Associations between PM1 exposure and daily emergency department visits in 19 hospitals, Beijing

Although the adverse health effects caused by PM_2.5 (particulate matter (PM) with an aerodynamic diameter <2.5 μm) and PM₁₀ (PM with an aerodynamic diameter <10 μm) have been examined in numeric studies, far less scientific evidence is available for PM with an aerodynamic diameter <1 μm (PM₁). We performed a time series analysis to elucidate the associations between PM₁ exposure and emergency department visits (EDVs) in 19 hospitals within Beijing. During the study period from January 2016 to December 2017, the average PM₁ (mean ± standard deviation) was determined to be 39 ± 39 μg/m³, which was approximately 36% lower than that of 61 ± 56 μg/m³ for PM_2.5. Results based on meta-analysis suggest that non-accidental and respiratory EDVs increased by 0.47% (95% confidence interval, CI: 0.35, 0.59%) and 0.59% (95%CI: 0.38, 0.8%) per 10 μg/m³ uptick in PM₁ exposure. By comparison, the magnitude downgraded to 0.27% (95%CI: 0.15, 0.39%) in non-accidental and 0.32% (95%CI: 0.18, 0.47%) in respiratory EDVs for PM_2.5 exposure, indicating that PMs of a smaller size may be a higher risk factor for EDVs. No significant differences in PM-associated EDV effects were noted between males and females, while stratified analysis by age and season illustrated that stronger effects were found for a warm season and young population. Our analysis reinforces the notion that PM₁ exhibited a higher risk for EDVs, suggesting more efforts may be required to mitigate PM₁ pollution.

The impact of main air pollutants on respiratory emergency department visits and the modification effects of temperature in Beijing, China

Research indicates that air pollution is a risk factor of an increased occurrence of diseases. However, evidence is limited on the effects of the pollution index on disease and whether temperature modifies the effects. The objectives were (i) to explore the effects of the Air Pollution Index (API) and specific indices for pollutants (PM₁₀, NO₂, and SO₂) on respiratory emergency department (ED) visits in Beijing and (ii) to investigate whether temperature modified the effects of main air pollutants on respiratory ED visits. A quasi-Poisson generalized additive model was employed to examine the association of API and indices for pollutants with respiratory disease. Bivariate response surface model and stratification model (cold days, moderately cold days, moderately hot days, and hot days) were used to analyze the modification effects of temperature on air pollution and respiratory disease. The results showed that (i) the effects of API on respiratory diseases were similar to the index for PM₁₀ in Beijing. (ii) API and PM₁₀ were associated with increased respiratory ED visits on cold days and moderately cold days. Furthermore, the effects of PM₁₀ on respiratory disease on moderately cold days [Relative risk (RR) = 1.006 per 10 μg/m³, 95% CI 1.002-1.009] were stronger than on cold days (RR = 1.004 per 10 μg/m³, 95% CI 1.000-1.008). (iii) PM₁₀ (API) had a greater impact on children aged 10 to 17 years and females on moderately cold days, while the elderly had an increased risk of respiratory disease to PM₁₀ (RR = 1.008 per 10 μg/m³, 95% CI 1.002-1.013) and API (RR = 1.013 per 10, 95% CI 1.004-1.022) on cold days. In conclusion, temperature can modify the association between API and respiratory morbidity. A stronger correlation existed between PM₁₀ and respiratory diseases on moderately cold days, while the effects of cold days were less than that attributable to moderately cold days.

Synergistic health effects of air pollution, temperature, and pollen exposure: a systematic review of epidemiological evidence

BACKGROUND

Exposure to heat, air pollution, and pollen are associated with health outcomes, including cardiovascular and respiratory disease. Studies assessing the health impacts of climate change have considered increased exposure to these risk factors separately, though they may be increasing simultaneously for some populations and may act synergistically on health. Our objective is to systematically review epidemiological evidence for interactive effects of multiple exposures to heat, air pollution, and pollen on human health.

METHODS

We systematically searched electronic literature databases (last search, April 29, 2019) for studies reporting quantitative measurements of associations between at least two of the exposures and mortality from any cause and cardiovascular and respiratory morbidity and mortality specifically. Following the Navigation Guide systematic review methodology, we evaluated the risk of bias of individual studies and the overall quality and strength of evidence.

RESULTS

We found 56 studies that met the inclusion criteria. Of these, six measured air pollution, heat, and pollen; 39 measured air pollution and heat; 10 measured air pollution and pollen; and one measured heat and pollen. Nearly all studies were at risk of bias from exposure assessment error. However, consistent exposure-response across studies led us to conclude that there is overall moderate quality and sufficient evidence for synergistic effects of heat and air pollution. We concluded that there is overall low quality and limited evidence for synergistic effects from simultaneous exposure to (1) air pollution, pollen, and heat; and (2) air pollution and pollen. With only one study, we were unable to assess the evidence for synergistic effects of heat and pollen.

CONCLUSIONS

If synergistic effects between heat and air pollution are confirmed with additional research, the health impacts from climate change-driven increases in air pollution and heat exposure may be larger than previously estimated in studies that consider these risk factors individually.

Ambient fine particulate matter pollution and years of life lost from cardiovascular diseases in 48 large Chinese cities: Association, effect modification, and additional life gain

Existing evidence on the associations between fine particulate matter (PM_2.5) and years of life lost (YLL) from cardiovascular diseases (CVD) is limited and inconclusive, and the role of potential modifiers, especially those at city-level, is not fully understood. In this study, a time-series study was conducted in 48 large Chinese cities from 2013 to 2017. Generalized additive model coupled with random effects model were used to estimate national-average associations of PM_2.5 with YLL. Effect modification by individual- and city-level characteristics obtained by linking with China Chronic Disease and Risk Factors Surveillance was explored. Moreover, additional life gain was evaluated under scenario where PM_2.5 concentration would be reduced. For 10 μg/m³ increase in PM_2.5 concentration at lag01 day, the relative increment of YLL was 0.22% from CVD, 0.20% from ischemic heart disease, 0.26% from stroke, 0.23% from hemorrhagic stroke, and 0.31% from ischemic stroke. Some associations were stronger in elder and less educated people, warm season, as well as cities characterized by higher temperature and prevalence of binge drinking and excess red meat intake, or lower PM_2.5 and prevalence of usual exercise. Additional life gain attributable to avoidable YLL from CVD was estimated to be 0.08 year if PM_2.5 concentration could fall to the standard recommended by World Health Organization (25 μg/m³). This large epidemiological investigation demonstrated robust evidence of short-term associations between PM_2.5 exposure and YLL from CVD. Potential modifiers should be considered to develop efficient intervention strategies. Implementation of more stringent standard is beneficial to alleviate YLL caused by PM_2.5.

Years of life lost with premature death due to ambient temperatures in a southwest plateau region of China: a cause-specific and individual characteristics stratified mortality study

We aimed to explore whether there were cold and heat temperature adverse effects on years of life lost (YLL) for non-accidental mortality in Yuxi, a southwest plateau region of China. From data for 89,467 non-accidental deaths over an 8-year study period, we used a general linear regression model combined with a distributed lag non-linear model to assess the burden of disease non-accidental mortality due to ambient temperature with the YLL indicator. We estimated the mean YLL change per 1 °C decrease from the 25th to 1st percentile mean temperature as the cold effect and per 1 °C increase from the 75th to 99th percentile as the heat effect. The 95% empirical confidence intervals (eCIs) were calculated by using a bootstrap simulation method. The exposure-response curve between average temperature and YLL was U-shaped. The cold effect peaked at the first day after exposure and disappeared at 2 weeks, and the heat effect only lasted for the first 3 days. A per 1 °C decrease from the 25th to 1st mean temperature percentile was associated with an increase of 15.6 (95% eCI: 2.4, 22.9) in YLL for non-accidental diseases, and the cumulative effects due to cold were stronger in contrast to that attributed by heat. Cold temperature had a significant impact on YLL among the subgroups, with higher YLL in cardiovascular disease, stroke, males, Han nationality, married, and those engaged in agriculture than their corresponding categories. An increasing death burden of non-accidental in Yuxi of China due to cold temperature was demonstrated, and the association was also modified by specific disease causes and individual features.

The Gender-Based Differences in Vulnerability to Ambient Air Pollution and Cerebrovascular Disease Mortality: Evidences Based on 26781 Deaths

The gender-based differences in the vulnerability to ambient air pollution have not been widely explored. This study aimed to investigate vulnerability differences to the short-term effects of PM2.5, PM10 and O3 between cerebrovascular diseases (CEVD) deaths of men and women. The general additive models (GAMs) and distributed lag non-linear models (DLNMs) were adopted, and both single-pollutant and two-pollutant models were performed to analyze the associations between ambient air pollution and daily CEVD deaths. Both models indicated that O3 was the most suspicious pollutant that could induce excess CEVD deaths, and women tended to be more vulnerable to O3. These results were confirmed by seasonal analysis, in which we also found both genders were more vulnerable to O3 in winter. The exposure-response relationships revealed that women were usually more vulnerable to ambient air pollution than men, and the exposure-response curves differed significantly between genders. Our findings suggested that more attention should be paid on the adverse effects of ambient O3, and the protection of women CEVD population against air pollution should be emphasized.

Temperature modulation of the adverse consequences on human mortality due to exposure to fine particulates: A study of multiple cities in China

Exposure to particulate matter of smaller than 2.5 μm in diameter (PM_2.5) is linked to increased human mortality, and could be further complicated by concurrent ambient air temperatures. Published reports indicate that the association between ambient temperatures and mortality due to PM_2.5 exposure is dissimilar across different geographic areas. Thus, it is unclear how ambient temperatures at different geographic locations can together modulate the influence of PM_2.5 on mortality. In this paper, we examined how temperature modulated the association between mortality and PM_2.5 exposure in 15 Chinese cities during 2014-2016. For analysis, First, Poisson generalized additive models under different temperature stratifications (<10th, 10-90th, and >90th temperature percentiles) was used to estimate PM_2.5 associations to mortality, which were specific to different cities. Second, we used a meta-analysis to combine the effects at each temperature stratum and region (southern and northern China). Results revealed that high temperatures (daily mean temperature >90th percentile) robustly amplified observed associations of mortality and PM_2.5 exposure, and the modifications were heterogeneous geographically. In the northern regions, a 10 μg/m³ increment in PM_2.5 was associated with 0.18%, 0.28%, and 1.54% increase in non-accidental mortalities and 0.33%, 0.39%, and 1.32% increase in cardiovascular mortalities at low, moderate, and high temperature levels, respectively. In the southern regions, a 10 μg/m³ increment in PM_2.5 was associated with 0.52%, 0.62%, and 1.90% increase in non-accidental mortalities and 0.55%, 0.98%, and 2.25% increase in cardiovascular mortalities at low, moderate, and high temperature levels, respectively. It is concluded that temperature altered PM_2.5-mortality associations in southern and northern China synergistically, but the effect was more pronounced in the south. Therefore, geography and temperature need to be considered when studying how PM_2.5 affects health.

Developing Vulnerability Index to Quantify Urban Heat Islands Effects Coupled with Air Pollution: A Case Study of Camden, NJ

Extreme heat events at urban centers in combination with air pollution pose a serious risk to human health. Among these are financially distressed cities and neighborhoods that are facing enormous challenges without the scientific and technical capacity for planning and mitigation. The city of Camden is one of those economically distressed areas with a predominantly minority population, a high unemployment rate, high poverty rates, and poor air quality (PM2.5 and ozone), and it remains vulnerable to heat events. This paper focuses on studying a coupled effect of Urban Heat Islands (UHIs) and Ozone-PM2.5 pollution at the neighborhood-scale in the city of Camden, using fine scale remotely sensed land-surface temperature and air quality data from the Community Multiscale Air Quality (CMAQ) Modelling System in the Geographic Information Systems (GIS) platform. To assess the impact of urban microclimate on the city of Camden, NJ, residents’ health, we identified several environmental and social parameters as the root causes of vulnerability imposed by extreme-heat and poor air quality. Vulnerability in terms of environment and social wellbeing was spatially quantified as two conceptual vulnerability-index models (i.e., environmental vulnerability index (EVI) and a social vulnerability index (SVI)) using multiple linear regression algorithm. Factors such as remotely sensed earth surface properties, built-environment components, air quality, and socio-economic data were incorporated in a holistic geographic approach to quantify the combined effect. Surface temperature gradient and Proportional Vegetation (Pv) generated from 30 m resolution Landsat 8 were sampled along with other variables in the city of Camden, NJ. Models incorporating Pv suggest better fit than models with normalized difference vegetation index (NDVI). Water fraction (33.5%, 32.4%), percentage imperviousness (32.5%, 32%), Pv (20.5%, 19.6%), and digital elevation model (DEM) (9%, 8%) have the highest contributions in both models. Two output maps identified the vulnerable neighborhoods in the city through comprehensive GIS analysis: Lanning Square, Bergen Square, Central Waterfront, Gateway, Liberty Park, and Parkside. This can provide useful information for planners and health officials in targeting areas for future interventions and mitigations.

Temperature as a modifier of the effects of air pollution on cardiovascular disease hospital admissions in Cape Town, South Africa

Climate change and air pollution are two independent risk factors to cardiovascular diseases (CVD). Few studies investigated their interaction and potential effect modification of one another in developing countries. Individual level CVD hospital admission (ICD10: I00-I99) data for 1 January 2011 to 31 October 2016 were obtained from seven private hospitals in Cape Town. NO₂, SO₂, PM₁₀, temperature and relative humidity data were obtained from the South African Weather Services and the City of Cape Town. A case-crossover epidemiological study design and conditional logistic regression model were applied. Various cut-off values were applied to classify cold and warm days. In total, 54,818 CVD hospital admissions were included in the study. In general, on warm and cold days the 15-64 years old group was more at risk for CVD hospitalization with increasing air pollution levels compared to all ages combined or the ≥ 65 years old group. Females appeared to be more at risk than males with increasing PM₁₀ levels. In contrast, males were more vulnerable to the effects of NO₂ and SO₂ than females. The study showed the modification effect of temperature on air pollution associated with CVD hospital admissions. The consideration of such interaction will help in policy making and public health interventions dealing with climate change-related health risks.

The association between ambient temperature and sperm quality in Wuhan, China

BACKGROUND

Few epidemiological investigations have focused on the influence of environmental temperature on human sperm quality. Here, we evaluated the potential association between ambient temperature and human sperm quality in Wuhan, China, and examined the interactive effect of particulate matter (PM_2.5) and temperature.

METHODS

1780 males who had been living in Wuhan for no less than three months and received semen analysis at the Department of Reproductive Medicine in Renmin Hospital of Wuhan University between April 8, 2013 and June 30, 2015 were recruited. Daily mean meteorological data and air pollution data (PM_2.5, O₃ and NO₂) in Wuhan between 2013 and 2015 were collected. A generalized linear model was used to explore the associations between ambient temperature and sperm quality (including sperm concentration, percentage of normal sperm morphology, and progressive motility) at 0-9, 10-14, 15-69, 70-90, and 0-90 days before semen examination, and the interaction between temperature and PM_2.5.

RESULTS

The associations between ambient temperature and sperm quality were an inverted U-shape at five exposure windows, except for a lag of 0-9 days for sperm concentration. A 1 °C increase in ambient temperature above the thresholds was associated with a 2.038 (1.292 ~ 2.783), 1.814 (1.217 ~ 2.411), 1.458 (1.138 ~ 1.777), 0.934(0.617 ~ 1.251) and 1.604 (1.258 ~ 1.951) decrease in the percentage of normal sperm morphology at lag 0-9, lag 10-14, lag 15-69, lag 70-90, and lag 0-90 days, respectively. The interaction p-values of PM_2.5 and temperature were mostly less than 0.05 at five exposure windows. When ambient temperature exposure levels were above the thresholds, a 0.979 (0.659-1.299) and 3.559 (0.251 ~ 6.867) decrease in percentage of normal sperm morphology per 1 °C increase in temperature at lag 0-90 days was observed in the PM_2.5 ≤ P₅₀ group and PM_2.5 > P₅₀ group, respectively.

CONCLUSIONS

Our results indicate that exposure to ambient temperature has a threshold effect on sperm quality, and PM_2.5 enhances the effect of temperature on sperm quality when temperatures are above the threshold.

Modification Effects of Temperature on the Ozone-Mortality Relationship: A Nationwide Multicounty Study in China

Both ozone exposure and extreme temperatures are found to be significantly associated with mortality; however, inconsistent results have been obtained on the modification effects of temperature on the ozone-mortality association. In the present study, we conducted a nationwide time-series analysis in 128 counties from 2013-2018 to examine whether temperature modifies the association between short-term ozone exposure with nonaccidental and cause-specific mortality in China. First, we analyzed the effects of ozone exposure on mortality at different temperature levels. Then, we calculated the pooled effects through a meta-analysis across China. We found that high-temperature conditions (>75th percentile in each county) significantly enhanced the effects of ozone on nonaccidental, cardiovascular, and respiratory mortality, with increases of 0.44% (95% confidence interval (CI): 0.36 and 0.51%), 0.42% (95% CI: 0.32 and 0.51%) and 0.50% (95% CI: 0.31 and 0.68%), respectively, for a 10 μg/m³ increase in ozone at high temperatures. Stronger effects on nonaccidental and cardiovascular mortality were observed at high temperatures among elderly individuals aged 65 years and older compared with the younger people. Our findings provide evidence that health damage because of ozone may be influenced by the impacts of increasing temperatures, which point to the importance of mitigating ozone exposure in China under the context of climate change to further reduce the public health burden.

Particulate Matter and Its Impact on Mortality among Elderly Residents of Seoul, South Korea

Climate change, air pollution, and the rapidly aging population are important public health challenges. An understanding of air pollution impacts is imperative for preventing air-pollution-related deaths and illnesses, particularly in vulnerable subgroups such as the increasing population of older adults. To assess the effects of short-term air-pollution exposure on the elderly, we conducted a time-series analysis (1996–2015) of the associations between particulate matter with an aerodynamic diameter of <10 μm (PM10) and deaths among elderly residents of Seoul, South Korea, which has a rapidly aging population. We also investigated the synergistic effects of temperature and the lag structures of the effects by sex, cause of death, and season. A 10 μg/m3 rise in the 4-day moving average concentration of PM10 was associated with 0.31% (95% confidence interval (CI): 0.18% to 0.44%), 0.32% (95% CI: 0.09% to 0.55%), and 0.22% (95% CI: –0.23% to 0.66%) increases in non-accidental, cardiovascular, and respiratory mortalities, respectively. We found a significant and strong synergistic effect of PM10 concentration and ambient temperature on mortality in elderly people. PM10 posed an increased risk of non-accidental or cardiovascular mortality with increasing temperature, whereas the associated risk of respiratory death was highest on very cold days. The shape and length of the lag structure varied with the cause of death, sex, and season. Results indicate that elderly people exposed to PM10 are at increased risk of premature death. In the near future, these risks are likely to increase in step with the temperature rise associated with climate change and the continued population aging. Stronger emission controls will be needed to minimize the increased health risks associated with air pollution, especially in regions with high populations of elderly individuals.

Hourly associations between ambient air pollution and emergency ambulance calls in one central Chinese city: Implications for hourly air quality standards

BACKGROUND

Most studies on the short-term health effects of air pollution have been conducted on a daily time scale, while hourly associations remain unclear.

METHODS

We collected the hourly data of emergency ambulance calls (EACs), ambient air pollution, and meteorological variables from 2014 to 2016 in Luoyang, a central Chinese city in Henan Province. We used a generalized additive model to estimate the hourly effects of ambient air pollutants (PM_2.5, PM₁₀, SO₂, and NO₂) on EACs for all natural causes and cardiovascular and respiratory morbidity, with adjustment for potential confounding factors. We further examined the effect modification by temperature, relative humidity, wind speed, and atmospheric pressure using stratified analyses.

RESULTS

In the single-pollutant models, PM_2.5, PM₁₀, SO₂, and NO₂ were associated with an immediate increase in all-cause morbidity at 0, 0, 12, 10 h, separately, after exposure to these pollutants (excess risks: 0.19% (95% confidence interval (CI): 0.03%, 0.35%), 0.13% (95% CI: 0.02%, 0.24%), 0.28% (95% CI: 0.01%, 0.54%) and 0.52% (95% CI: 0.06%, 0.99%), respectively). These effects remained generally stable in two-pollutant models. SO₂ and NO₂ were significantly associated with an immediate increase in risk of cardiovascular morbidity, but the effects on respiratory morbidity were relatively more delayed. The stratified analyses suggested that temperature could modify the association between PM_2.5 and EACs, humidity and atmospheric pressure could modify the association between SO₂ and EACs.

CONCLUSIONS

Our study provides new evidence that higher concentrations of PM_2.5, PM₁₀, SO₂, and NO₂ may have transiently acute effects on all-cause morbidity and subacute effects on respiratory morbidity. SO₂ and NO₂ may also have immediate effects on cardiovascular morbidity. Findings of this study have important implications for the formation of hourly air quality standards.

Synergic effect between high temperature and air pollution on mortality in Northeast Asia

High temperature and air pollutants have been reported as potential risk factors of mortality. Previous studies investigated interaction between the two variables; however, the excess death risk due to the synergic effect (i.e. interaction on the additive scale) between the two variables has not been investigated adequately on a multi-country scale. This study aimed to assess the excess death risk due to the synergism between high temperature and air pollution on mortality using a multicity time-series analysis. We collected time-series data on mortality, weather variables, and four air pollutants (PM₁₀, O₃, NO₂, and CO) for 16 metropolitan cities of three countries (Japan, Korea, and Taiwan) in Northeast Asia (1979-2015). Quasi-Poisson time-series regression and meta-analysis were used to estimate the additive interaction between high temperature and air pollution. The additive interaction was measured by relative excess risk due to interaction (RERI) index. We calculated RERI with relative risks (RR) of the 99th/10th, 90th/90th, and 99th/90th percentiles of temperature/air pollution metrics, where risk at the 90th/10th percentiles of temperature/air pollution metrics was the reference category. This study showed that there may exist positive and significant excess death risks due to the synergism between high temperature and air pollution in the total population for all pollutants (95% lower confidence intervals of all RERIs>0 or near 0). In final, we measured quantitatively the excess death risks due to synergic effect between high temperature and air pollution, and the synergism should be considered in public health interventions and a composite warning system.

Short-term exposure to ambient air pollution and daily atherosclerotic heart disease mortality in a cool climate

The associations between exposure to short-term ambient air pollution and daily atherosclerotic heart disease (ASHD) mortality in cool climate have not been established. We performed a time-series analysis in Shenyang, the largest city of Northeastern China. We identified 7659 ASHD deaths and obtained deaths, ambient air pollution levels, and meteorological data for Shenyang during 2014-2017. The impact of ambient air pollution on daily ASHD deaths was analyzed using generalized additive models (GAMs). Cumulative lag effects were investigated using distributed lag non-linear models (DLNM). We found ASHD deaths significantly increased during days with higher air pollution. Particulate matter with diameter < 2.5 μm (PM_2.5), PM₁₀, and sulfur dioxide (SO₂) were positively associated with ASHD deaths among the total population. Both single- and multi-pollutants models indicated that PM_2.5, PM₁₀, and sulfur dioxide (SO₂) were positively associated with the deaths of women with AHSD, whereas only SO₂ was significant in men. This suggests significant gender-based differences in the fatal effects of ambient air pollution. Up to 28 days of single-day lag effects were observed for PM_2.5 and PM₁₀ in women. The cumulative lag effects of PM_2.5 and PM₁₀ showed increasing trends in both men and women; however, exposure to higher pollutant concentrations did not necessarily translate to greater risks. The ERRs differences between women and men were larger in cold days than in hot days, suggesting that lower temperature may exacerbate the adverse effects of air pollution on vulnerable women.

Interactions between ambient air pollutants and temperature on emergency department visits: Analysis of varying-coefficient model in Guangzhou, China

BACKGROUND

At present, there are few studies on the effect of short-term interactions between ambient air pollutants and temperature on cause-specific emergency department visits in China. This study aimed to explore their short-term interactions on cause-specific emergency department visits using data collected from a total of 65 public hospitals in Guangzhou city, south China.

MATERIAL AND METHODS

We included a total of 226,443 emergency department visits which were diagnosed as neurological, respiratory and circulatory disease in Guangzhou from January 1, 2014 to December 31, 2017. Average daily concentrations of air pollutants including carbon monoxide (CO), particulate matter having a median diameter of 2.5 μm or less (PM_2.5), sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃) were collected from the Guangzhou Environmental Protection Bureau. We employed quasi-Poisson varying coefficient regression models to assess the interaction effects between air pollutants and daily temperature levels (DTLs) on emergency department visits for neurological, respiratory and circulatory diseases, respectively.

RESULTS

Average number of emergency department visits for neurological, respiratory and circulatory diseases were 92, 26 and 38, respectively. After controlling for other pollutants, meteorological factors and other time-varying confounders, we found the interactions between NO₂ and the 1st DTL (3.4-17.1 °C), NO₂ and the 2nd DTL (17.1-23.5 °C) for neurological emergency department visits were statistically significant, displaying a nonlinear relationship. Additionally, we found that the interactions between SO₂ and the 4th DTL (27.4-31.1 °C) also had a significantly adverse effect on respiratory emergency department visits.

CONCLUSIONS

Our findings provide novel evidence on SO₂-by-temperature interactions, and NO₂-by-temperature interactions for emergency department visits of cause-specific diseases.

Particulate Matter Mortality Rates and Their Modification by Spatial Synoptic Classification

Air pollution levels are highly correlated with temperature or humidity, so we investigated the relationship between PM₁₀ and the spatial synoptic classification (SSC) scheme on daily mortality, according to age group and season. Daily death data for 2000-2014 from Seoul, Korea, were acquired, and time-series analysis was applied with respect to season and to each of seven distinct SSC types: dry moderate (DM); dry polar (DP); dry tropical (DT); moist moderate (MM); moist polar (MP); moist tropical (MT); and transition (T). Modification effects were estimated for daily, non-accidental, cardiovascular, and respiratory mortality between PM₁₀ and SSC types. The following SSC-type-specific increased mortalities were observed, by cause of death: non-accidental mortality: DT (1.86%) and MT (1.86%); cardiovascular mortality: DT (2.83%) and MM (3.00%); respiratory mortality: MT (3.78%). Based on simplified weather types, increased PM₁₀ effects in non-accidental mortality rates were observed in dry (1.54%) and moist (2.32%) conditions among those aged 40-59 years and were detected regardless of conditions in other age groups: 60-74 (1.11%), 75-84 (1.55%), and 85+ (1.75%). The effects of particulate air pollution, by SSC, suggest the applicability of SSC to the comparison and understanding of acute effects of daily mortality based on weather type.

Particulate air pollution on cardiovascular mortality in the tropics: impact on the elderly

BACKGROUND

Air pollution has a significant health impact. Most data originate from temperate regions. We aim to study the health impact of air pollution, particularly among the elderly, in a tropical region.

METHODS

A daily time-series analysis was performed to estimate excess risk (ER) of various air pollutants on daily death counts amongst the general population in Singapore from 2001 to 2013. Air pollutants included particulate matters smaller than 10 μm, and 2.5 μm (PM₁₀, PM_2.5), carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃) and sulphur dioxide (SO₂). The studied outcomes were non-accidental and cardiovascular mortality. Single-day lag and distributed lag models were studied and adjusted for confounders.

RESULTS

In single-day lag models, a 10 μg/m³ increase in particulate matter was associated with significant increases in non-accidental (PM₁₀ ER: 0.627%; 95% confidence interval (CI): 0.260-0.995% and PM_2.5 ER: 0.660%; 95% CI: 0.204-1.118%) and cardiovascular mortality (PM₁₀ ER: 0.897; 95% CI: 0.283-1.516 and PM_2.5 ER: 0.883%; 95% CI: 0.121-1.621%). This was significant in the elderly ≥ 65 years but not in those < 65 years and were seen in the acute phase of lag 0-5 days. Effects by other pollutants were minimal. For cardiovascular mortality, the effects turned protective at a cumulative lag of 30 days in the elderly and could due to "harvesting".

CONCLUSIONS

These first contemporary population-based data from an equatorial country with tropical climate show that exposure to particulate air pollution was significantly associated with non-accidental mortality and cardiovascular mortality, especially in the elderly.

Impact of temperature and air pollution on cardiovascular disease and death in Iran: A 15-year follow-up of Tehran Lipid and Glucose Study

In this, the first study to be conducted in the Middle East and North Africa (MENA) on the subject, we examined the impact of temperature and air pollution on cardiovascular disease (CVD) and all-cause mortality. The Tehran Lipid and Glucose Study followed 9731 participants, aged ≥30years (men=4409), during the period 1999-2014, reporting 1350 CVDs (men=796) and 725 deaths (men=447). Air pollution level was measured using the air quality index (AQI). Data were analyzed using the distributed lag nonlinear model, with 30°C temperature and AQI=50 minimum risk values, as the relative risks' (RR) reference values. Although for the whole sample, no significant effect of air pollution was observed on CVD, for the under 60year olds, two significant peaks occurred in AQI=180 at lags 2 and 6days (RR=1.94, 95% CI: 1.02-3.67 and 2.06, 95% CI: 1.09-3.88, respectively). Temperature had no significant effect on CVD, yet the closest case to significance happened at 36°C and lag 5days (RR=1.43, 95% CI: 0.97-2.11), for ages ≥60y. The largest significant effects of air pollution on death, occurred in AQI=180 and lag 1day (RR=2.40, 95% CI: 1.0.-5.59 and 3.29, 95% CI: 1.15-9.36, for the whole sample and the <60year olds, respectively). Interestingly, for those aged over 60years, the peak belonged to AQI=180 and lag 7days (RR=2.16, 95% CI: 1.11-4.19). Regarding the effect of temperature on death among the whole sample, the highest risk was for 6°C and lag 0 (RR=3.91, 95% CI: 1.12-13.61). For the ≥60year olds, it occurred in 9⁺ and lag 0 (RR=6.81, 95% CI: 1.69-27.44), though notably, the peak went to -3°C and lag 3 (RR=5.69, 95% CI: 1.12-28.87), for those aged <60years. Overall, the effect of low temperature on death had the highest risk, for the over 60-year-olds, without any lag. Moreover, the <60-year-olds were the most vulnerable group to air pollution with a one day lag, in terms of mortality risk.

The association between short and long-term exposure to PM2.5 and temperature and hospital admissions in New England and the synergistic effect of the short-term exposures

BACKGROUND

Particulate matter < 2.5 μm in diameter (PM2.5) and heat are strong predictors of morbidity, yet few studies have examined the effects of long-term exposures on non-fatal events, or assessed the short and long-term effect on health simultaneously.

OBJECTIVE

We jointly investigated the association of short and long-term exposures to PM2.5 and temperature with hospital admissions, and explored the modification of the associations with the short-term exposures by one another and by temperature variability.

METHODS

Daily ZIP code counts of respiratory, cardiac and stroke admissions of adults ≥65 (N = 2,015,660) were constructed across New-England (2001-2011). Daily PM2.5 and temperature exposure estimates were obtained from satellite-based spatio-temporally resolved models. For each admission cause, a Poisson regression was fit on short and long-term exposures, with a random intercept for ZIP code. Modifications of the short-term effects were tested by adding interaction terms with temperature, PM2.5 and temperature variability.

RESULTS

Associations between short and long-term exposures were observed for all of the outcomes, with stronger effects of long-term exposures to PM2.5. For respiratory admissions, the short-term PM2.5 effect (percent increase per IQR) was larger on warmer days (1.12% versus -0.53%) and in months of higher temperature variability (1.63% versus -0.45%). The short-term temperature effect was higher in months of higher temperature variability as well. For cardiac admissions, the PM2.5 effect was larger on colder days (0.56% versus -0.30%) and in months of higher temperature variability (0.99% versus -0.56%).

CONCLUSIONS

We observed synergistic effects of short-term exposures to PM2.5, temperature and temperature variability. Long-term exposures to PM2.5 were associated with larger effects compared to short-term exposures.

Impact of air pollution on cause-specific mortality in Korea: Results from Bayesian Model Averaging and Principle Component Regression approaches

Health effects related to air pollution are a major global concern. Related studies based on reliable exposure assessment methods would potentially enable policy makers to propose appropriate environmental management policies. In this study, integrated Bayesian Model Averaging (BMA) and Principle Component Regression (PCR) were adopted to assess the severity of air pollution impacts on mortality related to circulatory, respiratory and skin diseases in 25 districts of Seoul, South Korea for the years 2005-2015. These methods were consistent in determining the best regression models and most important pollutants related to mortality in those highly susceptible to poor air quality. Specifically, the results demonstrated that pneumonia was highly associated with air pollution, with a large determination coefficient (BMA: 0.46, PCR: 0.51) and high model's posterior probability (0.47). The most reliable prediction model for pneumonia was indicated by the lowest Bayesian Information Criterion. Among the pollutants, particulate matter with an aerodynamic diameter of 10 μm or less (PM₁₀) was associated with serious health risks on evaluation, with the highest posterior inclusion probabilities (range, 80.20 to 100.00%) and significantly positive correlation coefficients (range, 0.14 to 0.34, p < 0.05). In addition, excessive PM₁₀ concentration (approximately 2.54 times the threshold) and a continuous increase in mortality due to respiratory diseases (approximately 1.50-fold in 10 years) were also exhibited. Overall, the results of this study suggest that currently, socio-environmental policies and international collaboration to mitigate health effects of air pollution is necessary in Seoul, Korea. Moreover, consideration of uncertainty of the regression model, which was verified in this research, will facilitate further application of this approach and enable optimal prediction of interactions between human and environmental factors.

Two-way effect modifications of air pollution and air temperature on total natural and cardiovascular mortality in eight European urban areas

BACKGROUND

Although epidemiological studies have reported associations between mortality and both ambient air pollution and air temperature, it remains uncertain whether the mortality effects of air pollution are modified by temperature and vice versa. Moreover, little is known on the interactions between ultrafine particles (diameter ≤ 100 nm, UFP) and temperature.

OBJECTIVE

We investigated whether the short-term associations of particle number concentration (PNC in the ultrafine range (≤100 nm) or total PNC ≤ 3000 nm, as a proxy for UFP), particulate matter ≤ 2.5 μm (PM_2.5) and ≤ 10 μm (PM₁₀), and ozone with daily total natural and cardiovascular mortality were modified by air temperature and whether air pollution levels affected the temperature-mortality associations in eight European urban areas during 1999-2013.

METHODS

We first analyzed air temperature-stratified associations between air pollution and total natural (nonaccidental) and cardiovascular mortality as well as air pollution-stratified temperature-mortality associations using city-specific over-dispersed Poisson additive models with a distributed lag nonlinear temperature term in each city. All models were adjusted for long-term and seasonal trend, day of the week, influenza epidemics, and population dynamics due to summer vacation and holidays. City-specific effect estimates were then pooled using random-effects meta-analysis.

RESULTS

Pooled associations between air pollutants and total and cardiovascular mortality were overall positive and generally stronger at high relatively compared to low air temperatures. For example, on days with high air temperatures (>75th percentile), an increase of 10,000 particles/cm³ in PNC corresponded to a 2.51% (95% CI: 0.39%, 4.67%) increase in cardiovascular mortality, which was significantly higher than that on days with low air temperatures (<25th percentile) [-0.18% (95% CI: -0.97%, 0.62%)]. On days with high air pollution (>50th percentile), both heat- and cold-related mortality risks increased.

CONCLUSION

Our findings showed that high temperature could modify the effects of air pollution on daily mortality and high air pollution might enhance the air temperature effects.

Higher health effects of ambient particles during the warm season: The role of infiltration factors

A large number of studies have shown much higher health effects of particulate matter (PM) during the warm compared to the cold season. In this paper we present the results of an experimental study carried out in an unoccupied test apartment with the aim of understanding the reasons behind the seasonal variations of the health effects due to ambient PM_2.5 exposure. Measurements included indoor and outdoor PM_2.5 mass and chemical composition as well as particle size distribution of ultrafine particles. Monitoring campaigns were carried out during summer and winter following a ventilation protocol developed to replicate typical occupant behaviour according to a questionnaire-based survey. Our findings showed that seasonal variation of the relationship between ambient and indoor mass concentrations cannot entirely explain the apparent difference in PM toxicity between seasons and size distribution and chemical composition of particles were identified as other possible causes of changes in the apparent PM toxicity. A marked decrease of ultrafine particles (<100 nm) passing from outdoors to indoors was observed during winter; this resulted in higher indoor exposure to nanoparticles (<50 nm) during summer. With regards to the chemical composition, a pooled analysis showed infiltration factors of chemical species similar to that obtained for PM_2.5 mass with values increasing from 0.73 during winter to 0.90 during summer and few deviations from the pooled estimates. In particular, significantly lower infiltration factors and sink effect were found for nitrates and ammonium during winter. In addition, a marked increase in the contribution of indoor and outdoor sulfates to the total mass was observed during summer.

The effects of interaction between particulate matter and temperature on mortality in Beijing, China

BACKGROUND

the effects of interaction between temperature and inhalable particulate matter (aerodynamic diameter < 10 μm, PM₁₀) on mortality have been examined in some previous studies, but the results were inconsistent. This study aims to explore whether the effects of PM₁₀ on daily non-accidental, cardiovascular and respiratory mortality were modified by temperature levels in Beijing from 2006 to 2009.

METHODS

we applied a bivariate response surface model and temperature-stratified model based on time-series Poisson generalized additive models (GAMs) to examine the interactive effects in single- and two-pollutant models. The modification of age and gender was examined in subgroup analyses.

RESULTS

the median of temperature (15.9 °C) and visualized turning point (20 °C) were chosen as cut-offs to define the temperature strata as two levels (low and high). Results showed that the effect estimates of PM₁₀ were stronger at the high temperature level for non-accidental, cardiovascular and respiratory mortality than at the low temperature level. When controlling the moving average lag of temperature for 14 days, the effect estimates per 10 μg m^-3 increase in PM₁₀ for non-accidental, cardiovascular and respiratory mortality increased 0.14% (95% CI: 0.05, 0.22), 0.12% (95% CI: 0.02, 0.23) and 0.14% (95% CI: -0.06, 0.34) when the temperature was low and 0.24% (95% CI: 0.12, 0.35), 0.17% (95% CI: 0.01, 0.34) and 0.45% (95% CI: 0.13, 0.78) at the high temperature level, respectively. In the two-pollutant model, the effects of PM₁₀ were attenuated at both high and low temperatures at all lags after adjusting SO₂ and NO₂. The PM₁₀ effects were stronger at the high temperature level for females and elderly people (≥65 years old).

CONCLUSION

the findings suggest that daily mortality attributed to PM₁₀ might be modified by temperature. The interaction between air pollution and global climate change has potential strategy and policy implications.

Association between air pollution and cardiovascular mortality in China: a systematic review and meta-analysis

Air pollutant levels in many Chinese cities remained significantly higher than the upper limits stated in World Health Organization guidelines. In light of limited evidence in China, we conducted a meta-analysis summarizing the association between acute exposure of air pollution and cardiovascular mortality. We searched PubMed, and CNKI databases etc. for literature published in English or Chinese up to January 2017. Outcomes were pooled and compared using random-effects model. Excess risks (ERs) per 10 μg/m³ increase in PM_2.5, PM₁₀, NO₂, SO₂ and O₃ were evaluated. Subgroup analysis was conducted according to lag patterns (lags 0, 1, 2, 0–1, 0–2 days), gender (male vs. female), temperature (cool vs. warm) and age (< 65 vs. ≥ 65). Study bias was detected using Begg’s and Egger’s test. Of 299 articles identified, 30 met inclusion criteria. Each 10 μg/m³ increase in the concentration was associated with a higher incidence of cardiovascular mortality for PM_2.5 (0.68%, 95% CI: 0.39–0.97%), PM₁₀ (0.39%, 95% CI: 0.26–0.53%), NO₂ (1.12%, 95% CI: 0.76–1.48%), SO₂ (0.75%, 95% CI: 0.42–1.09%), and O₃ (0.62%, 95% CI: 0.33–0.92%), respectively. Air pollution conferred greater adverse impacts on cardiovascular mortality for longer duration of exposures. Strongest associations were seen for lag 0–1 day of exposure among all pollutants. Female, lower temperature, and age > 65 years were associated with greater risks of cardiovascular mortality for all pollutants. Higher concentrations of air pollutants correlated with a greater short-term increase in cardiovascular mortality. Further high-quality studies in China are urgently warranted to determine the susceptible population, which would offer reference for policy-making to minimize adverse health effects.

Estimation of abnormal temperature effects on elderly mortality in South Korea using the temperature deviation index

Recent studies have revealed that the effect of temperature on mortality has changed over time. One of the major contributors to the changes is adaptation. We aimed to understand the relationship between elderly mortality and temperature anomaly using the temperature deviation index (TDI), which considers exposure history. Summertime (May to September) mortality data from 1996 to 2014 and meteorological data from 1971 to 2014 were obtained for 16 regions covering South Korea. The TDI was defined as the target day's temperature abnormality compared to previous 25 years' apparent temperature (AT). The relationship between the TDI and elderly mortality for each region was examined by generalized linear modeling with Poisson distribution. Pooled estimates were computed to yield a national effect estimate. Stratified analyses were performed using the percentiles of AT and TDI. Most regions showed positive linear associations, and the associations ranged from 0.4 to 4.3% increase per unit increase of the TDI. In the pooled analyses, a unit increase of the TDI was associated with a 1.4% increase (95% confidence interval [CI] 0.93-1.87) in elderly mortality. In the stratified analysis, the relationship between the TDI and elderly mortality was significant at or above the 75th percentile of AT (1.32% increase; 95% CI 0.47-2.22). We suggest a positive association between the TDI and elderly mortality in South Korea. The association observed particularly in the highest percentile of AT in the stratified analysis suggests independent effects of temperature anomaly in addition to those of absolute AT.

Acute effects of ambient temperature and particulate air pollution on fractional exhaled nitric oxide: A panel study among diabetic patients in Shanghai, China

Background

Epidemiological studies have shown the associations of ambient temperature and particulate matter (PM) air pollution with respiratory morbidity and mortality. However, the underlying mechanisms have not been well characterized. The aim of this study is to investigate the associations of temperature and fine and coarse PM with fractional exhaled nitric oxide (FeNO), a well-established biomarker of respiratory inflammation.

Methods

We conducted a longitudinal panel study involving six repeated FeNO tests among 33 type 2 diabetes mellitus patients from April to June 2013 in Shanghai, China. Hourly temperature and PM concentrations were obtained from a nearby fixed-site monitoring station. We then explored the associations between temperature, PM, and FeNO using linear mixed-effect models incorporated with distributed lag nonlinear models for the lagged and nonlinear associations. The interactions between temperature and PM were evaluated using stratification analyses.

Results

We found that both low and high temperature, as well as increased fine and coarse PM, were significantly associated with FeNO. The cumulative relative risk of FeNO was 1.75% (95% confidence interval [CI], 1.04–2.94) comparing 15 °C to the referent temperature (24 °C) over lags 0–9 days. A 10 μg/m³ increase in fine and coarse PM concentrations were associated with 1.18% (95% CI, 0.18–2.20) and 1.85% (95% CI, 0.62–3.09) FeNO in lag 0–1 days, respectively. PM had stronger effects on cool days than on warm days.

Conclusions

This study suggested low ambient temperature, fine PM, and coarse PM might elevate the levels of respiratory inflammation. Our findings may help understand the epidemiological evidence linking temperature, particulate air pollution, and respiratory health.

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Both low and high temperatures were significantly associated with FeNO.

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The increases of fine and coarse PM concentrations were associated with FeNO.

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Both fine and coarse PM had stronger effects in cool days.

Does temperature modify the effect of PM10 on mortality? A systematic review and meta-analysis

Large and growing literature has explored whether temperature modified the effect of particular matter (PM) on mortality, but results of the modification effect are inconsistent. In this study, we reviewed information from 29 studies to get the qualitative evidence of the modification effects of temperature on PM to mortality, and the data from 16 of the 29 studies were extracted to conduct a meta-analysis. Temperatures were grouped into three level: "low", "middle" and "high" according to the original studies. The random effect model was used in the meta-analysis with the relative risk (RR) as the measure indicator. The RRs (95% confidence intervals, CIs) for non-accidental death, cardiovascular death and respiratory death per 10 μg/m³ increase in PM₁₀ were 1.004 (1.003, 1.006), 1.005 (1.003,1.007), and 1.005 (1.000,1.010) in the low temperature level, 1.005 (1.004,1.006), 1.005 (1.004,1.007), and 1.008 (1.006, 1.010) in the middle temperature level, and 1.012 (1.010, 1.015), 1.016 (1.010, 1.022) and 1.019 (1.010,1.028) in the high temperature level, respectively. In conclusion, moderate evidence exists that temperature modifies the effect of PM₁₀ on mortality. The effect of PM₁₀ on respiratory death was the greatest, while the effect on non-accidental death was the smallest in the same temperature level. In addition, the effects of PM₁₀ on all the three kinds of mortality were the biggest in the high-temperature level, and the smallest in the low-temperature level.

Associations between Environmental Quality and Mortality in the Contiguous United States, 2000-2005

BACKGROUND

Assessing cumulative effects of the multiple environmental factors influencing mortality remains a challenging task.

OBJECTIVES

This study aimed to examine the associations between cumulative environmental quality and all-cause and leading cause-specific (heart disease, cancer, and stroke) mortality rates.

METHODS

We used the overall Environmental Quality Index (EQI) and its five domain indices (air, water, land, built, and sociodemographic) to represent environmental exposure. Associations between the EQI and mortality rates (CDC WONDER) for counties in the contiguous United States (n = 3,109) were investigated using multiple linear regression models and random intercept and random slope hierarchical models. Urbanicity, climate, and a combination of the two were used to explore the spatial patterns in the associations.

RESULTS

We found 1 standard deviation increase in the overall EQI (worse environment) was associated with a mean 3.22% (95% CI: 2.80%, 3.64%) increase in all-cause mortality, a 0.54% (95% CI: -0.17%, 1.25%) increase in heart disease mortality, a 2.71% (95% CI: 2.21%, 3.22%) increase in cancer mortality, and a 2.25% (95% CI: 1.11%, 3.39%) increase in stroke mortality. Among the environmental domains, the associations ranged from -1.27% (95% CI: -1.70%, -0.84%) to 3.37% (95% CI: 2.90%, 3.84%) for all-cause mortality, -2.62% (95% CI: -3.52%, -1.73%) to 4.50% (95% CI: 3.73%, 5.27%) for heart disease mortality, -0.88% (95% CI: -2.12%, 0.36%) to 3.72% (95% CI: 2.38%, 5.06%) for stroke mortality, and -0.68% (95% CI: -1.19%, -0.18%) to 3.01% (95% CI: 2.46%, 3.56%) for cancer mortality. Air had the largest associations with all-cause, heart disease, and cancer mortality, whereas the sociodemographic index had the largest association with stroke mortality. Across the urbanicity gradient, no consistent trend was found. Across climate regions, the associations ranged from 2.29% (95% CI: 1.87%, 2.72%) to 5.30% (95% CI: 4.30%, 6.30%) for overall EQI, and larger associations were generally found in dry areas for both overall EQI and domain indices.

CONCLUSIONS

These results suggest that poor environmental quality, particularly poor air quality, was associated with increased mortality and that associations vary by urbanicity and climate region. Citation: Jian Y, Messer LC, Jagai JS, Rappazzo KM, Gray CL, Grabich SC, Lobdell DT. 2017. Associations between environmental quality and mortality in the contiguous United States, 2000-2005. Environ Health Perspect 125:355-362; http://dx.doi.org/10.1289/EHP119.

Spatial variation of air quality index and urban driving factors linkages: evidence from Chinese cities

Daily air quality index (AQI) of 161 Chinese cities obtained from the Ministry of Environmental Protection of China in 2015 is conducted. In this study, to better explore spatial distribution and regional characteristic of AQI, global and local spatial autocorrelation is utilized. Pearson's correlation is introduced to determine the influence of single urban indicator on AQI value. Meanwhile, multiple linear stepwise regression is chosen to estimate quantitatively the most influential urban indicators on AQI. The spatial autocorrelation analysis indicates that the AQI value of Chinese 161 cities shows a spatial dependency. Higher AQI is mainly located in north and northwest regions, whereas low AQI is concentrated in the south and the Qinghai-Tibet regions. The low AQI and high AQI values in China both exhibit relative immobility through seasonal variation. The influence degree of three adverse urban driving factors on AQI value is ranked from high to low: coal consumption of manufacturing > building area > coal consumption of the power industry. It is worth noting that the risk of exposed population to poor quality is greater in the northern region than in other regions. The results of the study provide a reference for the formulation of urban policy and improvement of air quality in China.

Seasonal analysis of the short-term effects of air pollution on daily mortality in Northeast Asia

The constituents and concentrations of pollutants, individual exposures, and biologic responses to air pollution may vary by season and meteorological conditions. However, evidence regarding seasonality of the acute effects of air pollution on mortality is limited and inconsistent. Herein, we examined seasonal patterns in the short-term associations of particulate matter (PM) smaller than 10μm (PM₁₀) with daily mortality in 29 cities of three northeast Asian countries. Stratified time-series models were used to determine whether season altered the effect of PM₁₀ on mortality. This effect was first quantified within each season and at each location using a time-series model, after which city-specific estimates were pooled using a hierarchical Bayesian model. In all data sets, 3,675,348 non-accidental deaths were registered from 1993 to 2009. In Japan, a 10μg/m³ increase in PM₁₀ was significantly associated with increases in non-accidental mortality of 0.44% (95% confidence interval [CI]: 0.03%, 0.8%) in spring and 0.42% (0.02%, 0.82%) in fall. In South Korea, a 10μg/m³ increase in PM₁₀ was significantly associated with increases in non-accidental mortality of 0.51% (0.01%, 1.01%) in summer and 0.45% (0.03%, 0.87%) in fall, in cardiovascular disease mortality of 0.96% (0.29%, 1.63%) in fall, and in respiratory disease mortality of 1.57% (0.40%, 2.75%) in fall. In China, a 10μg/m³ increase in PM₁₀ was associated with increases in non-accidental mortality of 0.33% (0.01%, 0.66%) in summer and 0.41% (0.09%, 0.73%) in winter, in cardiovascular disease mortality of 0.41% (0.08%, 0.74%) in spring and 0.33% (0.02%, 0.64%) in winter, and in respiratory diseases mortality of 0.78% (0.27%, 1.30%) in winter. Our analyses suggest that the acute effect of particulate air pollution could vary seasonally and geographically.