Concentration-response Functions Research Articles

Estimation of hospital visits for respiratory diseases attributable to PM10 from vegetation fire smoke and health impacts of regulatory intervention in Upper Northern Thailand

The air quality in Upper Northern Thailand (UNT) deteriorates during seasonal vegetation fire events, causing adverse effects especially on respiratory health outcomes. This study aimed to quantitatively estimate respiratory morbidity from vegetation fire smoke exposure, and to assess the impact of a burning ban enforced in 2016 on morbidity burden in UNT. We computed daily population exposure to fire-originated PM10 and estimated its health burden during a 5-year period from 2014 to 2018 using daily fire-originated PM10 concentration and the concentration–response function for short-term exposure to PM10 from vegetation fire smoke and respiratory morbidity. In subgroups classified as children and older adults, the health burden of respiratory morbidity was estimated using specific effect coefficients from previous studies conducted in UNT. Finally, we compared the health burden of respiratory morbidity before and after burning ban enforcement. Approximately 130,000 hospital visits for respiratory diseases were estimated to be attributable to fire-originated PM10 in UNT from 2014 to 2018. This estimation accounted for 1.3% of total hospital visits for respiratory diseases during the 5-year period, and 20% of those during burning events. Age-specific estimates revealed a larger impact of PM10 in the older adult group. The number of hospital visits for respiratory diseases attributable to fire-originated PM10 decreased from 1.8% to 0.5% after the burning ban policy was implemented in the area. Our findings suggest that PM10 released from vegetation fires is a health burden in UNT. The prohibition of the burning using regulatory measure had a positive impact on respiratory morbidity in this area.

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 (PM2.5). However, the policy effectiveness of ACP and co-benefits of carbon mitigation measures to environment and health are still largely unknown. Using satellite-based PM2.5 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 PM2.5 exposure, and quantitatively estimated the policy benefits of ACP and carbon mitigation measures. We found the annual PM2.5 concentrations in China decreased by 33.65% (13.41μgm-3) from 2014 to 2020, accompanied by a decrease in PM2.5-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 PM2.5 in mainland China in 2020. Among all ACP measures, clean production (contributed 55.98% and 51.14% to decrease in PM2.5 and premature deaths attributable to PM2.5) and energy consumption control (contributed 32.58% and 29.54% to decrease in PM2.5 and premature deaths attributable to PM2.5) 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 PM2.5 has become one of the major drivers for PM2.5 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.

Health and economic impacts of ambient air particulate matter (PM2.5) in Karaj city from 2012 to 2019 using BenMAP-CE.

The present study aims to estimate the effects of PM2.5 on the health and economy of Karaj city from 2012 to 2019. In this study, mortality attributed to long-term exposure to PM2.5 and its spatial distribution in Karaj over the 2012-2019 period were estimated using the Global Exposure Mortality Model (GEMM) concentration-response function and BenMAP software. PM2.5 hourly concentration data of air quality monitoring stations were used to estimate PM2.5 for the whole city of Karaj. The economic effects of this pollutant were also assessed using the value of statistical life (VSL) method. The results showed that the annual average PM2.5 concentration during the studied time increased and was higher than the air quality guideline levels recommended by the World Health Organization. Also, the annual number of deaths attributed to PM2.5 in adults (older than 25years) was estimated to be about 1200. The highest to lowest proportions of PM2.5-related deaths were non-accidental mortality, ischemic heart attack, stroke, acute respiratory tract infection, chronic obstructive pulmonary disease (COPD), and lung cancer, in the order of their appearance. The results showed that the economic loss attributed to this pollutant was estimated at 380 to 504 million USD per year. Due to the effects of PM2.5 on health and the economy in this city, we suggest conducting special planning to control and reduce the concentration of ambient air particulate matter by improving the public transportation system and updating industrial processes.

How low can you go? Air pollution affects mortality at very low levels.

The World Health Organization (WHO) recently released new guidelines for outdoor fine particulate air pollution (PM2.5) recommending an annual average concentration of 5 μg/m3. Yet, our understanding of the concentration-response relationship between outdoor PM2.5 and mortality in this range of near-background concentrations remains incomplete. To address this uncertainty, we conducted a population-based cohort study of 7.1 million adults in one of the world’s lowest exposure environments. Our findings reveal a supralinear concentration-response relationship between outdoor PM2.5 and mortality at very low (<5 μg/m3) concentrations. Our updated global concentration-response function incorporating this new information suggests an additional 1.5 million deaths globally attributable to outdoor PM2.5 annually compared to previous estimates. The global health benefits of meeting the new WHO guideline for outdoor PM2.5 are greater than previously assumed and indicate a need for continued reductions in outdoor air pollution around the world.

Exports Widen the Regional Inequality of Health Burdens and Economic Benefits in India

Both the ever-complex international and subnational supply chains could relocate health burdens and economic benefits across India, leading to the widening of regional inequality. Here, we simultaneously track the unequal distribution of fine particle matter (PM2.5) pollution, health costs, and value-added embodied in inter- and intranational exports for Indian states in 2015 by integrating a nested multiregional input-output (MRIO) table constructed based on EXIOBASE and an Indian regional MRIO table, Emissions Database for Global Atmospheric Research (EDGAR), the Community Multi-Scale Air Quality (CMAQ) model, and a concentration-response function. The results showed that the annual premature deaths associated with PM2.5 pollution embodied in inter- and intranational exports were 757,356 and 388,003 throughout India, accounting for 39% and 20% of the total premature deaths caused by PM2.5 pollution, respectively. Richer south and west coastal states received around half of the national Gross Domestic Product (GDP) induced by exports with a quarter of the health burden, while poorer central and east states bear approximately 60% of the health burden with less than a quarter of national GDP. Our findings highlight the role of exports in driving the regional inequality of health burdens and economic benefits. Therefore, tailored strategies (e.g., air pollution compensation, advanced technology transfer, and export structure optimization) could be formulated.

Investigating the Regional Concentrations-Response Relations between PM2.5 and daily mortality in Japan

BACKGROUND: The concentration-response (CR) functions of PM2.5 are sensitive to various local factors, such as meteorological conditions, PM sources and components, and population sensitivity to PM. However, the shape of local CR functions remains unclear in many regions in Japan. This research investigates the association between PM2.5 and cause-, age-, and location-specific mortality to identify susceptible subpopulations and regions using a nationwide dataset. METHODS: A two-stage analysis was performed to quantify the associations of PM2.5 with mortality. In the first stage, regional differences in the effects of PM were investigated. A time-series quasi-Poisson model, combined with a distributed lag non-linear model and a flexible functional form of splines, was applied to evaluate the location-specific associations between PM2.5 and mortality. Various covariates were controlled, including weather variables, day of the week, and seasonal and long-term time trends. Stratified analyses were performed by age groups and death cause categories. We used a random-effects meta-analytic model to estimate the pooled cumulative association in the second stage. Potential reasons for the regional heterogeneity of PM2.5 effects were further explored through random-effects meta-regression analyses, separately carried out for multiple variables as meta-predictors. RESULTS: Geographic variations in the concentration of PM2.5 were observed in Japan. An increase in PM2.5 concentration was associated with an increase in excess risk of mortality, and the magnitude of the corresponding associations appeared to vary by region in Japan. CONCLUSIONS: The regional risks of premature mortality from exposure to PM2.5 were investigated. We identified vulnerable regions and susceptible subpopulations. The disparity in the association of mortality risks and PM2.5 was apparent between geographical regions, indicating the importance of developing area-specific strategies and local risk prevention plans that can serve as a basis for policymaking to reduce the corresponding health effects.

Air pollution impacts at very low levels: Shape of the concentration-mortality relationship in a large population-based Canadian cohort

Background Mortality is associated with long-term exposure to fine particulate matter, although the form of these associations remain poorly understood at lower concentrations. We applied novel 1 km satellite-derived estimates of PM2.5 exposure to a population-based cohort of 7.1 million Canadians. Methods Cox proportional hazard ratios (HRs) were estimated for nonaccidental and cause-specific mortality and 10-year moving average exposure in models adjusted for a wide array of individual and contextual covariates. The shape of the concentration–response function was investigated using restricted cubic splines, threshold models and an extension of the Shape Constrained Health Impact Function (eSCHIF). Analyses examined sensitivity to co-pollutants, concentration thresholds and regional variation. Results Each 10-µg/m3 increase in PM2.5 corresponded with a nonaccidental mortality HR of 1.084 (1.073 -1.096). PM2.5 was associated mortality from ischemic heart disease, pneumonia, COPD, diabetes, and cerebrovascular disease, but not with heart failure, lung cancer, or kidney failure mortality. HR predictions steeply increased from the minimum concentration of 2.5 µg/m3 to 4.5 µg/m3, flattened from 4.5 µg/m3 to 8.0 µg/m3, then increased for concentrations above 8.0 µg/m3, a pattern also reflected in threshold and eSCHIF results. When restricting to those with exposures &amp;#x3c;10 µg/m3 shapes indicated positive associations for concentrations &amp;#x3e;9 µg/m3 with indications of adverse effects on mortality at concentrations as low as 2.5 µg/m3. In sensitivity analyses, PM2.5 - mortality associations were only observed in the highest tertile of oxidant gases with shapes varying across airsheds. These differences, were not related to variation in cohort composition or its access to healthcare, suggesting a role of spatially varying pollutant mixtures not sufficiently characterized by PM2.5 mass concentrations. Conclusions In a large Canadian cohort, associations were observed between exposure to PM2.5 with mortality at concentrations as low as 2.5 µg/m3, with no clear evidence of a threshold.

Impact of exposure measurement error in multi-pollutant models: a simulation study in the time-series framework

BACKGROUND AND AIM Exposure measurement error in air pollutants can lead to biased health effect estimates and effect transfer from more poorly to better measured exposures. While some studies have estimated the impact of error in single-exposure models we aimed to quantify the effect of measurement error in multi-pollutant models, specifically in time-series analysis of PM₂.₅, NO₂, and mortality using simulations, under various plausible scenarios for exposure errors. METHODS Measurement error was defined as the difference between ambient concentrations and personal exposure from outdoor sources. Error-free exposures with their consequent health outcome and error-prone exposures of various error types (classical/Berkson/mixture) were generated using information from the literature. Bias was quantified as the relative difference in effect estimates of the error-free and error-prone exposures. RESULTS NO₂ was assumed to be more prone to error than PM₂.₂, based on separate work, and, thus, its mortality effect estimates were more affected by measurement error bias. The observed bias was up to 37% towards the null, when low ratios of the true exposure variance over the error variance were assumed. Higher ratios resulted in smaller, but still substantial health effect underestimation, up to 19% for both pollutants. Significant effect transfer was observed from NO₂ to PM₂.₅ as the general underestimation due to measurement error was worsened for the former and lessened for the latter compared to single-pollutant model estimates. CONCLUSIONS Our results indicated an underestimation of true independent health effects of multiple exposures due to measurement error. Effect transfer showed that less precise measurements for one pollutant yield more bias, while the co-pollutant associations were found closer to the true. Using error parameter information in future epidemiological studies should provide more accurate concentration-response functions for health impact assessment. KEYWORDS Air pollution, Measurement error, Mixture error, Effect transfer, Simulations

Quantifying the multiple environmental, health, and economic benefits from the electrification of the Delhi public transport bus fleet, estimating a district-wise near roadway avoided PM2.5 exposure

This study investigates the co-benefits from the utilization of the battery-electric bus (BEB) fleet in the Delhi public transportation system as a part of the Delhi electric vehicles policy 2020. To this aim, an integrated quantitative assessment framework is developed to estimate the expected environmental, health, and economic co-benefits from replacing the currently existing public bus fleet with the new BEBs in Delhi. First, the model estimates the avoided emissions from deploying the BEB fleet, using a detailed battery energy simulation model, considering the impact of the battery capacity loss on the annual operational time (hours of service) of the BEB. The annual operational time of the BEB is greatly affected by its battery degradation, which results in time lost due to charging the battery. This indicates that the annual passenger-kilometer (PKM) delivered by the BEB is less than the regular bus, under the same traveling condition. Second, considering fine particles (PM2.5) as the most health-harming pollutant, the model calculates the near roadway avoided PM2.5 exposure in the selected traffic zones of 11 major districts of Delhi, using a Gaussian dispersion model. Third, the near roadway avoided PM2.5 exposure is further used in a health impact assessment model, which considers concentration-response functions for several diseases to evaluate the public health benefits from introducing the BEB fleet in Delhi. The research findings indicate that, the utilization of the new BEB fleet leads to a 74.67% reduction in the total pollutant emissions from the existing bus fleet in Delhi. The results of the integrated co-benefits assessment reveal a significant reduction in PM2.5 emissions (44 t/y), leading to avoidance of mortality (1370 cases) and respiratory diseases related hospital admissions (2808 cases), respectively, and an annual savings of about USD 383 million from the avoided mortality and morbidity cases in Delhi.

The health impacts of Indonesian peatland fires

BackgroundIndonesian peatlands have been drained for agricultural development for several decades. This development has made a major contribution to economic development. At the same time, peatland drainage is causing significant air pollution resulting from peatland fires. Peatland fires occur every year, even though their extent is much larger in dry (El Niño) years. We examine the health effects of long-term exposure to fine particles (PM2.5) from all types of peatland fires (including the burning of above and below ground biomass) in Sumatra and Kalimantan, where most peatland fires in Indonesia take place.MethodsWe derive PM2.5 concentrations from satellite imagery calibrated and validated with Indonesian Government data on air pollution, and link increases in these concentrations to peatland fires, as observed in satellite imagery. Subsequently, we apply available epidemiological studies to relate PM2.5 exposure to a range of health outcomes. The model utilizes the age distribution and disease prevalence of the impacted population.ResultsWe find that PM2.5 air pollution from peatland fires, causes, on average, around 33,100 adults and 2900 infants to die prematurely each year from air pollution. In addition, peatland fires cause on average around 4390 additional hospitalizations related to respiratory diseases, 635,000 severe cases of asthma in children, and 8.9 million lost workdays. The majority of these impacts occur in Sumatra because of its much higher population density compared to Kalimantan. A main source of uncertainty is in the Concentration Response Functions (CRFs) that we use, with different CRFs leading to annual premature adult mortality ranging from 19,900 to 64,800 deaths. Currently, the population of both regions is relatively young. With aging of the population over time, vulnerabilities to air pollution and health effects from peatland fires will increase.ConclusionsPeatland fire health impacts provide a further argument to combat fires in peatlands, and gradually transition to peatland management models that do not require drainage and are therefore not prone to fire risks.

Health impacts of PM2.5 originating from residential wood combustion in four nordic cities

BackgroundResidential wood combustion (RWC) is one of the largest sources of fine particles (PM2.5) in the Nordic cities. The current study aims to calculate the related health effects in four studied city areas in Sweden, Finland, Norway, and Denmark.MethodsHealth impact assessment (HIA) was employed as the methodology to quantify the health burden. Firstly, the RWC induced annual average PM2.5 concentrations from local sources were estimated with air pollution dispersion modelling. Secondly, the baseline mortality rates were retrieved from the national health registers. Thirdly, the concentration-response function from a previous epidemiological study was applied. For the health impact calculations, the WHO-developed tool AirQ + was used.ResultsAmongst the studied city areas, the local RWC induced PM2.5 concentration was lowest in the Helsinki Metropolitan Area (population-weighted annual average concentration 0.46 µg m− 3) and highest in Oslo (2.77 µg m− 3). Each year, particulate matter attributed to RWC caused around 19 premature deaths in Umeå (95% CI: 8–29), 85 in the Helsinki Metropolitan Area (95% CI: 35–129), 78 in Copenhagen (95% CI: 33–118), and 232 premature deaths in Oslo (95% CI: 97–346). The average loss of life years per premature death case was approximately ten years; however, in the whole population, this reflects on average a decrease in life expectancy by 0.25 (0.10–0.36) years. In terms of the relative contributions in cities, life expectancy will be decreased by 0.10 (95% CI: 0.05–0.16), 0.18 (95% CI: 0.07–0.28), 0.22 (95% CI: 0.09–0.33) and 0.63 (95% CI: 0.26–0.96) years in the Helsinki Metropolitan Area, Umeå, Copenhagen and Oslo respectively. The number of years of life lost was lowest in Umeå (172, 95% CI: 71–260) and highest in Oslo (2458, 95% CI: 1033–3669).ConclusionsAll four Nordic city areas have a substantial amount of domestic heating, and RWC is one of the most significant sources of PM2.5. This implicates a substantial predicted impact on public health in terms of premature mortality. Thus, several public health measures are needed to reduce the RWC emissions.

Concentration-Response Functions as an Essence of the Results from Lags.

Among various aspects of environmental epidemiology, one is to assess the relationships between ambient air pollution and health outcomes. The goal of this work is to estimate the associations in the form of the parametric concentration–response functions (C-RF). Various forms of the C-RFs are proposed in this short-term health effect study. Emergency department (ED) visits for all respiratory health problems are analyzed as an illustrative example. A case-crossover (CC) technique is applied as a study design. Daily cases are organized as daily counts by the same day of the week in one common month. A conditional Poisson regression is used in the constructed statistical models. Temperature and relative humidity are included in the statistical models in the form of natural splines. Ground-level ozone concentration is considered an exposure. Ozone concentration values are transformed and submitted to the statistical models. The parameters of the transformation are determined by using the goodness of fit criterion. Counts of ED visits are analyzed in relation to a sequence of lagged exposure to ozone. The C-RF shapes are constructed for each individual lag. In a final step, the set of the estimated C-RF shapes is used to create a pooled C-RF shape. The results are positive and statistically significant for nine lagged exposures, from 0 to 8 days. The following relative risks (RR) were estimated from the constructed C-RFs at 30 ppb concentration of ozone: RR = 1.0531 (95% confidence interval: 1.0231, 1.0718), 1.0462 (1.0253, 1.0677), and 1.0387, (1.0240, 1.0531), realizing the CC method, CC method + transformation, and CC method + flexible transformation, respectively. The pooled C-RF shape gives a summary of the associations between ED visits for respiratory conditions and ambient ozone. The estimated shapes indicate lower air health effects than the standard CC methods. Among three considered statistical models, the CC method + flexible transformation is the most appropriate to use according to the goodness of fit criterion.

Design of ultrasensitive gas sensor based on self-assembled Pd-SnO2/rGO porous ternary nanocomposites for ppb-level hydrogen

With the accelerating development of the hydrogen economy, more requirements are put forward for the detection capability of portable hydrogen sensors. Though the fast and accurate detection of hydrogen has been indispensable, there are still some challenges in the detection of extremely low concentrations of hydrogen. In this work, Pd-SnO2/rGO ternary nanocomposites with porous structures were synthesized by a facile template-free hydrothermal method. The effects of each element and its contents on the sensitivity and selectivity to hydrogen were systematically studied. The best hydrogen sensing property was produced by the synergistic effect of the 5.0 Pd-SnO2/rGO ternary nanocomposite, which showed a response of 32.38 toward 200 ppm hydrogen at 360 ℃. Especially, the response of 5.0 Pd-SnO2/rGO to 0.5 ppm (500 ppb) hydrogen reached 2.4, indicating the great potential in the detection of extremely low concentrations of hydrogen. The mechanism of high hydrogen sensitivity and selectivity was elaborated in combination with the analysis of band structure. All the as-prepared sensors exhibit quantitative concentration-response function relationships, favorable reversibility, and long-term stability. This work may provide a feasible strategy for the design of novel H2 sensors with high sensitivity to extremely low concentrations of hydrogen.

Health benefits by attaining the new WHO air quality guideline targets in China: A nationwide analysis

To reduce the high disease burden caused by air pollution, World Health Organization (WHO) issued a new air quality guideline (AQG) on the 22nd September 2021. A timely quantitative assessment of health benefits by meeting these targets is a key measure to advocate and inform national and regional disease control policies. We collected daily major air pollution data in 315 Chinese cities from the 1st January to the 31st December 2019, and the corresponding annual population and mortality rate in the whole population of each city. Then, the mortality benefits were estimated when daily air pollution levels attained WHO's new AQG targets (15 μg/m3 for PM2.5, 25 μg/m3 for NO2 and 100 μg/m3 for O3) in 315 Chinese cities and 31 provinces by using pollutant- and cause-specific concentration-response functions. In total, 134,025 (95%CI: 92,768; 173,029) air pollution-associated non-accidental deaths could be avoided in 315 Chinese cities in 2019 by attaining WHO's new AQG targets, with 43,800 (95%CI: 29,945; 55,616) avoidable deaths from PM2.5, 58,070 (95%CI: 45,333; 70,714) from NO2, and 32,155 (95%CI: 17,490; 46,699) from O3. Cardiovascular diseases and respiratory diseases accounted for 72,698 (95%CI: 46,561; 101,680) and 17,726 (95%CI: 8603; 26,925) avoidable deaths, respectively. Health benefits from reduction in air pollution levels were 99.26 avoided non-accidental deaths per million population at national level, ranging from 12.48 per million in Tibet to 166.26 per million in Hebei. These findings suggest that the compliance with the WHO updated AQG standards would save substantial amount of air pollution-related premature deaths in China. More stringent air pollution control and management measures are urgently warranted to reduce the disease burden from air pollutants in China, particularly for the worsening O3 pollution.

Externality Assessment of Health Damage Caused by PM from PPV of China based on IPA

Health damage caused by pollutants is an important part of environmental externality. Its scientific and accurate evaluation is the basis of environmental policy-making and one of the recent research hotspots. In this paper, the Impact Pathway Approach (IPA) is used to evaluate the externality scale of health damage caused by Particulate Matter (PM) emitted by PPV (Private Passenger Vehicle) of China. Let the public, especially PPV owners, realize that the use of PPV has great health damage to others. Only by making active changes from themselves can reduce the negative externality. The core links of the IPA framework is the Concentration Response Function (CRF) and the determination of the average cost of each health damage observation point. In the end we got a total scale of health damage externality with the mean value of 2678522*104 yuan, in which premature death took the largest part.

Effects of the COVID-19 Lockdown on Air Pollutant Levels and Associated Reductions in Ischemic Stroke Incidence in Shandong Province, China.

BackgroundLocal governments in China took restrictive measures after the outbreak of COVID-19 to control its spread, which unintentionally resulted in reduced anthropogenic emission sources of air pollutants. In this study, we intended to examine the effects of the COVID-19 lockdown policy on the concentration levels of particulate matter with aerodynamic diameters of ≤1 μm (PM1), ≤2.5 μm (PM2.5), and ≤10 μm (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and carbon monoxide (CO) and the potential subsequent reductions in the incidence of ischemic and hemorrhagic stroke in Shandong Province, China.MethodsA difference-in-difference model combining the daily incidence data for ischemic and hemorrhagic stroke and air pollutant data in 126 counties was used to estimate the effect of the COVID-19 lockdown on the air pollutant levels and ischemic and hemorrhagic stroke incident counts. The avoided ischemic stroke cases related to the changes in air pollutant exposure levels were further estimated using concentration-response functions from previous studies.ResultsThe PM1, PM2.5, PM10, NO2, and CO levels significantly decreased by −30.2, −20.9, −13.5, −46.3, and −13.1%, respectively. The O3 level increased by 11.5% during the lockdown compared with that in the counterfactual lockdown phase of the past 2 years. There was a significant reduction in population-weighted ischemic stroke cases (−15,315, 95% confidence interval [CI]: −27,689, −2,942), representing a reduction of 27.6% (95% CI: −49.9%, −5.3%). The change in the number of hemorrhagic stroke cases was not statistically significant. The total avoided PM1-, PM2.5-, PM10-, NO2-, and CO–related ischemic stroke cases were 739 (95% CI: 641, 833), 509 (95% CI: 440, 575), 355 (95% CI: 304, 405), 1,132 (95% CI: 1,024, 1,240), and 289 (95% CI: 236, 340), respectively.ConclusionThe COVID-19 lockdown indirectly reduced the concentration levels of PM1, PM2.5, PM10, NO2, and CO and subsequently reduced the associated ischemic stroke incidence. The health benefits due to the lockdown are temporary, and long-term measures should be implemented to increase air quality and related health benefits in the post-COVID-19 period.

Restrictions on indoor and outdoor NO2 emissions to reduce disease burden for pediatric asthma in China: A modeling study

SummaryBackgroundEpidemiological studies have reported the associations between nitrogen dioxide (NO2) and pediatric asthma incidence, but unable to ascertain indoor NO2 sources. We estimated the pediatric asthma incidence and corresponding economic losses attributable to NO2 from indoor and outdoor sources in urban areas in China.MethodsExposure to NO2 from indoor and outdoor sources in 2019 were estimated separately with a source-specific model validated by measurements from different studies, and NO2 exposure after restricting emissions indoor (from cooking or second-hand smoking) and outdoor (to meet WHO interim targets and air quality guideline) were projected. Disease burden of NO2-attributable new-onset pediatric asthma were estimated based on NO2 exposure, concentration-response function from a meta-analysis, and number of pediatric asthma populations. Economic impacts were estimated based on the costs of pediatric asthma in China.FindingsIn China, NO2 is associated with an estimated 637,000 (95% uncertainty interval 358,000–851,000) new pediatric asthma cases and 1,358 million (674–2145) RMB economic losses in urban areas in 2019. 296,000 (222,000–523,000) new pediatric asthma cases would be prevented each year by restricting NO2 emissions indoor, i.e., switching from using gas stoves to electic stoves for cooking. 393,000 (119,000–463,000) new pediatric asthma cases would be prevented each year when outdoor air meets the air quality guideline for NO2 (< 10 µg/m3).InterpretationRestricting both indoor and outdoor NO2 emissions are necessary to reduce pediatric asthma incidence in urban areas. NO2 restrictions may be achieved through clean energy transition and adoption of climate change mitigation activities.FundingVanke School of Public Health, Tsinghua University (2021JC005).

Mortality Attributable to Long-Term Exposure to Ambient Fine Particulate Matter: Insights from the Epidemiologic Evidence for Understudied Locations.

Epidemiologic cohort studies have consistently demonstrated that long-term exposure to ambient fine particles (PM2.5) is associated with mortality. Nevertheless, extrapolating results to understudied locations may involve considerable uncertainty. To explore this issue, this review discusses the evidence for (i) the associated risk of mortality, (ii) the shape of the concentration-response function, (iii) a causal interpretation, and (iv) how the source mix/composition of PM2.5 and population characteristics may alter the effect. The accumulated evidence suggests the following: (i) In the United States, the change in all-cause mortality risk per μg/m3 is about 0.8%. (ii) The concentration-response function appears nonlinear. (iii) Causation is overwhelmingly supported. (iv) Fossil fuel combustion-related sources are likely more toxic than others, and age, race, and income may modify the effect. To illustrate the use of our findings in support of a risk assessment in an understudied setting, we consider Kuwait. However, given the complexity of this relationship and the heterogeneity in reported effects, it is unreasonable to think that, in such circumstances, point estimates can be meaningful. Consequently, quantitative probabilistic estimates, which cannot be derived objectively, become essential. Formally elicited expert judgment can provide such estimates, and this review provides the evidence to support an elicitation.

Methods Matter: A Comparative Review of Health Risk Assessments for Ambient Air Pollution in Switzerland.

Objectives: Air pollution health risk assessments (AP-HRAs) provide a method to quantify health effects for entire populations. In Switzerland, AP-HRAs are included in Swiss assessments for Transport Externalities (STEs), ordered by public authorities since the 1990s. This study aimed to describe the differences among national and international AP-HRAs for Switzerland. Methods: We compared input data, approaches and results across AP-HRAs over time. Results and input data for each AP-HRA were expressed as a ratio compared to the most recent STE (in most cases STE-2010). Results: Substantial variation across AP-HRAs was found. For all-cause adult mortality attributed to particulate matter (the most frequent outcome-pollutant pair), the ratio in HRAs oscillated from 0.40 to 2.09 (times the STE-2010 value). Regarding input data, the ratio ranged from 0.69 to 1.26 for population exposure, from 0 to 1.81 for counterfactual scenario, from 0.96 to 1.13 for concentration-response function and from 1.03 to 1.13 for baseline health data. Conclusion: This study demonstrates that methods matter for AP-HRAs. Transparent and possibly standardized reporting of key input data and assumptions should be promoted to facilitate comparison of AP-HRAs.

Urban ambient air pollution and substance use disorder

There is growing evidence that air pollutants might affect human behavior. This study assesses the associations between air pollution concentrations and emergency department (ED) visits for abuse of psychoactive substances. 28,745 such ED visits were identified and retrieved from a health database containing diagnosed visits from five hospitals in Edmonton (Canada) over 10 years. The ED visits were analyzed as daily counts. Conditional Poisson regression models were used to estimate the associations between the number of ED visits and concentration levels of gaseous air pollutants (carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3)) and particulate matters (PM2.5 and PM10, fine and coarse, respectively). Air pollutants and weather factors in the realized statistical models were lagged by the same number of days, from 0 to 5 days. The associations were estimated in the form of concentration-response functions. The results show relative risks and their 95% confidence intervals. Positive and statistically significant associations were obtained for CO for all patients (lags from 0 to 5), males (lags 1 and 3–5), and females (lag 4). For NO2, exposure lagged by 1 and 2 days has a positive statistically significant association for all and male patients. PM10 shows the same type of associations lagged by 2 and 3 days. PM2.5 (lag 2) is associated only in females. The results indicate that urban air pollution may have an impact on the abuse of psychoactive substances.