Long-Term Exposure to Source-Specific Fine Particles and Mortality─A Pooled Analysis of 14 European Cohorts within the ELAPSE Project

Evaluating the health impact of air pollution control strategies and synergies among PM2.5 and O3 pollution in Beijing-Tianjin-Hebei region, China

Since 2013, China has implemented a series of strict Air Pollution Control Strategies (APCS) to mitigate environmental and health risks associated with ambient fine particulate matter (PM2.5). However, while APCS sets clear targets for PM2.5 concentration, it lacks quantitative control over O3 levels. Most existing studies have focused on nation-wide health assessments. Therefore, by conducting a coupled framework using health assessment and decomposition method, the spatiotemporal variation in deaths attributable to PM2.5 pollution, as well as the role of APCS and the synergies between PM2.5 and O3 on PM2.5 concentration and health impacts in the Beijing-Tianjin-Hebei (BTH) region have been explored. The result showed that: (1) PM2.5 concentration in the BTH region decreased by 68.2%, with a reduction of 45,833 (95% Confidence Interval [CI]: 33,808, 50,069) deaths over the period. However, both concentrations and mortality remained high, indicating a need for faster reductions. (2) End-of-pipe control contributed the most to reducing PM2.5 concentrations and deaths, though the gaps between source control and end-of-pipe control is narrowing. (3) The synergistic effects of O3 and PM2.5 in reducing concentration and mortality have increased, becoming a significant driver of PM2.5-related health impacts. Our study emphasizes the future importance of implementing refined, diverse emission reduction measures and coordinating efforts to reduce both O3 and PM2.5 emissions, which are crucial for achieving the Sustainable Development Goals (SDGs) and advancing the "Beautiful China" and "Healthy China" initiatives.

Implications of spatial and seasonal air pollution patterns, socioeconomic disparities, and 15-minute communities for achieving WHO air quality guidelines

Achieving WHO air pollution guidelines is critical to reduce the health burden of air pollution, which disproportionately affects socioeconomically disadvantaged populations and varies by sector, spatial distribution, and seasonal trends. This study explores the implications of sectorial and spatial-seasonal air pollution patterns, socio-economic disparities, and 15-minute communities to achieve (2021) WHO air quality guidelines for PM2.5 and NO2. The study analyses spatial-temporal patterns of air pollution in Belgium. Seasonal air pollution exposure is assessed through summer-to-winter ratios, stratified by land cover, urbanisation, and proximity to roads, and linked to socio-economic disparities using LOESS regression. A case study evaluates the mitigation potential of 15-minute communities for traffic-related air pollution, leveraging the Mobiscore tool to explore the relationship between accessibility and car ownership, a proxy for traffic-related emissions. NO2 and PM2.5 show marked seasonal and spatial variations, with higher concentration ratios in summer near busy roads and urban centres, especially for NO2. In general the NO2 spatial-seasonal pattern is more heterogenous compared to the PM2.5 pattern. Winter pollution exposure significantly hampers meeting WHO health targets, although summer levels of NO2 remain high around major traffic routes. The observed disparities in exposure to NO₂ highlight significant socio-economic inequalities, with the most deprived populations disproportionately burdened by traffic-related air pollution. The results from our case-study to mitigate traffic-related air pollution demonstrate that, up to a Mobiscore of 8.0, car ownership remains constant with increasing availability of services and public transport. From a turning point Mobiscore of 8.0, car ownerships starts to drop significantly, indicating that improving Mobiscores to very high scores ( > = 8.0) may lead to reduced car ownership and lower NO2 and PM2.5 emissions and exposure. Our study highlights important spatial-seasonal patterns in air pollution and their health implications, emphasizing the need for season-specific and structural traffic interventions to meet WHO guidelines for PM2.5 and NO2 exposure. A case study on mitigating traffic-related air pollution identifies a threshold where sufficient public transport and service accessibility lead to a reduction in car ownership. Addressing socio-economic disparities is crucial, as these areas often face greater challenges in meeting WHO air pollution guidelines, particularly for NO₂.

Does Nonsteroidal Anti-inflammatory Drug Use Modify All-Cause and Cause-Specific Mortality Associated with PM2.5 and Its Components? A Nationally Representative Cohort Study (2007-2017)

Several studies reported that nonsteroidal anti-inflammatory drug (NSAID) use could alleviate subclinical effects of short-term exposure to fine particulate matter (PM2.5). However, whether chronic NSAID use could mitigate the long-term effects of PM2.5 and its components on population mortality has been unknown. Based on a national representative survey of 47,086 adults (2007-2010) with follow-up information on the primary cause of death (until 2017), we investigated the long-term associations of PM2.5 and its major components, including black carbon (BC), ammonium (NH4 +), nitrate (NO3 -), organic matter (OM), and sulfate (SO4 2-), with all-cause and cause-specific mortality using the Cox proportional hazards model. We also evaluated the effect modification by NSAID use (including broad NSAIDs, aspirin, or ibuprofen) on the associations using interaction models. Long-term exposures to PM2.5 and its components were associated with increased risks of all-cause and cause-specific mortality, where BC, OM, and SO4 2- showed stronger associations. Ibuprofen use could mitigate the associations of PM2.5 and its components with mortality risks, while no significant modifying effects of aspirin were observed. For instance, along with per interquartile range increment in PM2.5 concentration (34.8 μg/m3), the hazard ratios (HRs) of all-cause mortality were 1.21 (95% CI: 1.19, 1.22) and 1.10 (95% CI: 1.01, 1.19) in nonibuprofen and ibuprofen use groups (P for interaction = 0.026), respectively. Cause-specific analyses indicated that ibuprofen use could mainly mitigate risks of cardiovascular disease (CVD) especially ischemic heart disease (IHD) mortality attributable to PM2.5 components. Stratified analyses found more apparent mitigating effects of ibuprofen use among participants without chronic diseases, participants ≤50 years, female participants, rural residents, and those with lower education levels. Our findings suggested potential implications in reducing population mortality caused by long-term exposures to PM2.5 and its components through personalized interventions.

The association between ambient PM2.5's constituents exposure and cervical cancer survival

Increasing evidence links exposure to ambient particulate matter with a diameter less than 2.5 μm (PM2.5) with reduced survival in cancer survivors, but little was known about the association between PM2.5 exposure and cervical cancer survival. We analyzed data from 5144 cervical cancer patients diagnosed between January 2014 and December 2020, who completed recommended treatments. Exposure levels were determined by the monthly average concentration of ambient PM2.5 and its five constituents, obtained from Tracking Air Pollution in China (TAP) based on individual residential addresses. Log-rank tests and multivariate Cox Proportional Hazardous regression were performed to examine the impacts of PM2.5 and its constituents on overall survival (OS) of cervical cancer patients. We observed that for every increase of 1 μg/m3 in average individual exposure, the hazard ratios (95%CI) for ambient PM2.5, sulfate (SO42-), ammonium (NH4+), and nitrates (NO3-) were 1.078(1.069-1.086), 6.755(5.707-7.996), 2.123(1.935-2.329), and 3.717(3.237-4.267), respectively. Subgroups with longer OS had larger HRs of PM2.5 and its constituents, which might attributed to more cumulative exposure. No evidence of a threshold for the hazardous effects of PM2.5 on the OS of cervical cancer patients was identified. Furthermore, long-term exposure to PM2.5 was negatively associated with pretreatment counts of monocytes, neutrophils, and lymphocytes in peripheral blood of cervical cancer patients. In conclusion, elevated levels of PM2.5 mass, SO42-, NH4+, and NO3- in ambient PM2.5 exposure were associated with reduced OS among cervical cancer patients. There may be no discernible threshold effect of PM2.5 on the risk for cervical cancer patients.

Association of acute exposure to PM2.5 constituents and sources with kidney injury: A longitudinal panel study of Nrf2 promoter polymorphism

Evidence on the effects of fine particulate matter (PM2.5) constituents and sources on kidney injury is limited. We designed a panel study with 4 repeated measurements to investigate the association of acute exposure to chemical constituents and source-specific PM2.5 with kidney function and renal tubular injury. We further evaluated the modifying effect of Nrf2 promoter polymorphism. In this study, a total of 64 participants were recruited and ambient PM2.5 constituents were monitored at a fixed-site station. We used a positive matrix factorization (PMF) model to identify emission sources and linear mixed-effect models to explore the associations. An interquartile range (IQR) increase in PM2.5 concentration was associated with a 1.40 % and 3.15 % decrease in eGFR-Cr (eGFR assessed by creatinine) and eGFR-Cys (eGFR assessed by cystatin-C), respectively, and 10.2 % higher kidney injury molecule 1 (KIM-1) levels. Carbonaceous components (EC and OC), metallic elements (Cr, K, Pb, Zn) and Cl- were robustly responsible for kidney injury. Per IQR increase in these constituents accounted for 0.57 % to 1.62 % declines in eGFR-Cr; 1.36 % to 3.66 % declines in eGFR-Cys; and 7.50 % to 19.83 % increments in KIM-1. Specific source analysis revealed that PM2.5 emitted by combustion was associated with the largest reduction in eGFR, while the secondary source played a more prominent role in renal tubular injury. The dominant models showed that the magnitudes of the effect estimates of PM2.5 and its constituents were generally larger in the participants with minor alleles of the Nrf2 promoter. These findings suggest that acute exposure to EC, OC, Cl- and several metallic constituents may be responsible for kidney injury induced by PM2.5, especially in individuals with unfavorable Nrf2 genotypes. PM2.5 from combustion and secondary sources impairs kidney health, highlighting the importance of source-oriented PM2.5 control strategies.

Potential causal links of long-term exposure to PM2.5 and its chemical components with the risk of nasopharyngeal carcinoma recurrence: A 10-year cohort study in South China

There is a lack of evidence from cohort studies on the causal association of long-term exposure to ambient fine particulate matter (PM2.5) and its chemical components with the risk of nasopharyngeal carcinoma (NPC) recurrence. Based on a 10-year prospective cohort of 1184 newly diagnosed NPC patients, we comprehensively evaluated the potential causal links of ambient PM2.5 and its chemical components including black carbon (BC), organic matter (OM), sulfate (SO4 2-), nitrate (NO3 -), and ammonium (NH4 +) with the recurrence risk of NPC using a marginal structural Cox model adjusted with inverse probability weighting. We observed 291 NPC patients experiencing recurrence during the 10-year follow-up and estimated a 33% increased risk of NPC recurrence (hazard ratio [HR]: 1.33, 95% confidence interval [CI]: 1.02-1.74) following each interquartile range (IQR) increase in PM2.5 exposure. Each IQR increment in BC, NH4 +, OM, NO3 -, and SO4 2- was associated with HRs of 1.36 (95%CI: 1.13-1.65), 1.35 (95%CI: 1.07-1.70), 1.33 (95%CI: 1.11-1.59), 1.32 (95%CI: 1.06-1.64), 1.31 (95%CI: 1.08-1.57). The elderly, patients with no family history of cancer, no smoking history, no drinking history, and those with severe conditions may exhibit a greater likelihood of NPC recurrence following exposure to PM2.5 and its chemical components. Additionally, the effect estimates of the five components are greater among patients who were exposed to high concentration than in the full cohort of patients. Our study provides solid evidence for a potential relationship between long-term exposure to PM2.5 and its components and the risk of NPC recurrence.

Stillbirths Associated with Particle Pollution are Disproportionally Contributed by Sand Dust: Findings from 52 Low- and Middle-Income Countries

Whether maternal exposure to dust-sourced particulate matter (hereafter, dust PM2.5) is associated with stillbirth remains unknown. We adopted a sibling-matched case-control design to analyze 9332 stillbirths and 17,421 live births. We associated the risk of stillbirth simultaneously with dust and nondust components of PM2.5 and developed a nonlinear joint exposure-response function. Next, we estimated the burden of stillbirths attributable to the PM2.5 mixture. The concentration index was used to evaluate whether the burden of PM2.5-related stillbirths was disproportionally distributed among pregnancies exposed to dust-rich particles. Each 10 μg/m3 increase in dust PM2.5 was associated with a 14.5% (95% confidence interval: 5.5, 24.2%) increase in the odds of stillbirth. Based on the risk assessment across 137 countries, sand dust contributed to about 15% of the PM2.5 exposure but to about 45% of the PM2.5-related stillbirths during 2003-2019. In 2015, 30% of the PM2.5-related stillbirths were concentrated within 15% of pregnancies exposed to the dust-richest PM2.5. The index increased in subregions, such as South Asia, suggesting the growth of health inequality due to exposure to dust PM2.5. Based on our findings, land management, such as halting desertification, will help prevent stillbirths and reduce global maternal health inequality.

Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: The HEI Experience and What's Next?

Although concentrations of ambient air pollution continue to decline in high-income regions, epidemiological studies document adverse health effects at levels below current standards in many countries. The Health Effects Institute (HEI) recently completed a comprehensive research initiative to investigate the health effects of long-term exposure to low levels of air pollution in the United States (U.S.), Canada, and Europe. We provide an overview and synthesis of the results of this initiative along with other key research, the strengths and limitations of the research, and remaining research needs. The three studies funded through the HEI initiative estimated the effects of long-term ambient exposure to fine particulate matter (PM2.5), nitrogen dioxide, ozone, and other pollutants on a broad range of health outcomes, including cause-specific mortality and cardiovascular and respiratory morbidity. To ensure high quality research and comparability across studies, HEI worked actively with the study teams and engaged independent expert panels for project oversight and review. All three studies documented positive associations between mortality and exposure to PM2.5 below the U.S. National Ambient Air Quality Standards and current and proposed European Union limit values. Furthermore, the studies observed nonthreshold linear (U.S.), or supra-linear (Canada and Europe) exposure-response functions for PM2.5 and mortality. Heterogeneity was found in both the magnitude and shape of this association within and across studies. Strengths of the studies included the large populations (7-69 million), state-of-the-art exposure assessment methods, and thorough statistical analyses that applied novel methods. Future work is needed to better understand potential sources of heterogeneity in the findings across studies and regions. Other areas of future work include the changing and evolving nature of PM components and sources, including wildfires, and the role of indoor environments. This research initiative provided important new evidence of the adverse effects of long-term exposures to low levels of air pollution at and below current standards, suggesting that further reductions could yield larger benefits than previously anticipated.

Long-term exposure to air pollution and chronic kidney disease-associated mortality-Results from the pooled cohort of the European multicentre ELAPSE-study

Despite the known link between air pollution and cause-specific mortality, its relation to chronic kidney disease (CKD)-associated mortality is understudied. Therefore, we investigated the association between long-term exposure to air pollution and CKD-related mortality in a large multicentre population-based European cohort. Cohort data were linked to local mortality registry data. CKD-death was defined as ICD10 codes N18-N19 or corresponding ICD9 codes. Mean annual exposure at participant's home address was determined with fine spatial resolution exposure models for nitrogen dioxide (NO2), black carbon (BC), ozone (O3), particulate matter ≤2.5 μm (PM2.5) and several elemental constituents of PM2.5. Cox regression models were adjusted for age, sex, cohort, calendar year of recruitment, smoking status, marital status, employment status and neighbourhood mean income. Over a mean follow-up time of 20.4 years, 313 of 289,564 persons died from CKD. Associations were positive for PM2.5 (hazard ratio (HR) with 95% confidence interval (CI) of 1.31 (1.03-1.66) per 5 μg/m3, BC (1.26 (1.03-1.53) per 0.5 × 10- 5/m), NO2 (1.13 (0.93-1.38) per 10 μg/m3) and inverse for O3 (0.71 (0.54-0.93) per 10 μg/m3). Results were robust to further covariate adjustment. Exclusion of the largest sub-cohort contributing 226 cases, led to null associations. Among the elemental constituents, Cu, Fe, K, Ni, S and Zn, representing different sources including traffic, biomass and oil burning and secondary pollutants, were associated with CKD-related mortality. In conclusion, our results suggest an association between air pollution from different sources and CKD-related mortality.

Air pollution from biomass burning disrupts early adolescent cortical microarchitecture development

Exposure to outdoor particulate matter (PM2.5) represents a ubiquitous threat to human health, and particularly the neurotoxic effects of PM2.5 from multiple sources may disrupt neurodevelopment. Studies addressing neurodevelopmental implications of PM exposure have been limited by small, geographically limited samples and largely focus either on macroscale cortical morphology or postmortem histological staining and total PM mass. Here, we leverage residentially assigned exposure to six, data-driven sources of PM2.5 and neuroimaging data from the longitudinal Adolescent Brain Cognitive Development Study (ABCD Study®), collected from 21 different recruitment sites across the United States. To contribute an interpretable and actionable assessment of the role of air pollution in the developing brain, we identified alterations in cortical microstructure development associated with exposure to specific sources of PM2.5 using multivariate, partial least squares analyses. Specifically, average annual exposure (i.e., at ages 8-10 years) to PM2.5 from biomass burning was related to differences in neurite development across the cortex between 9 and 13 years of age.

Air pollution from biomass burning disrupts early adolescent cortical microarchitecture development

Exposure to outdoor particulate matter (PM 2.5 ) represents a ubiquitous threat to human health, and particularly the neurotoxic effects of PM 2.5 from multiple sources may disrupt neurodevelopment. Studies addressing neurodevelopmental implications of PM exposure have been limited by small, geographically limited samples and largely focus either on macroscale cortical morphology or postmortem histological staining and total PM mass. Here, we leverage residentially assigned exposure to six, data-driven sources of PM 2.5 and neuroimaging data from the longitudinal Adolescent Brain Cognitive Development Study (ABCD Study®), collected from 21 different recruitment sites across the United States. To contribute an interpretable and actionable assessment of the role of air pollution in the developing brain, we identified alterations in cortical microstructure development associated with exposure to specific sources of PM 2.5 using multivariate, partial least squares analyses. Specifically, average annual exposure (i.e., at ages 8-10 years) to PM 2.5 from biomass burning was related to differences in neurite development across the cortex between 9 and 13 years of age.

Long-term exposure to several constituents and sources of PM2.5 is associated with incidence of upper aerodigestive tract cancers but not gastric cancer: Results from the large pooled European cohort of the ELAPSE project

It is unclear whether cancers of the upper aerodigestive tract (UADT) and gastric cancer are related to air pollution, due to few studies with inconsistent results. The effects of particulate matter (PM) may vary across locations due to different source contributions and related PM compositions, and it is not clear which PM constituents/sources are most relevant from a consideration of overall mass concentration alone. We therefore investigated the association of UADT and gastric cancers with PM2.5 elemental constituents and sources components indicative of different sources within a large multicentre population based epidemiological study. Cohorts with at least 10 cases per cohort led to ten and eight cohorts from five countries contributing to UADT- and gastric cancer analysis, respectively. Outcome ascertainment was based on cancer registry data or data of comparable quality. We assigned home address exposure to eight elemental constituents (Cu, Fe, K, Ni, S, Si, V and Zn) estimated from Europe-wide exposure models, and five source components identified by absolute principal component analysis (APCA). Cox regression models were run with age as time scale, stratified for sex and cohort and adjusted for relevant individual and neighbourhood level confounders. We observed 1139 UADT and 872 gastric cancer cases during a mean follow-up of 18.3 and 18.5 years, respectively. UADT cancer incidence was associated with all constituents except K in single element analyses. After adjustment for NO2, only Ni and V remained associated with UADT. Residual oil combustion and traffic source components were associated with UADT cancer persisting in the multiple source model. No associations were found for any of the elements or source components and gastric cancer incidence. Our results indicate an association of several PM constituents indicative of different sources with UADT but not gastric cancer incidence with the most robust evidence for traffic and residual oil combustion.

Elegant Nematodes Improve Our Understanding of Human Neuronal Diseases, the Role of Pollutants and Strategies of Resilience

The prevalence of neurodegenerative disorders such as Alzheimer's and Parkinson's disease are rising globally. The role of environmental pollution in neurodegeneration is largely unknown. Thus, this perspective advocates exposome research in C. elegans models of human diseases. The models express amyloid proteins such as Aβ, recapitulate the degeneration of specifically vulnerable neurons and allow for correlated neurobehavioral phenotyping throughout the entire life span of the nematode. Neurobehavioral traits like locomotion gaits, rigidity, or cognitive decline are quantifiable and carefully mimic key aspects of the human diseases. Underlying molecular pathways of neurodegeneration are elucidated in pollutant-exposed C. elegans Alzheimer's or Parkinson's models by transcriptomics (RNA-seq), mass spectrometry-based proteomics and omics addressing other biochemical traits. Validation of the identified disease pathways can be achieved by genome-wide association studies in matching human cohorts. A consistent One Health approach includes isolation of nematodes from contaminated sites and their comparative investigation by imaging, neurobehavioral profiling and single worm proteomics. C. elegans models of neurodegenerative diseases are likewise well-suited for high throughput methods that provide a promising strategy to identify resilience pathways of neurosafety and keep up with the number of pollutants, nonchemical exposome factors, and their interactions.

Long-term exposure to low-concentration PM2.5 and heart disease in older men in Perth, Australia: The Health in Men Study

Exposure to particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5) is associated with increased risk of heart disease, but less is known about the relationship at low concentrations. This study aimed to determine the dose-response relationship between long-term PM2.5 exposure and risk of incident ischemic heart disease (IHD), incident heart failure (HF), and incident atrial fibrillation (AF) in older men living in a region with relatively low ambient air pollution.

Methods

PM2.5 exposure was estimated for 11,249 older adult males who resided in Perth, Western Australia and were recruited from 1996 to 1999. Participants were followed until 2018 for the HF and AF outcomes, and until 2017 for IHD. Cox-proportional hazards models, using age as the analysis time, and adjusting for demographic and lifestyle factors were used. PM2.5 was entered as a restricted cubic spline to model nonlinearity.

Results

We observed a mean PM2.5 concentration of 4.95 μg/m3 (SD 1.68 μg/m3) in the first year of recruitment. After excluding participants with preexisting disease and adjusting for demographic and lifestyle factors, PM2.5 exposure was associated with a trend toward increased incidence of IHD, HF, and AF, but none were statistically significant. At a PM2.5 concentration of 7 μg/m3 the hazard ratio for incident IHD was 1.04 (95% confidence interval [CI] = 0.86, 1.25) compared with the reference category of 1 μg/m3.

Conclusions

We did not observe a significant association between long-term exposure to low-concentration PM2.5 air pollution and IHD, HF, or AF.

Spatial and sector-specific contributions of emissions to ambient air pollution and mortality in European cities: a health impact assessment

BACKGROUND

Ambient air pollution is a major risk to health and wellbeing in European cities. We aimed to estimate spatial and sector-specific contributions of emissions to ambient air pollution and evaluate the effects of source-specific reductions in pollutants on mortality in European cities to support targeted source-specific actions to address air pollution and promote population health.

METHODS

We conducted a health impact assessment of data from 2015 for 857 European cities to estimate source contributions to annual PM_2·5 and NO₂ concentrations using the Screening for High Emission Reduction Potentials for Air quality tool. We evaluated contributions from transport, industry, energy, residential, agriculture, shipping, and aviation, other, natural, and external sources. For each city and sector, three spatial levels were considered: contributions from the same city, the rest of the country, and transboundary. Mortality effects were estimated for adult populations (ie, ≥20 years) following standard comparative risk assessment methods to calculate the annual mortality preventable on spatial and sector-specific reductions in PM_2·5 and NO₂.

FINDINGS

We observed strong variability in spatial and sectoral contributions among European cities. For PM_2·5, the main contributors to mortality were the residential (mean contribution of 22·7% [SD 10·2]) and agricultural (18·0% [7·7]) sectors, followed by industry (13·8% [6·0]), transport (13·5% [5·8]), energy (10·0% [6·4]), and shipping (5·5% [5·7]). For NO₂, the main contributor to mortality was transport (48·5% [SD 15·2]), with additional contributions from industry (15·0% [10·8]), energy (14·7% [12·9]), residential (10·3% [5·0]), and shipping (9·7% [12·7]). The mean city contribution to its own air pollution mortality was 13·5% (SD 9·9) for PM_2·5 and 34·4% (19·6) for NO₂, and contribution increased among cities of largest area (22·3% [12·2] for PM_2·5 and 52·2% [19·4] for NO₂) and among European capitals (29·9% [12·5] for PM_2·5 and 62·7% [14·7] for NO₂).

INTERPRETATION

We estimated source-specific air pollution health effects at the city level. Our results show strong variability, emphasising the need for local policies and coordinated actions that consider city-level specificities in source contributions.

FUNDING

Spanish Ministry of Science and Innovation, State Research Agency, Generalitat de Catalunya, Centro de Investigación Biomédica en red Epidemiología y Salud Pública, and Urban Burden of Disease Estimation for Policy Making 2023-2026 Horizon Europe project.

Source sectors underlying PM2.5-related deaths among children under 5 years of age in 17 low- and middle-income countries

BACKGROUND

Fine particulate matter (PM_2.5) from different source sectors might differ in toxicity. However, data from large-scale studies on vulnerable children in low- and middle-income countries (LMICs) are insufficient.

OBJECTIVE

To analyze the association of under-five death (U5D) with long-term exposure to PM_2.5 from different sources.

METHOD

We evaluated demographic and health survey data for 79,995 babies born in 2017 in 16 Asian and African LMICs (AA-LMICs) and a Latin America low-income country (i.e., Haiti). Long-term exposure to PM_2.5 was assessed by a well-established product that attributed the annual concentration to 20 source sectors in 2017. The associations of survival during < 5-year periods with each source-specific concentration of PM_2.5 were analyzed by Cox regression with multiple adjustments. We derived a multiple-pollutant ridge regression model to estimate the joint exposure-response function (JERF) between U5D and PM_2.5 mixtures. To evaluate how sources affected PM_2.5 toxicity, we evaluated the number of U5Ds attributable to PM_2.5 based on the source profiles for 88 AA-LMICs.

RESULTS

According to the single-pollutant model, the risk of U5D increased by 7% (95% confidence interval [CI]: 5%, 9%) for each 10 μg/m³ increment in total PM_2.5 concentration. The model performance was lower than that of the multiple-pollutant ridge regression model. For each 10 μg/m³ increment in PM_2.5, the excess risk of U5D ranged from 6% (95% CI: 4%, 9%) in Nepal to 10% (95% CI: 6%, 14%) in Mauritania. Based on the JERF, PM_2.5 contributed to 817,647 (95% CI: 585,729, 1,050,439), i.e., 28.0% (95% CI: 20.1%, 35.8%), of all U5Ds across the 88 AA-LMICs. The PM_2.5-related U5Ds were mostly attributable to PM_2.5 produced by desert dust, followed by solid biofuel combustion and open fires.

CONCLUSION

The average toxicity of PM_2.5 varied by source profile, which should be taken into consideration when planning public health interventions. For some AA LMICs, natural sources of PM_2.5 had the most significant health effects, and should not be ignored to ensure the protection of child health.

Evaluating the influence of constant source profile presumption on PMF analysis of PM2.5 by comparing long- and short-term hourly observation-based modeling

Hourly PM_2.5 speciation data have been widely used as an input of positive matrix factorization (PMF) model to apportion PM_2.5 components to specific source-related factors. However, the influence of constant source profile presumption during the observation period is less investigated. In the current work, hourly concentrations of PM_2.5 water-soluble inorganic ions, bulk organic and elemental carbon, and elements were obtained at an urban site in Nanjing, China from 2017 to 2020. PMF analysis based on observation data during specific pollution (firework combustion, sandstorm, and winter haze) and emission-reduction (COVID-19 pandemic) periods was compared with that using the whole 4-year data set (PMF_whole). Due to the lack of data variability, event-based PMF solutions did not separate secondary sulfate and nitrate. But they showed better performance in simulating average concentrations and temporal variations of input species, particularly for primary source markers, than the PMF_whole solution. After removing event data, PMF modeling was conducted for individual months (PMF_month) and the 4-year period (PMF_4-year), respectively. PMF_month solutions reflected varied source profiles and contributions and reproduced monthly variations of input species better than the PMF_4-year solution, but failed to capture seasonal patterns of secondary salts. Additionally, four winter pollution days were selected for hour-by-hour PMF simulations, and three sample sizes (500, 1000, and 2000) were tested using a moving window method. The results showed that using short-term observation data performed better in reflecting immediate changes in primary sources, which will benefit future air quality control when primary PM emissions begin to increase.

How the Air Clean Plan and carbon mitigation measures co-benefited China in PM2.5 reduction and health from 2014 to 2020

China implemented a stringent Air Clean Plan (ACP) since 2013 to address environmental and health risks caused by ambient fine particulate matter (PM_2.5). However, the policy effectiveness of ACP and co-benefits of carbon mitigation measures to environment and health are still largely unknown. Using satellite-based PM_2.5 products produced in our previous study, concentration-response functions, and the logarithmic mean Divisia index (LMDI) method, we analyzed the spatiotemporal dynamics of premature deaths attributable to PM_2.5 exposure, and quantitatively estimated the policy benefits of ACP and carbon mitigation measures. We found the annual PM_2.5 concentrations in China decreased by 33.65 % (13.41 μg m^-3) from 2014 to 2020, accompanied by a decrease in PM_2.5-attributable premature deaths of 0.23 million (95 % confidence interval (CI): 0.22-0.27), indicating the huge benefits of China ACP for human health and environment. However, there were still 1.12 million (95 % CI: 0.79-1.56) premature deaths caused by the exposure of PM_2.5 in mainland China in 2020. Among all ACP measures, clean production (contributed 55.98 % and 51.14 % to decrease in PM_2.5 and premature deaths attributable to PM_2.5) and energy consumption control (contributed 32.58 % and 29.54 % to decrease in PM_2.5 and premature deaths attributable to PM_2.5) made the largest contribution during the past seven years. Nevertheless, the environmental and health benefits of ACP are not fully synergistic in different regions, and the effectiveness of ACP measures reduced from 2018 to 2020. The co-effects of CO₂ and PM_2.5 has become one of the major drivers for PM_2.5 and premature deaths reduction since 2018, confirming the clear environment and health co-benefits of carbon mitigation measures. Our study suggests, with the saturation of clean production and source control, more targeted region-specific strategies and synergistic air pollution-carbon mitigation measures are critical to achieving the WHO's Air Quality Guideline target and the UN's Sustainable Development Goal Target in China.