Implementing the US air quality standard for PM2.5 worldwide can prevent millions of premature deaths per year

Estimation of PM2.5 using high-resolution satellite data and its mortality risk in an area of Iran

Satellite-based exposure of fine particulate matters has been seldom used as a predictor of mortality. PM2.5 was predicted using Aerosol Optical Depths (AOD) through a two-stage regression model. The predicted PM2.5 was corrected for the bias using two approaches. We estimated the impact by two different scenarios of PM2.5 in the model. We statistically found different distributions of the predicted PM2.5 over the region. Compared to the reference value (5 µg/m3), 90th and 95th percentiles had significant adverse effect on total mortality (RR 90th percentile:1.45; CI 95%: 1.08-1.95 and RR 95th percentile:1.53; CI 95%: 1.11-2.1). Nearly 1050 deaths were attributed to any range of the air pollution (unhealthy range), of which more than half were attributed to high concentration range. Given the adverse effect of extreme values compared to the both scenarios, more efforts are suggested to define local-specific reference values and preventive strategies.

Anthropological responses to environmental challenges in SAARC nations: A comparative analysis

The purpose of the study is to investigate the relationships and potential impacts of environmental pollutants, human resources, GDP, sustainable power sources, financial assets, and SAARC countries from 1995 to 2022. Board cointegration tests, D-H causality, cross-sectional reliance (CSD), Saville and Holdsworth Restricted (SHL), and the DSK Appraisal Strategy were among the logical techniques employed to discover long-term connections between these components. Results demonstrate that GDP growth, renewable energy sources (REC), and environmental pollution (ENP) all contribute to SAARC countries' progress. However, future opportunities and HR are negatively impacted by increased ecological pollution. The results of the two-way causality test demonstrate a strong correlation between HR and future possibilities. Opportunities for the SAARC countries are closely related to the growth of total national output, the use of green electricity, and public support sources. Ideas for tackling future projects are presented in the paper's conclusion. These include facilitating financial development, reducing ecological pollution, financing the progress of human resources, and promoting the use of sustainable power sources.

Cigarette smoking and air pollution exposure and their effects on cardiovascular diseases

Cardiovascular disease (CVD) has no socioeconomic, topographical, or sex limitations as reported by the World Health Organization (WHO). The significant drivers of CVD are cardio-metabolic, behavioral, environmental, and social risk factors. However, some significant risk factors for CVD (e.g., a pitiable diet, tobacco smoking, and a lack of physical activities), have also been linked to an elevated risk of cardiovascular disease. Lifestyles and environmental factors are known key variables in cardiovascular disease. The familiarity with smoke goes along with the contact with the environment: air pollution is considered a source of toxins that contribute to the CVD burden. The incidence of myocardial infarction increases in males and females and may lead to fatal coronary artery disease, as confirmed by epidemiological studies. Lipid modification, inflammation, and vasomotor dysfunction are integral components of atherosclerosis development and advancement. These aspects are essential for the identification of atherosclerosis in clinical investigations. This article aims to show the findings on the influence of CVD on the health of individuals and human populations, as well as possible pathology and their involvement in smoking-related cardiovascular diseases. This review also explains lifestyle and environmental factors that are known to contribute to CVD, with indications suggesting an affiliation between cigarette smoking, air pollution, and CVD.

Health benefits from risk information of air pollution in China

Risk-related information regarding air pollution can help people understand the risk involved and take preventive measures to reduce health loss. However, the health benefits through these protective behaviors and the health threat of information inequality have not been systematically measured. This article reports the health gains and losses caused by the interaction of "air pollution-air pollution information-human", and studies the heterogeneity and impact of this interaction. Based on field investigations and transfer learning algorism, this study compiled the first nationwide city-level risk-related information (ERI) response parameter set in China. Then, we developed a Information-Behavioral Equivalent PM2.5 Exposure Model (I-BEPEM) model to project the health benefits caused by the impact of environmental risk-related information on residents' protective behaviors under different scenarios. The protective behavior led by air pollution risk information reduces 5.7% PM2.5-related premature deaths per year. With a 1% increase in regional ERI reception, PM2.5-related premature mortality decreases by 0.1% on average; If the level of information perception and behavioral protection in all cities is the same as that in Beijing, PM2.5-related premature deaths will decrease by 6.9% annually in China. Further, changing the air quality standard issued by China to the American standard can reduce the overall PM2.5-related premature deaths by 9.9%. Meanwhile, compared with men, other age groups and rural residents, women, older persons, and urban residents are more likely to conceive risk information and adopt protective behaviors to reduce the risk of premature death from air pollution. Air pollution risk information can significantly reduce people's health loss. Changing the real-time air quality monitoring information indicator standard to a more stringent level can quickly and effectively enhance this effect. However, the uneven distribution of this information in regions and populations has resulted in the inequality of health gains and losses.

Global, regional, and national burden of preterm birth attributable to ambient and household PM2.5 from 1990 to 2019: Worsening or improving?

BACKGROUND

Maternal exposure to fine particular matter (PM_2.5) during pregnancy, including ambient and household PM_2.5, has been linked with increased risk of preterm birth (PTB). However, the global spatio-temporal distribution of PTB-related deaths and disability-adjusted life years (DALYs) attributable to PM_2.5 is not well documented. We estimated the global, regional, and national patterns and trends of PTB burden attributable to both ambient and household PM_2.5 from 1990 to 2019.

METHODS

Based on the Global Burden of Disease Study (GBD) 2019 database, we obtained the numbers of deaths and DALYs as well as age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) of PTB attributable to total, ambient, and household PM_2.5 by socio-demographic index (SDI) and sex during 1990-2019. The average annual percentage changes (AAPCs) were calculated to assess the temporal trends of attributable burdens.

RESULTS

In 2019, 126,752 deaths and 11.3 million DALYs related to PTB worldwide (two-thirds in Western Sub-Saharan Africa and South Asia) could be caused by excess PM_2.5 above the theoretical minimum-risk exposure level (TMREL), of which 39 % and 61 % were attributable to ambient PM_2.5 and household PM_2.5, respectively. From 1990 to 2019, the global ASMR due to ambient PM_2.5 increased slightly by 7.08 % whereas that due to household PM_2.5 decreased substantially by 58.81 %, although the latter still dominated the attributable PTB burden, especially in low and low-middle SDI regions. Similar results were also observed for ASDRs. In addition, PTB burden due to PM_2.5 was higher in male infants and in lower SDI regions.

CONCLUSIONS

Globally in 2019, PM_2.5 remains a great concern on the PTB burden, especially in Western Sub-Saharan Africa and South Asia. Between 1990 and 2019, age-standardized burden of PTB due to ambient PM_2.5 increased globally, while that due to household PM_2.5 decreased markedly but still dominated in low and low-middle SDI regions.

Potential health and economic impacts of shifting manufacturing from China to Indonesia or India

The diversification or decoupling of production chains from China to alternative Asian countries such as India or Indonesia would impact the spatial distribution of anthropogenic emissions, with corresponding economic impacts due to mortality associated with particulate matter exposure. We evaluated these changes using the Community Earth System Model, the Integrated Exposure-Response (IER) model and Willingness To Pay (WTP) method. Significant effects on PM_2.5 related mortality and economic cost for these deaths were seen in many East, Southeast and South Asian countries, particularly those immediately downwind of these three countries. Transferring all of export-related manufacturing to Indonesia resulted in significant mortality decreases in China and South Korea by 78k (5 per 100k) and 1k (2 per 100k) respectively, while Indonesia's mortality significantly increased (73.7k; 29 per 100k), as well as India, Pakistan and Nepal. When production was transferred to India, mortality rates in East Asia show similar changes to the Indonesian scenario, while mortalities in India increased dramatically (87.9k; 6 per 100k), and mortalities in many neighbors of India were also severely increased. Nevertheless, the economic costs for PM_2.5 related mortality were much smaller than national GDP changes in China (0.9 % of GDP vs. 18.3 % of GDP), India (2.7 % of GDP vs. 84.3 % of GDP) or Indonesia (9.4 % of GDP vs. 337 % of GDP) due to shifting all of export-related production lines from China to India or Indonesia. Morally, part of the benefits of economic activity should be used to compensate the neighboring communities where mortality increases occur.

Pollution and cardiovascular health: A contemporary review of morbidity and implications for planetary health

Pollution is a leading cause of premature morbidity and mortality and an important risk factor for cardiovascular disease. Convincing data predict increased rates of cardiovascular morbidity and mortality with current and projected pollution burden trends. Multiple classes of pollutants - including criteria air pollutants, secondhand smoke, toxic steel pollutants, and manufactured chemical pollutants - are associated with varied cardiovascular disease risk profiles. To reduce the future risk of cardiovascular disease from anthropogenic pollution, mitigation strategies, both at the individual level and population level, must be thoughtfully and intentionally employed. The literature supporting individual level interventions to protect against cardiovascular disease is growing but lacks large clinical trials. Population level interventions are crucial to larger societal change and rely upon policy and governmental support. While these mitigation strategies can play a major role in maintaining the health of individuals, planetary health - the impact on human health because of anthropogenic perturbation of natural ecosystems - must also be acknowledged. Future research is needed to further delineate the planetary health implications of current and projected pollutant burden as well as the mitigation strategies employed to attenuate future pollutant burden.

Urban form and its impacts on air pollution and access to green space: A global analysis of 462 cities

A better understanding of urban form metrics and their environmental outcomes can help urban policymakers determine which policies will lead to more sustainable growth. In this study, we have examined five urban form metrics-weighted density, density gradient slope, density gradient intercept, compactness, and street connectivity-for 462 metropolitan areas worldwide. We compared urban form metrics and examined their correlations with each other across geographic regions and socioeconomic characteristics such as income. Using the K-Means clustering algorithm, we then developed a typology of urban forms worldwide. Furthermore, we assessed the associations between urban form metrics and two important environmental outcomes: green space access and air pollution. Our results demonstrate that while higher density is often emphasized as the way to reduce driving and thus PM2.5 emissions, it comes with a downside-less green space access and more exposure to PM2.5. Moreover, street connectivity has a stronger association with reduced PM2.5 emissions from the transportation sector. We further show that it is not appropriate to generalize urban form characteristics and impacts from one income group or geographical region to another, since the correlations between urban form metrics are context specific. Our conclusions indicate that density is not the only proxy for different aspects of urban form and multiple indicators such as street connectivity are needed. Our findings provide the foundation for future work to understand urban processes and identify effective policy responses.

Air quality impacts of crop residue burning in India and mitigation alternatives

Crop residue burning contributes to poor air quality and imposes a health burden on India. Despite government bans and other interventions, this practice remains widespread. Here we estimate the impact of changes in agricultural emissions on air quality across India and quantify the potential benefit of district-level actions using an adjoint modeling approach. From 2003 to 2019, we find that agricultural residue burning caused 44,000-98,000 particulate matter exposure-related premature deaths annually, of which Punjab, Haryana, and Uttar Pradesh contribute 67-90%. Due to a combination of relatively high downwind population density, agricultural output, and cultivation of residue-intensive crops, six districts in Punjab alone contribute to 40% of India-wide annual air quality impacts from residue burning. Burning two hours earlier in Punjab alone could avert premature deaths up to 9600 (95% CI: 8000-11,000) each year, valued at 3.2 (95% CI: 0.49-7.3) billion US dollars. Our findings support the use of targeted and potentially low-cost interventions to mitigate crop residue burning in India, pending further research regarding cost-effectiveness and feasibility.

Genomic Basis for Individual Differences in Susceptibility to the Neurotoxic Effects of Diesel Exhaust

Air pollution is a known environmental health hazard. A major source of air pollution includes diesel exhaust (DE). Initially, research on DE focused on respiratory morbidities; however, more recently, exposures to DE have been associated with neurological developmental disorders and neurodegeneration. In this study, we investigated the effects of sub-chronic inhalation exposure to DE on neuroinflammatory markers in two inbred mouse strains and both sexes, including whole transcriptome examination of the medial prefrontal cortex. We exposed aged male and female C57BL/6J (B6) and DBA/2J (D2) mice to DE, which was cooled and diluted with HEPA-filtered compressed air for 2 h per day, 5 days a week, for 4 weeks. Control animals were exposed to HEPA-filtered air on the same schedule as DE-exposed animals. The prefrontal cortex was harvested and analyzed for proinflammatory cytokine gene expression (Il1β, Il6, Tnfα) and transcriptome-wide response by RNA-seq. We observed differential cytokine gene expression between strains and sexes in the DE-exposed vs. control-exposed groups for Il1β, Tnfα, and Il6. For RNA-seq, we identified 150 differentially expressed genes between air and DE treatment related to natural killer cell-mediated cytotoxicity per Kyoto Encyclopedia of Genes and Genomes pathways. Overall, our data show differential strain-related effects of DE on neuroinflammation and neurotoxicity and demonstrate that B6 are more susceptible than D2 to gene expression changes due to DE exposures than D2. These results are important because B6 mice are often used as the default mouse model for DE studies and strain-related effects of DE neurotoxicity warrant expanded studies.

The global burden of disease attributable to ambient fine particulate matter in 204 countries and territories, 1990-2019: A systematic analysis of the Global Burden of Disease Study 2019

Understanding the spatio-temporal patterns of the disease burden attributable to ambient PM2.5 across the world is essential for the prevention of related diseases, as well as ambient PM2.5 control. Following the framework and methodology of the Global Burden of Disease Study (GBD) in 2019, the global, regional, and national data on ambient PM2.5-attributable death and disability-adjusted life years (DALYs), and the age-standardized rates of mortality (ASMR) and disability-adjusted life years (ASDR) were summarized based on age, gender, year, location and specific diseases. We calculated the average annual percentage change (AAPC) to depict the secular trends of ASMR and ASDR from 1990 to 2019. In 2019, the global ambient PM2.5-related deaths and DALYs were 4,140,970 and 118.2 million, respectively, with 1,702,150 deaths and 47.5 million DALYs for females and 2,438,820 deaths and 70.7 million DALYs for male. In the 13 level-three causes, ischemic heart disease, stroke, chronic obstructive and pulmonary disease (COPD) were the leading three causes of deaths and DALYs attributable to ambient PM2.5. The number of global deaths and DALYs attributable to ambient PM2.5 has increased by 102.3% and 67.7% from 1990 to 2019, respectively. However, ASMR and ASDR showed little change. In the 13 level-three diseases, ischemic heart disease, stroke, COPD, diabetes mellitus, and lung cancer were the top five contributors to the increase of global deaths or DALYs, among which diabetes mellitus had the fastest increase of ASMR and ASDR, with AAPC of 1.5 (95% CI: 1.43, 1.58) and 2.21 (95% CI: 2.15, 2.27), respectively. The population attributable fractions (PAF) of causes in ASMR or ASDR varied significantly across regions, of which PAF of COPD, stroke and lung cancer were the top three. Regarding the GBD region, high PAF mainly occurred in North Africa and Middle East, South Asia, and East Asia. The age-specific PAFs of ischemic heart disease and stroke deaths and DALYs due to ambient PM2.5 were negatively correlated with age. ASMR and ASDR of overall PM2.5 related-burden showed an inverted "V/U" relationship with the socio-demographic index (SDI). The AAPC of ASMR and ASDR of the overall causes showed a strong negative correlation with SDI in 2019, especially at the SDI larger than 0.5. The deaths and DALYs attributable to ambient PM2.5 continued to increase under the context of population growth and aging. Decision-makers should consider controlling the PM2.5 emission when developing the economy.

County-Wide Mortality Assessments Attributable to PM2.5 Emissions from Coal Consumption in Taiwan

Over one-third of energy is generated from coal consumption in Taiwan. In order to estimate the health impact assessment attributable to PM_2.5 concentrations emitted from coal consumption in Taiwan. We applied a Gaussian trajectory transfer-coefficient model to obtain county-wide PM_2.5 exposures from coal consumption, which includes coal-fired power plants and combined heat and power plants. Next, we calculated the mortality burden attributable to PM_2.5 emitted by coal consumption using the comparative risk assessment framework developed by the Global Burden of Disease study. Based on county-level data, the average PM_2.5 emissions from coal-fired plants in Taiwan was estimated at 2.03 ± 1.29 (range: 0.32–5.64) μg/m³. With PM_2.5 increments greater than 0.1 μg/m³, there were as many as 16 counties and 66 air quality monitoring stations affected by coal-fired plants and 6 counties and 18 monitoring stations affected by combined heat and power plants. The maximum distances affected by coal-fired and combined heat and power plants were 272 km and 157 km, respectively. Our findings show that more counties were affected by coal-fired plants than by combined heat and power plants with significant increments of PM_2.5 emissions. We estimated that 359.6 (95% CI: 334.8–384.9) annual adult deaths and 124.4 (95% CI: 116.4–132.3) annual premature deaths were attributable to PM_2.5 emitted by coal-fired plants in Taiwan. Even in six counties without power plants, there were 75.8 (95% CI: 60.1–91.5) deaths and 25.8 (95%CI: 20.7–30.9) premature deaths annually attributable to PM_2.5 emitted from neighboring coal-fired plants. This study presents a precise and effective integrated approach for assessing air pollution and the health impacts of coal-fired and combined heat and power plants.

Effects of aerosol particle size on the measurement of airborne PM2.5 with a low-cost particulate matter sensor (LCPMS) in a laboratory chamber

Previous validation studies found a good linear correlation between the low-cost particulate matter sensors (LCPMS) and other research grade particulate matter (PM) monitors. This study aimed to determine if different particle size bins of PM would affect the linear relationship and agreement between the Dylos DC1700 (LCPMS) particle count measurements (converted to PM2.5 mass concentrations) and the Grimm 11R (research grade instrument) mass concentration measurements. Three size groups of PM2.5 (mass median aerodynamic diameters (MMAD): < 1 µm, 1-2 µm, and > 2 µm) were generated inside a laboratory chamber, controlled for temperature and relative humidity, by dispersing sodium chloride crystals through a nebulizer. A linear regression comparing 1-min average PM2.5 particle counts from the Dylos DC1700 (Dylos) to the Grimm 11R (Grimm) mass concentrations was estimated by particle size group. The slope for the linear regression was found to increase as MMAD increased (< 1 µm, 0.75 (R2 = 0.95); 1-2 µm, 0.90 (R2 = 0.93); and > 2 µm, 1.03 (R2 = 0.94). The linear slopes were used to convert Dylos counts to mass concentration, and the agreement between converted Dylos mass and Grimm mass was estimated. The absolute relative error between converted Dylos mass and the Grimm mass was smaller in the < 1 µm group (16%) and 1-2 µm group (16%) compared to the > 2 µm group (32%). Therefore, the bias between converted Dylos mass and Grimm mass varied by size group. Future studies examining particle size bins over a wider range of coarse particles (> 2.5 µm) would provide useful information for accurately converting LCPMS counts to mass concentration.

Assessment of interrelationship between meteorology, air quality and COVID 19 cases in Gujarat state

In the present study, pollutants levels from March 1, 2020, to August 30, 2020, were compared with similar periods of 2019 to assess the impact of lockdown due to COVID 19 on the quality of air in 3 different cities of Gujarat, India named Ahmedabad, Gandhinagar, and Valsad. Data was collected from AccuWeather and Central Pollution Control Board website for study period. Data was analyzed by comparing air quality taking 2019 as reference and correlation matrix were developed for study sites. Lockdown resulted from COVID-19 has shown decline trends in pollutant concentration resulting in improved air quality in the study area. In the first city Ahmedabad, Gujarat an air pollutant parameter such as CO, PM_2.5, PM_10, NO₂, and SO₂ were reduced by 54%, 181%, 70%, 33%, and 103% respectively. Almost similar trends were observed in the rest of the two cities also i.e., Gandhinagar and Valsad. NO₂ level got reduced by a factor of 100% which can be associated with ban on vehicular movement. Correlation between the air pollutant and metrological variables with COVID-19 variables were also studied be developing correlation matrix. In Gandhinagar, a strong correlation was observed between carbon monoxide, and PM₁₀ with COVID-19, a moderate correlation between NO₂, and SO₂ with the COVID-19 variables, a week correlation was found between temperature and COVID-19, and no correlation is found between wind speed and COVID-19 variables.

Excess Morbidity and Mortality Associated with Air Pollution above American Thoracic Society Recommended Standards, 2017-2019

Rationale: Over the past year, the American Thoracic Society (ATS), led by its Environmental Health Policy Committee, has reviewed the most current air quality scientific evidence and has revised their recommendations to 8 µg/m³ and 25 µg/m³ for long- and short-term fine particulate matter (PM_2.5) and reaffirmed the recommendation of 60 ppb for ozone to protect the American public from the known adverse health effects of air pollution. The current EPA standards, in contrast, expose the American public to pollution levels that are known to result in significant morbidity and mortality. Objectives: To provide county-level estimates of annual air pollution-related health outcomes across the United States using the most recent federal air quality data, and to support the ATS's recent update to the long-term PM_2.5 recommended standard. This study is presented as part of the annual ATS/Marron Institute "Health of the Air" report. Methods: Daily air pollution values were obtained from the U.S. Environmental Protection Agency's (EPA) Air Quality System for monitored counties in the United States from 2017-2019. Concentration-response functions used in the EPA's regulatory review process were applied to pollution increments corresponding to differences between the rolling 3-year design values and ATS-recommended levels for long-term PM_2.5 (8 µg/m³), short-term PM_2.5 (25 µg/m³), and ground-level ozone (O₃; 60 ppb). Health impacts were estimated at the county level in locations with valid monitoring data. Results: Meeting ATS recommendations throughout the country prevents an estimated 14,650 (95% CI: 8,660 - 22,610) deaths; 2,950 (95% CI: 1,530 - 4,330) lung cancer incidence events; 33,100 (95% CI: 7,300 - 71,000) morbidities, and 39.8 million (95% CI: 14.6 - 63.3 million) impacted days annually (see Table 1). This prevents 11,850 more deaths; 2,580 more lung cancer incidence events; 25,400 more morbidities; and 27.2 million more impacted days than meeting EPA standards alone. Conclusions: Significant health benefits to be gained by U.S. communities that work to meet ATS-recommended air quality standards have now been identified under scenarios meeting the new ATS recommendation for long-term PM_2.5 (8 µg/m³). The "Health of the Air" report presents an opportunity for air quality managers to quantify local health burdens and EPA officials to update their standards to reflect the latest science.

Mitochondria damage in ambient particulate matter induced cardiotoxicity: Roles of PPAR alpha/PGC-1 alpha signaling

Particulate matter (PM) had been associated with cardiotoxicity, while the mechanism of toxicity has yet to be elucidated, with mitochondria dysfunction as a potential candidate. To investigate the potential cardiotoxic effects of ambient PM exposure and assess the damage to cardiac mitochondria, C57/B6 mice were exposed to filtered air or real ambient PM for three or six weeks. Furthermore, to reveal the role of peroxisome proliferators-activated receptor alpha (PPAR alpha) in PM exposure induced cardiotoxicity/mitochondria damage, animals were also co-treated with PPAR alpha agonist WY 14,643 or PPAR alpha antagonist GW 6471. Cardiotoxicity was assessed with echocardiography and histopathology, while mitochondria damage was evaluated with mitochondria membrane potential measurement and transmission electron microscopy. Potential impacts of PM exposure to PPAR alpha signaling were detected with co-immunoprecipitation and western blotting. The results indicated that exposure to ambient PM exposure induced cardiotoxicity in C57/B6 mice, including altered cardiac functional parameters and morphology. Cardiac mitochondria damage is detected, in the form of compromised mitochondria membrane potential and morphology. Molecular investigations revealed disruption of PPAR alpha interaction with peroxisome proliferator-activated receptor gamma coactivator-1A (PGC-1a) as well as altered expression levels of PPAR alpha downstream genes. Co-treatment with WY 14,643 alleviated the observed toxicities, while co-treatment with GW 6471 had mixed results, exaggerating most cardiotoxicity and mitochondrial damage endpoints but alleviating some cardiac functional parameters. Interestingly, WY 14,643 and GW 6471 co-treatment seemed to exhibit similar regulative effects towards PPAR alpha signaling in animals exposed to PM. In conclusion, ambient PM exposure indeed induced cardiotoxicity in C57/B6 mice, in which cardiac mitochondria damage and disrupted PPAR alpha signaling are contributors.

Estimation of excess mortality due to long-term exposure to PM2.5 in continental United States using a high-spatiotemporal resolution model

BACKGROUND

Exposure to fine particulate matter (<2.5 mm in aerodynamic diameter, PM_2.5) pollution, even at low concentrations is associated with increased mortality. Estimates of the magnitude of the effect of particulate air pollution on mortality are generally done on a coarse spatial scale, such as 0.5°, and may fail to capture small spatial differences in exposure and baseline rates, which can bias results and impede the ability to consider environmental justice. We estimated the burden of mortality attributable to long-term exposure to ambient PM_2.5 among adults in the Continental United States on a 1 km scale, in order to provide information for decision makers setting health priorities.

METHODS

We conducted a health impact assessment for 2015 using a model predicting U.S. PM_2.5 concentrations at a spatial resolution of 1 km cells. We applied a concentration-response curve from a recently published meta-analysis of long-term PM_2.5 mortality association which incorporates new findings at high and low PM_2.5 concentrations. We computed the change in deaths in each grid cell, based on its grid cell population, Zip code level baseline mortality rates, and exposure under two scenarios; a decrease of PM_2.5 exposure levels by 40% and a decrease of PM_2.5 exposure levels to the county minimum PM_2.5 concentrations.

RESULTS

We estimated the deaths would fall by 104,786 (95% CI 57,016-135,726) and 112,040 (95% CI 63,261-159,116) attributable to 40% reduction and reduction to the county minimum PM_2.5 concentrations_, respectively. The greatest mortality impact due to 40% reduction in PM_2.5 was observed in California with; 11,621 (95% CI; 7156-15,989) and Texas with; 9616 (95% CI; 5798-13,352) excess deaths attributable to annual mean PM_2.5 concentrations of 9.54 and 9.12 μg m^-3, respectively. Within city analyses showed substantial heterogeneity in risk. The estimated Attributable fraction (AF %) in locations with high PM_2.5 levels was 8.6% (95% CI 5.4-11.7) compared to the overall AF% of 4.9% (95% CI; 2.9-6.8). In comparison, results using county average PM_2.5 were smaller than the estimates from the 1 km PM_2.5 datasets. Similarly, estimates using county-level mortality rates were smaller than estimates based on Zip-code level mortality rates.

CONCLUSIONS

Our study provides evidence of major health benefits expected from reducing PM_2.5 exposure, even in regions with relatively low PM_2.5 concentrations. Spatial characteristics of exposure and baseline mortality (e.g., accuracy, scales, and variations) in disease burden studies can significantly impact the results.

The effect of air pollution on drivers' safety performance

Numerous studies have determined the adverse effects of air pollution on the health, welfare, and comfort of humans. More recently, the effects of air pollution on cognitive performance of humans are also focused. However, as a group in direct exposure to air pollution, drivers are rarely studied. The present study aims to evaluate the effect of air pollution on the performance of drivers. Their performance is evaluated by observing the number of recorded accidents. The effect of pollutant concentration (primarily PM_2.5) on the number of accidents is investigated in a case study in Tehran. The temperature inversion phenomenon is used as an instrumental variable in a two-stage least squares method. The results indicate that temperature inversion had a significant positive correlation with the concentration of pollutants. Considering temperature inversion as an instrumental variable for these pollutants, it is observed that 1 μg/m³ increase in concentration of PM_2.5, increased the number of accidents approximately by 4% in 1 day, for the range of parameters studied. No significant relationship was observed regarding the effect of NO₂ and CO on accidents during the study period.

Impact of OA on the Temperature Dependence of PM 2.5 in the Los Angeles Basin

Air quality policy in the Los Angeles megacity is a guidepost for other megacities. Over the last 2 decades, the policy has substantially reduced aerosol (OA) concentrations and the frequency of high aerosol events in the region. During this time, the emissions contributing to, and the temperature associated with, high aerosol events have changed. Early in the record, aerosol concentrations responded to a variety of different sources. We show that emission control has been effective with a strong decrease in temperature-independent sources. As a result, the response of aerosol to temperature has become a dominant feature of high aerosol events in the basin. The organic fraction of the aerosol (OA) increases with the temperature approaching 35% at 40 °C. We describe a simple conceptual model of aerosol in Los Angeles, illustrating how benzene, toluene, ethylbenzene, and xylenes (BTEX) and isoprene, along with molecules for which these are plausible surrogates such as monoterpenes, are sufficient to explain the observed temperature dependence of PM 2.5.

Air quality standards for the concentration of particulate matter 2.5, global descriptive analysis

OBJECTIVE

To compare ambient air quality standards for the mass concentration of aerosol particles smaller than approximately 2.5 μm (PM2.5) and exposure to these particles in national and regional jurisdictions worldwide.

METHODS

We did a review of government documents and literature on air quality standards. We extracted and summarized the PM2.5 concentration limits effective before July 2020, noting whether standards were enforced, voluntary or target. We compared averaging methods and permitted periods of time that standards may be exceeded. We made a descriptive analysis of PM2.5 standards by population, total area and population density of jurisdictions. We also compared data on actual PM2.5 air quality against the standards.

FINDINGS

We obtained data on standards from 62 jurisdictions worldwide, including 58 countries. Of the world's 136.06 million km2 land under national jurisdictions, 71.70 million km2 (52.7%) lack an official PM2.5 air quality standard, and 3.17 billion people live in areas without a standard. The existing standards ranged from 8 to 75 µg/m3, mostly higher than the World Health Organization guideline annual limit of < 10 µg/m3. The weakest PM2.5 standards were often exceeded, while the more stringent standards were often met. Several jurisdictions with the highest population density demonstrated compliance with relatively stringent standards.

CONCLUSION

The metrics used in PM2.5 ambient air quality standards should be harmonized worldwide to facilitate accurate assessment of risks associated with PM2.5 exposure. Population density alone does not preclude stringent PM2.5 standards. Modernization of standards can also include short-term standards to unmask PM2.5 fluctuations in high-pollution areas.

Insights on the biological role of ultrafine particles of size PM<0.25: A prospective study from New Delhi

When the total ambient PM_2.5 levels are several-fold higher than the recommended limit, it may be important to study the distributions of different sizes of particulate matter (PM). Here, we assess the distributions of various sizes of total PM_2.5 for 12 months (on a monthly basis) in New Delhi, India. Importantly, we found that ultrafine particles (i.e., particles <0.5 μm) contribute significantly to total PM_2.5. PM_<0.25 were the most cytotoxic particles to human lung epithelial cells in all the 12 months. In addition, PM_<0.25 were associated with significantly higher cytotoxicity per unit mass compared to other size fractions constituting PM_2.5. For any given size of PM, the amount of reactive oxygen species (ROS) generated per unit mass is higher for the month of March as compared to that for the rest of the months in the year. The higher ROS generations for all sizes of PM collected in the month of March was not explained by differences in their metal content values. Our data suggests the lack of correlation between total PM_2.5 levels and the highly cytotoxic PM_<0.25. In summary, this work establishes the need for policy changes to routinely monitor PM_<0.25 and the necessity to establish exposure limits for PM_<0.25, especially when the total PM_2.5 levels are breached.

Measurements of Local Sources of Particulates with a Portable Monitor along the Coast of an Insular City

The air quality of modern cities is considered an important factor for the quality of life of humans and therefore is being safeguarded by various international organizations, concentrating on the mass concentration of particulate matter (PM) with an aerodynamic diameter less than 10, 2.5 and 1 μm. However, the different physical and anthropogenic processes and activities within the city contribute to the rise of fine (<1 μm) and coarse (>1 μm) particles, directly impacting human health and the environment. In order to monitor certain natural and anthropogenic events, suspecting their significant contribution to PM concentrations, seven different events taking place on the coastal front of the city of Limassol (Cyprus) were on-site monitored using a portable PM instrument; these included both natural (e.g., dust event) and anthropogenic (e.g., cement factory, meat festival, tall building construction, tire factory, traffic jam, dust road) emissions taking place in spring and summer periods. The violations of the limits that were noticed were attributed mainly to the various anthropogenic activities taking place on-site, revealing once more the need for further research and continuous monitoring of air quality.

Biodegradable CA/CPB electrospun nanofibers for efficient retention of airborne nanoparticles

The increase of the industrialization process brought the growth of pollutant emissions into the atmosphere. At the same time, the demand for advances in aerosol filtration is evolving towards more sustainable technologies. Electrospinning is gaining notoriety, once it enables to produce polymeric nanofibers with different additives and also the obtaining of small pore sizes and fiber diameters; desirable features for air filtration materials. Therefore, this work aims to evaluate the filtration performance of cellulose acetate (CA) nanofibers and cationic surfactant cetylpyridinium bromide (CPB) produced by electrospinning technique for retention of aerosol nanoparticles. The pressure drop and collection efficiency measurements of sodium chloride (NaCl) aerosol particles (diameters from 7 to 300 nm) were performed using Scanning Mobility Particle Sizer (SMPS). The average diameter of the electrospun nanofibers used was 239 nm, ranging from 113 to 398 nm. Experimental results indicated that the nanofibers showed good permeability (10^-11 m²) and high-efficiency filtration for aerosol nanoparticles (about 100 %), which can include black carbon (BC) and the new coronavirus. The pressure drop was 1.8 kPa at 1.6 cm s^-1, which is similar to reported for some high-efficiency nanofiber filters. In addition, it also retains BC particles present in air, which was about 90 % for 375 nm and about 60 % for the 880 nm wavelength. Finally, this research provided information for future designs of indoor air filters and filter media for facial masks with renewable, non-toxic biodegradable, and potential antibacterial characteristics.

Human Health and Economic Costs of Air Pollution in Utah: An Expert Assessment

Air pollution causes more damage to health and economy than previously understood, contributing to approximately one in six deaths globally. However, pollution reduction policies remain controversial even when proven effective and cost negative, partially because of misunderstanding and growing mistrust in science. We used an expert assessment to bridge these research–policy divides in the State of Utah, USA, combining quantitative estimates from 23 local researchers and specialists on the human health and economic costs of air pollution. Experts estimated that air pollution in Utah causes 2480 to 8000 premature deaths annually (90% confidence interval) and decreases the median life expectancy by 1.1 to 3.6 years. Economic costs of air pollution in Utah totaled $0.75 to $3.3 billion annually, up to 1.7% of the state’s gross domestic product. Though these results were generally in line with available estimates from downscaled national studies, they were met with surprise in the state legislature, where there had been an almost complete absence of quantitative health and economic cost estimates. We discuss the legislative and personal responses of Utah policy makers to these results and present a framework for increasing the assimilation of data into decision making via regional expert assessment. In conclusion, combining quantitative assessments from local experts is a responsive and cost-effective tool to increase trust and information uptake during time-sensitive policy windows.

Complex Characterization of Fine Fraction and Source Contribution to PM2.5 Mass at an Urban Area in Central Europe

It is well documented that Southern Poland is one of the most polluted areas in Europe due to the highest airborne concentrations of particulate matter (PM). Concentrations of fine particles are especially high in winter. Apart from detailed number concentrations, it is essential to accurately identify and quantify specific particulate pollution sources. Only a few Polish research centers are involved in such experiments—among them is Krakow research group. For the most part, research focuses on collecting 24-h average samples from stationary PM samplers at ambient monitoring sites and quantifying the specific elements and chemical constituents in PM. This approach includes modeling methods that can use the variability in physical and chemical PM characteristics as an input dataset to identify possible sources of the particles. The objective of this paper is to provide research results based on data collected from June 2018 to May 2019 from a single monitoring station at a central urban site. Careful comparison of data obtained prior to a 2019 law prohibiting solid fuel burning in the city of Krakow with data (2019–2020) when a regulation went into effect should indicate progress by noting lower PM levels. This work has shown that the method applied and Krakow results might be of interest to the broader community in regions of high PM concentration.

Wildfire Smoke Transport and Air Quality Impacts in Different Regions of China

The air quality and human health impacts of wildfires depend on fire, meteorology, and demography. These properties vary substantially from one region to another in China. This study compared smoke from more than a dozen wildfires in Northeast, North, and Southwest China to understand the regional differences in smoke transport and the air quality and human health impacts. Smoke was simulated using the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) with fire emissions obtained from the Global Fire Emission Database (GFED). Although the simulated PM2.5 concentrations reached unhealthy or more severe levels at regional scale for some largest fires in Northeast China, smoke from only one fire was transported to densely populated areas (population density greater than 100 people/km2). In comparison, the PM2.5 concentrations reached unhealthy level in local densely populated areas for a few fires in North and Southwest China, though they were very low at regional scale. Thus, individual fires with very large sizes in Northeast China had a large amount of emissions but with a small chance to affect air quality in densely populated areas, while those in North and Southwest China had a small amount of emissions but with a certain chance to affect local densely populated areas. The results suggest that the fire and air quality management should focus on the regional air quality and human health impacts of very large fires under southward/southeastward winds toward densely populated areas in Northeast China and local air pollution near fire sites in North and Southwest China.

Particulate Matter 2.5 Induced Developmental Cardiotoxicity in Chicken Embryo and Hatchling

Particulate matter poses health risk to developing organisms. To investigate particulate matters with a diameter smaller than 2.5 um (PM2.5)-induced developmental cardiotoxicity, fertile chicken eggs were exposed to PM2.5 via air cell injection at doses of 0.05, 0.2, 0.5, 2, and 5 mg/egg kg. Morphological changes in the embryonic day four (ED4) and hatchling hearts were assessed with histological techniques. Heart rates of hatchling chickens were measured with electrocardiography. The protein expression levels of nuclear factor kappa-light-chain-enhancer of activated B cells p65 (NF-kb p65), inducible nitric oxide synthase (iNOS), and matrix metallopeptidase 9 (MMP9) were assessed with immunohistochemistry or western blotting in hatchling hearts. PM2.5 exposure elevated areas of heart in ED4 embryo, increased heart rate, and thickened right ventricular wall thickness in hatchling chickens. Immunohistochemistry revealed enhanced NF-kb p65 expression in hatchling hearts. Western blotting results indicated that both iNOS and MMP9 expression were enhanced by lower doses of PM2.5 exposure (0.2 and 0.5 mg/kg) but not 2 mg/kg. In summary, developmental exposure to PM2.5 induced developmental cardiotoxicity in chicken embryo and hatchling chickens, which is associated with NF-kb p65, iNOS, and MMP9.

Chemical characterization of fine particles (PM2.5) at a coastal site in the South Western Mediterranean during the ChArMex experiment

As part of the ChArMEx project (Chemistry-Aerosol Mediterranean Experiment, http://charmex.lsce.ipsl.fr), one year of continuous filter sampling was conducted from August 2012 to August 2013 at a rural (coastal) site in Algeria aiming to better document fine aerosol seasonal variability and chemical composition in the Southern part of the Mediterranean. Over 350 filters have been collected, weighted, and analyzed for the main ions and organic and elemental carbon. The obtained mass concentrations varied between 2.5 and 50.6 μg/m³ for PM_2.5. The annual modulations of PM_2.5 showed higher concentrations in the end summer 2012 and the early summer 2013 (28.50 μg/m³ in August 2012, 20.23 μg/m³ in September 2012, 20.19 μg/m³ in July 2013, and 17.88 μg/m³in August 2013). The particulate organic matter (POM) presented the greatest contribution (50%), followed by the secondary inorganic aerosols (SIA, 27%). The average organic carbon OC concentrations ranged from 1.66 to 6.05 μgC/m³. The average elemental carbon EC concentrations ranged from 0.92 to 3.49 μgC/m³ and contributed 7% of the PM_2.5 mass to Bou-Ismail. The average value of the OC /EC ratio was close to 5.1 in Bou-Ismail, and was close to that found in Finokalia 4 (Greece 2004, 2006) but was lower than that of Montseny 11 (Spain 2002-2007) Western Mediterranean Basin (WMB). The concentrations of water-soluble organic carbon WSOC in the PM_2.5 ranging from 0.66 to 3.70 μg/m³ recorded the minimum level in March 2013, and the maximum level in August 2012, with an average of 2.02 μg/m³.

Health and economic consequences of applying the United States' PM2.5 automobile emission standards to other nations: a case study of France and Italy

OBJECTIVES

The US has among the world's strictest automobile emission standards, but it is now loosening them. It is unclear where a nation should draw the line between the associated cost burden imposed by regulations and the broader societal benefits associated with having cleaner air. Our study examines the health benefits and cost-effectiveness of introducing stricter vehicle emission standards in France and Italy.

STUDY DESIGN

Quasi-experimental study.

METHODS

We used cost-effectiveness modeling to measure the incremental quality-adjusted life years (QALYs) and cost (Euros) of adopting more stringent US vehicle emission standards for PM2.5 in France and Italy.

RESULTS

Adopting Obama era US vehicle emission standards would likely save money and lives for both the French and Italian populations. In France, adopting US emission standards would save €1000 and increase QALYs by 0.04 per capita. In Italy, the stricter standards would save €3000 and increase QALYs by 0.31. The results remain robust in both the sensitivity analysis and probabilistic Monte Carlo simulation model.

CONCLUSIONS

Adopting more stringent emission standards in France and Italy would save money and lives.

Alzheimer disease starts in childhood in polluted Metropolitan Mexico City. A major health crisis in progress

Exposures to fine particulate matter (PM_2.5) and ozone (O₃) above USEPA standards are associated with Alzheimer's disease (AD) risk. Metropolitan Mexico City (MMC) youth have life time exposures to PM_2.5 and O₃ above standards. We focused on MMC residents ≤30 years and reviewed 134 consecutive autopsies of subjects age 20.03 ± 6.38 y (range 11 months to 30 y), the staging of Htau and ß amyloid, the lifetime cumulative PM_2.5 (CPM _2.5) and the impact of the Apolipoprotein E (APOE) 4 allele, the most prevalent genetic risk for AD. We also reviewed the results of the Montreal Cognitive Assessment (MoCA) and the brainstem auditory evoked potentials (BAEPs) in clinically healthy young cohorts. Mobile sources, particularly from non-regulated diesel vehicles dominate the MMC pollutant emissions exposing the population to PM_2.5 concentrations above WHO and EPA standards. Iron-rich,magnetic, highly oxidative, combustion and friction-derived nanoparticles (CFDNPs) are measured in the brain of every MMC resident. Progressive development of Alzheimer starts in childhood and in 99.25% of 134 consecutive autopsies ≤30 years we can stage the disease and its progression; 66% of ≤30 years urbanites have cognitive impairment and involvement of the brainstem is reflected by auditory central dysfunction in every subject studied. The average age for dementia using MoCA is 20.6 ± 3.4 y. APOE4 vs 3 carriers have 1.26 higher odds of committing suicide. PM_2.5 and CFDNPs play a key role in the development of neuroinflammation and neurodegeneration in young urbanites. A serious health crisis is in progress with social, educational, judicial, economic and overall negative health impact for 25 million residents. Understanding the neural circuitry associated with the earliest cognitive and behavioral manifestations of AD is needed. Air pollution control should be prioritised-including the regulation of diesel vehicles- and the first two decades of life ought to be targeted for neuroprotective interventions. Defining paediatric environmental, nutritional, metabolic and genetic risk factor interactions is a multidisciplinary task of paramount importance to prevent Alzheimer's disease. Current and future generations are at risk.

Optimal Inversion of Conversion Parameters from Satellite AOD to Ground Aerosol Extinction Coefficient Using Automatic Differentiation

Satellite aerosol optical depth (AOD) plays an important role for high spatiotemporal-resolution estimation of fine particulate matter with diameters ≤2.5 μm (PM2.5). However, the MODIS sensors aboard the Terra and Aqua satellites mainly measure column (integrated) AOD using the aerosol (extinction) coefficient integrated over all altitudes in the atmosphere, and column AOD is less related to PM2.5 than low-level or ground-based aerosol (extinction) coefficient (GAC). With recent development of automatic differentiation (AD) that has been widely applied in deep learning, a method using AD to find optimal solution of conversion parameters from column AOD to the simulated GAC is presented. Based on the computational graph, AD has considerably improved the efficiency in applying gradient descent to find the optimal solution for complex problems involving multiple parameters and spatiotemporal factors. In a case study of the Jing-Jin-Ji region of China for the estimation of PM2.5 in 2015 using the Multiangle Implementation of Atmospheric Correction AOD, the optimal solution of the conversion parameters was obtained using AD and the loss function of mean square error. This solution fairly modestly improved the Pearson’s correlation between simulated GAC and PM2.5 up to 0.58 (test R2: 0.33), in comparison with three existing methods. In the downstream validation, the simulated GACs were used to reliably estimate PM2.5, considerably improving test R2 up to 0.90 and achieving consistent match for GAC and PM2.5 in their spatial distribution and seasonal variations. With the availability of the AD tool, the proposed method can be generalized to the inversion of other similar conversion parameters in remote sensing.

Exposure to air pollutants and heat stress among resource-poor women entrepreneurs in small-scale cassava processing

Exposure to air pollutants and heat stress from traditional cooking fires is the leading cause of mortality and morbidity in low- and middle-income countries globally and have an adverse effect on the environment. According to the World Health Organization, 3.8 million people die annually prematurely from illness related to household air pollution. Families living in poverty are at the highest risk, especially women and children. In this study, exposure to particulate matter (PM_2.5 and PM₁₀), carbon monoxide (CO) and nitrogen dioxide (NO₂) was measured among resource-poor women cassava processors. The test locations were chosen in the peri-urban settlements of Abeokuta in the Ogun State of Nigeria, where household women entrepreneurs roast garri (granulated cassava) for sale in the local market. The measurements were taken for two types of stoves which are generally existing in the study location. First, a rectangular stove (RS) with two operators and, second, a circular stove (CS) with one operator; both stoves used wood as fuel. The emissions were compared with a modern mechanical liquefied petroleum gas burner-based garri roaster (GS). Hours spent per day in front of garri stoves ranged from 6 to 12 h for both stoves, with a frequency of 1 to 3 days of operation per week. It was found that CS operators were spending significantly more time in producing garri, which is due to the low capacity of the CS. The average PM_2.5 concentrations for RS and CS were 381 and 273 μg/m³, respectively, estimated to be 21 and 41 μg/m³ on an annual mean level basis. Similarly, for PM₁₀, the mean concentration levels were 1580 and 594 μg/m³ for RS and CS, respectively. The annual mean levels for PM₁₀ were about 89 μg/m³ for both types of stoves. CO exposure during garri processing was up to five times higher than the recommended concentrations with a 4-h mean of 48 and 50 mg/m³ for RS and CS, respectively. NO₂ levels were very low, ~ 0 ppm. This investigative research concluded that wood-fired small-scale garri producers in Nigeria are exposed to very unhealthy levels of PM, CO and thermal stress. The concentration levels of both PM and CO were exceeding the global as well as Nigerian ambient air quality standard regulations. Along with air pollution, thermal stress was a significant issue, which is known to exacerbate the negative effect of air pollution on the human body.

Air Pollution and Cardiovascular Disease: JACC State-of-the-Art Review

Fine particulate matter <2.5 μm (PM_2.5) air pollution is the most important environmental risk factor contributing to global cardiovascular (CV) mortality and disability. Short-term elevations in PM_2.5 increase the relative risk of acute CV events by 1% to 3% within a few days. Longer-term exposures over several years increase this risk by a larger magnitude (∼10%), which is partially attributable to the development of cardiometabolic conditions (e.g., hypertension and diabetes mellitus). As such, ambient PM_2.5 poses a major threat to global public health. In this review, the authors provide an overview of air pollution and health, including assessment of exposure, impact on CV outcomes, mechanistic underpinnings, and impact of air pollution reduction strategies to mitigate CV risk. The review concludes with future challenges, including the inextricable link between air pollution and climate change, and calls for large-scale trials to allow the promulgation of formal evidence-based recommendations to lower air pollution-induced health risks.

Application of the Orthogonal Polynomial Fitting Method in Estimating PM2.5 Concentrations in Central and Southern Regions of China

Sufficient and accurate air pollutant data are essential to analyze and control air contamination problems. An orthogonal polynomial fitting (OPF) method using Chebyshev basis functions is introduced to produce spatial distributions of fine particle (PM_2.5) concentrations in central and southern regions of China. Idealized twin experiments (IE1 and IE2) are designed to validate the feasibility of the OPF method. IE1 is designed in accordance with the most common distribution of PM_2.5 concentrations in China, whereas IE2 represents a common distribution in spring and autumn. In both idealized experiments, prescribed distributions are successfully estimated by the OPF method with smaller errors than kriging or Cressman interpolations. In practical experiments, cross-validation is employed to assess the interpolation results. Distributions of PM_2.5 concentrations are well improved when OPF is applied. This suggests that errors decrease when the fitting order increases and arrives at the minimum when both orders reach 6. Results calculated by the OPF method are more accurate than kriging and Cressman interpolations if appropriate fitting orders are selected in practical experiments.

Air pollution in India and related adverse respiratory health effects: past, present, and future directions

PURPOSE OF REVIEW

The review describes current status of air pollution in India, summarizes recent research on adverse health effects of ambient and household air pollution, and outlines the ongoing efforts and future actions required to improve air quality and reduce morbidity and mortality because of air pollution in India.

RECENT FINDINGS

Global burden of disease data analysis reveals more than one million premature deaths attributable to ambient air pollution in 2015 in India. More than one million additional deaths can be attributed to household air pollution. Particulate matter with diameter 2.5 μm or less has been causatively linked with most premature deaths. Acute respiratory tract infections, asthma, chronic obstructive pulmonary disease, exacerbations of preexisting obstructive airway disease and lung cancer are proven adverse respiratory effects of air pollution. Targeting air quality standards laid by WHO can significantly reduce morbidity and mortality because of air pollution in India.

SUMMARY

India is currently exposed to high levels of ambient and household air pollutants. Respiratory adverse effects of air pollution are significant contributors to morbidity and premature mortality in India. Substantial efforts are being made at legislative, administrative, and community levels to improve air quality. However, much more needs to be done to change the 'status quo' and attain the target air quality standards. VIDEO ABSTRACT: http://links.lww.com/COPM/A24.

Air pollution and female fertility: a systematic review of literature

Air pollution is a cause of concern for human health. For instance, it is associated with an increased risk for cancer, cardiovascular and respiratory disorders. In vitro and in vivo studies suggested that air pollutants could act as endocrine disruptors, promote oxidative stress and exert genotoxic effect. Whether air pollution affects female infertility is under debate. The aim of the present study was to conduct a systematic review of studies that evaluated the impact of air pollution on female infertility. We systematically searched the MEDLINE (PubMed) and SCOPUS databases to identify all relevant studies published before October 2017. No time or language restrictions were adopted, and queries were limited to human studies. We also hand-searched the reference lists of relevant studies to ensure we did not miss pertinent studies. The risk of bias and quality assessment of the studies identified were performed using the Newcastle-Ottawa Scale. Primary outcomes were conception rate after spontaneous intercourse and live birth rate after in vitro fertilization (IVF) procedures. Secondary outcomes were first trimester miscarriage, stillbirths, infertility, number of oocytes and embryo retrieved. Eleven articles were included in the analysis. We found that in the IVF population, nitrogen dioxide and ozone were associated with a reduced live birth rate while particulate matter of 10 mm was associated with increased miscarriage. Furthermore, in the general population, particulate matter of 2.5 mm and between 2.5 and 10 mm were associated with reduced fecundability, whereas sulfur dioxide_, carbon monoxide and nitrogen dioxide might promote miscarriage and stillbirths. The main limitation of our findigns resides in the fact that the desegn of studies included are observational and retrospective. Furthermore, there was a wide heterogenity among studies. Although larger trials are required before drawing definitive conclusions, it seems that air pollution could represent a matter of concern for female infertility.

Modernizing the Bradford Hill criteria for assessing causal relationships in observational data

Perhaps no other topic in risk analysis is more difficult, more controversial, or more important to risk management policy analysts and decision-makers than how to draw valid, correctly qualified causal conclusions from observational data. Statistical methods can readily quantify associations between observed variables using measures such as relative risk (RR) ratios, odds ratios (OR), slope coefficients for exposure or treatment variables in regression models, and quantities derived from these measures. Textbooks of epidemiology explain how to calculate population attributable fractions, attributable risks, burden-of-disease estimates, and probabilities of causation from relative risk (RR) ratios. Despite their suggestive names, these association-based measures have no necessary connection to causation if the associations on which they are based arise from bias, confounding, p-hacking, coincident historical trends, or other noncausal sources. But policy analysts and decision makers need something more: trustworthy predictions - and, later, evaluations - of the changes in outcomes caused by changes in policy variables. This concept of manipulative causation differs from the more familiar concepts of associational and attributive causation most widely used in epidemiology. Drawing on modern literature on causal discovery and inference principles and algorithms for drawing limited but useful causal conclusions from observational data, we propose seven criteria for assessing consistency of data with a manipulative causal exposure-response relationship - mutual information, directed dependence, internal and external consistency, coherent causal explanation of biological plausibility, causal mediation confirmation, and refutation of non-causal explanations - and discuss to what extent it is now possible to automate discovery of manipulative causal dependencies and quantification of causal effects from observational data. We compare our proposed principles for causal discovery and inference to the traditional Bradford Hill considerations from 1965. Understanding how old and new principles are related can clarify and enrich both.

The burden of disease attributable to ambient PM2.5-bound PAHs exposure in Nagpur, India

Exposure to PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) can elicit several types of cancer and non-cancer effects. Previous studies reported substantial burdens of PAH-induced lung cancer, but the burdens of other cancer types and non-cancer effects remain unknown. Thus, we estimate the cancer and non-cancer burden of disease, in disability-adjusted life years (DALYs), attributable to ambient PM_2.5-bound PAHs exposure in Nagpur district, India, using risk-based approach. We measured thirteen PAHs in airborne PM_2.5 sampled from nine sites covering urban, peri-urban and rural areas, from February 2013 to June 2014. We converted PAHs concentrations to benzo[a]pyrene equivalence (B[a]P_eq) for cancer and non-cancer effects using relative potency factors, and relative toxicity factors derived from quantitative structure-activity relationships, respectively. We calculated time-weighted exposure to B[a]P_eq, averaged over 30 years, and adjusted for early-life susceptibility to cancer. We estimated the DALYs/year using B[a]P_eq exposure levels, published toxicity data, and severity of the diseases from Global Burden of Disease 2016 database. The annual average concentration of total PM_2.5-bound PAHs was 458 ± 246 ng/m³ and resulted in 49,500 DALYs/year (0.011 DALYs/person/year). The PAH-related DALYs followed this order: developmental (mostly cardiovascular) impairments (55.1%) > cancer (26.5%) or lung cancer (23.1%) > immunological impairments (18.0%) > reproductive abnormalities (0.4%).

The effects of facemasks on airway inflammation and endothelial dysfunction in healthy young adults: a double-blind, randomized, controlled crossover study

Background

Facemasks are increasingly worn during air pollution episodes in China, but their protective effects are poorly understood. We aimed to evaluate the filtration efficiencies of N95 facemasks and the cardiopulmonary benefits associated with wearing facemasks during episodes of pollution.

Results

We measured the filtration efficiencies of particles in ambient air of six types of N95 facemasks with a manikin headform. The most effective one was used in a double-blind, randomized, controlled crossover study, involving 15 healthy young adults, conducted during 2 days of severe pollution in Beijing, China. Subjects were asked to walk along a busy-traffic road for 2 h wearing authentic or sham N95 facemasks. Clinical tests were performed four times to determine changes in the levels of biomarkers of airway inflammation, endothelial dysfunction, and oxidative stress within 24 h after exposure.

The facemasks removed 48–75% of number concentrations of ambient air particles between 5.6 and 560 nm in diameter. After adjustments for multiple comparison, the exhaled nitric oxide level and the levels of interleukin-1α, interleukin-1β, and interleukin-6 in exhaled breath condensate increased significantly in all subjects; however, the increases in those wearing authentic facemasks were statistically significantly lower than in the sham group. No significant between-group difference was evident in the urinary creatinine-corrected malondialdehyde level. In arterial stiffness indicators, the ejection duration of subjects wearing authentic facemasks was higher after exposure compared to the sham group; no significant between-group difference was found in augmentation pressure or the augmentation index.

Conclusions

In young healthy adults, N95 facemasks partially reduced acute particle-associated airway inflammation, but neither systemic oxidative stress nor endothelial dysfunction improved significantly. The clinical significance of these findings long-term remains to be determined.

Trial registration

The trial registration number (TRN) for this study is ChiCTR1800016099, which was retrospectively registered on May 11, 2018.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0266-0) contains supplementary material, which is available to authorized users.

Independent and Joint Contributions of Fine Particulate Matter Exposure and Population Vulnerability to Mortality in the Detroit Metropolitan Area

Fine particulate matter is associated with adverse health outcomes. Exposure to fine particulate matter may disproportionately affect urban communities with larger numbers of vulnerable residents. We used multilevel logistic regression models to estimate the joint effects of fine particulate matter (PM_2.5) and population vulnerabilities on cardiopulmonary mortality (CPM). We estimated the health benefits of reductions in PM_2.5 across census tracts in the Detroit metropolitan area with varying levels of population vulnerability, using cluster-specific odds ratios scaled to reflect PM_2.5-attributable cardiopulmonary risk. PM_2.5 and population vulnerability were independently associated with odds of CPM. Odds of CPM and the number of deaths attributable to PM_2.5 were greatest in census tracts with both high PM_2.5 exposures and population vulnerability. Reducing PM_2.5 in census tracts with high PM_2.5 would lead to an estimated 18% annual reduction in PM_2.5-attributable CPM. Between 78–79% of those reductions in CPM would occur within census tracts with high population vulnerabilities. These health benefits of reductions in PM_2.5 occurred at levels below current U.S. reference concentrations. Focusing efforts to reduce PM_2.5 in the Detroit metropolitan area in census tracts with currently high levels would also lead to greater benefits for residents of census tracts with high population vulnerabilities.

The gains in life expectancy by ambient PM2.5 pollution reductions in localities in Nigeria

Global burden of disease estimates reveal that people in Nigeria are living shorter lifespan than the regional or global average life expectancy. Ambient air pollution is a top risk factor responsible for the reduced longevity. But, the magnitude of the loss or the gains in longevity accruing from the pollution reductions, which are capable of driving mitigation interventions in Nigeria, remain unknown. Thus, we estimate the loss, and the gains in longevity resulting from ambient PM_2.5 pollution reductions at the local sub-national level using life table approach. Surface average PM_2.5 concentration datasets covering Nigeria with spatial resolution of ∼1 km were obtained from the global gridded concentration fields, and combined with ∼1 km gridded population of the world (GPWv4), and global administrative unit layers (GAUL) for territorial boundaries classification. We estimate the loss or gains in longevity using population-weighted average pollution level and baseline mortality data for cardiopulmonary disease and lung cancer in adults ≥25 years and for respiratory infection in children under 5. As at 2015, there are six "highly polluted", thirty "polluted" and one "moderately polluted" States in Nigeria. People residing in these States lose ∼3.8-4.0, 3.0-3.6 and 2.7 years of life expectancy, respectively, due to the pollution exposure. But, assuming interventions achieve global air quality guideline of 10 μg/m³, longevity would increase by 2.6-2.9, 1.9-2.5 and 1.6 years for people in the State-categories, respectively. The longevity gains are indeed high, but to achieve them, mitigation interventions should target emission sources having the highest population exposures.

Estimating health and economic benefits of reductions in air pollution from agriculture

Agricultural ammonia emissions strongly contribute to fine particulate air pollution (PM_2.5) with significant impacts on human health, contributing to mortality. We used model calculated emission scenarios to examine the health and economic benefits accrued by reducing agricultural emissions. We applied the "value of statistical life" metric to monetize the associated health outcomes. Our analysis indicates that a 50% reduction in agricultural emissions could prevent >200 thousand deaths per year in the 59 countries included in our study, notably in Europe, Russia, Turkey, the US, Canada and China, accompanied with economic benefits of many billions US$. In the European Union (EU) mortality could be reduced by 18% with an annual economic benefit of 89 billion US$. A theoretical complete phase-out of agricultural emissions could lead to a reduction in PM_2.5 related mortality of >50% plus associated economic costs in 42 out of the 59 countries studied. Within the EU, 140 thousand deaths could be prevented per year with an associated economic benefit of about 407billionUS$/year. A cost-benefit assessment of ammonia emission abatement options for the EU indicates that the reduction of agricultural emissions generates net financial and social benefits. The monetization of the health benefits of air pollution abatement policies and the costs of implementation can help devise cost-effective air quality management strategies.

A Review of Recent Advances in Research on PM2.5 in China

PM_2.5 pollution has become a severe problem in China due to rapid industrialization and high energy consumption. It can cause increases in the incidence of various respiratory diseases and resident mortality rates, as well as increase in the energy consumption in heating, ventilation, and air conditioning (HVAC) systems due to the need for air purification. This paper reviews and studies the sources of indoor and outdoor PM_2.5, the impact of PM_2.5 pollution on atmospheric visibility, occupational health, and occupants’ behaviors. This paper also presents current pollution status in China, the relationship between indoor and outdoor PM_2.5, and control of indoor PM_2.5, and finally presents analysis and suggestions for future research.

Residential energy use emissions dominate health impacts from exposure to ambient particulate matter in India

Exposure to ambient fine particulate matter (PM_2.5) is a leading contributor to diseases in India. Previous studies analysing emission source attributions were restricted by coarse model resolution and limited PM_2.5 observations. We use a regional model informed by new observations to make the first high-resolution study of the sector-specific disease burden from ambient PM_2.5 exposure in India. Observed annual mean PM_2.5 concentrations exceed 100 μg m⁻³ and are well simulated by the model. We calculate that the emissions from residential energy use dominate (52%) population-weighted annual mean PM_2.5 concentrations, and are attributed to 511,000 (95UI: 340,000–697,000) premature mortalities annually. However, removing residential energy use emissions would avert only 256,000 (95UI: 162,000–340,000), due to the non-linear exposure–response relationship causing health effects to saturate at high PM_2.5 concentrations. Consequently, large reductions in emissions will be required to reduce the health burden from ambient PM_2.5 exposure in India.

Exposure to ambient particulate matter is a key contributor to disease in India and source attribution is vital for pollution control. Here the authors use a high-resolution regional model to show residential emissions dominate particulate matter concentrations and associated premature mortality.

Long-term trends in the ambient PM2.5- and O3-related mortality burdens in the United States under emission reductions from 1990 to 2010

Concentrations of both fine particulate matter (PM2.5) and ozone (O3) in the United States (US) have decreased significantly since 1990, mainly because of air quality regulations. Exposure to these air pollutants is associated with premature death. Here we quantify the annual mortality burdens from PM2.5 and O3 in the US from 1990 to 2010, estimate trends and inter-annual variability, and evaluate the contributions to those trends from changes in pollutant concentrations, population, and baseline mortality rates. We use a fine-resolution (36 km) self-consistent 21-year simulation of air pollutant concentrations in the US from 1990 to 2010, a health impact function, and annual county-level population and baseline mortality rate estimates. From 1990 to 2010, the modeled population-weighted annual PM2.5 decreased by 39 %, and summertime (April to September) 1 h average daily maximum O3 decreased by 9 % from 1990 to 2010. The PM2.5-related mortality burden from ischemic heart disease, chronic obstructive pulmonary disease, lung cancer, and stroke steadily decreased by 54% from 123 700 deaths year-1 (95% confidence interval, 70 800-178 100) in 1990 to 58 600 deaths year-1 (24 900-98 500) in 2010. The PM2.5-related mortality burden would have decreased by only 24% from 1990 to 2010 if the PM2.5 concentrations had stayed at the 1990 level, due to decreases in baseline mortality rates for major diseases affected by PM2.5. The mortality burden associated with O3 from chronic respiratory disease increased by 13% from 10 900 deaths year-1 (3700-17 500) in 1990 to 12 300 deaths year-1 (4100-19 800) in 2010, mainly caused by increases in the baseline mortality rates and population, despite decreases in O3 concentration. The O3-related mortality burden would have increased by 55% from 1990 to 2010 if the O3 concentrations had stayed at the 1990 level. The detrended annual O3 mortality burden has larger inter-annual variability (coefficient of variation of 12%) than the PM2.5-related burden (4%), mainly from the inter-annual variation of O3 concentration. We conclude that air quality improvements have significantly decreased the mortality burden, avoiding roughly 35 800 (38%) PM2.5-related deaths and 4600 (27%) O3-related deaths in 2010, compared to the case if air quality had stayed at 1990 levels (at 2010 baseline mortality rates and population).

Aerosol Health Effects from Molecular to Global Scales

Poor air quality is globally the largest environmental health risk. Epidemiological studies have uncovered clear relationships of gaseous pollutants and particulate matter (PM) with adverse health outcomes, including mortality by cardiovascular and respiratory diseases. Studies of health impacts by aerosols are highly multidisciplinary with a broad range of scales in space and time. We assess recent advances and future challenges regarding aerosol effects on health from molecular to global scales through epidemiological studies, field measurements, health-related properties of PM, and multiphase interactions of oxidants and PM upon respiratory deposition. Global modeling combined with epidemiological exposure-response functions indicates that ambient air pollution causes more than four million premature deaths per year. Epidemiological studies usually refer to PM mass concentrations, but some health effects may relate to specific constituents such as bioaerosols, polycyclic aromatic compounds, and transition metals. Various analytical techniques and cellular and molecular assays are applied to assess the redox activity of PM and the formation of reactive oxygen species. Multiphase chemical interactions of lung antioxidants with atmospheric pollutants are crucial to the mechanistic and molecular understanding of oxidative stress upon respiratory deposition. The role of distinct PM components in health impacts and mortality needs to be clarified by integrated research on various spatiotemporal scales for better evaluation and mitigation of aerosol effects on public health in the Anthropocene.

Outdoor Ambient Air Pollution and Neurodegenerative Diseases: the Neuroinflammation Hypothesis

PURPOSE OF REVIEW

Accumulating research indicates that ambient outdoor air pollution impacts the brain and may affect neurodegenerative diseases, yet the potential underlying mechanisms are poorly understood.

RECENT FINDINGS

The neuroinflammation hypothesis holds that elevation of cytokines and reactive oxygen species in the brain mediates the deleterious effects of urban air pollution on the central nervous system (CNS). Studies in human and animal research document that neuroinflammation occurs in response to several inhaled pollutants. Microglia are a prominent source of cytokines and reactive oxygen species in the brain, implicated in the progressive neuron damage in diverse neurodegenerative diseases, and activated by inhaled components of urban air pollution through both direct and indirect pathways. The MAC1-NOX2 pathway has been identified as a mechanism through which microglia respond to different forms of air pollution, suggesting a potential common deleterious pathway. Multiple direct and indirect pathways in response to air pollution exposure likely interact in concert to exert CNS effects.