Non-accidental Mortality Research Articles

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 <10 µg/m3 shapes indicated positive associations for concentrations >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.

Comparison of PM2.5 air pollution exposure estimates at WHIMS participant locations based on different modelling approaches and impact on health effects estimation

Background and Aim: Many approaches to quantifying air pollution exposures for use in epidemiologic analyses have been developed. However, whether exposure estimates from different approaches are comparable and whether choice of approach affects reported associations with health-related outcomes remains unclear. We compare PM2.5 concentrations at addresses from participants of the Women’s Health Initiative Memory Study (WHIMS) derived using multiple estimation approaches and assess differences in associated health effects estimates. Methods: We linked annual PM2.5 exposure estimates from 1999 to 2004 from 12 different approaches to WHIMS participant addresses from across the continental United States and restricted analyses to data from participants with stable addresses within each calendar year. Approaches included geo-statistical interpolation approaches, geographic information system (GIS)-based statistical models, air dispersion and chemical transport models, and hybrid models. We used descriptive statistics and visualizations to assess relative and absolute agreement of exposure estimates from different approaches across space and time and examined the impact of estimation approach on associations between PM2.5 and non-accidental mortality, CVD-related mortality, and incident CVD events. Results: Annual PM2.5 exposure estimates were reasonably similar across approaches, although the specific shapes and ranges of the distributions varied. Interquartile ranges tended to be similar, though ranges were more variable. Relative agreement was consistently higher than absolute agreement. After controlling for putative confounders, associations of PM2.5 with mortality and CVD were similar regardless of estimation approach. Conclusions: Agreement across different air pollution estimation approaches for PM2.5 was generally high when considering participants drawn from a broad geographic area, suggesting that all models predicted similar between-area differences. The implications of fine-scale variability between exposure estimation approaches warrants further investigation. Keywords: Air pollution, exposure assessment

Effect of different heat wave timing on non-accidental mortality in 20 French cities

BACKGROUND AND AIM: Previous epidemiological evidence suggests that the impact of heat waves on mortality may change over time (within and between summer seasons). The consideration of heat wave timing could help to optimize the alert systems, especially under a warming climate. The aim of this study was to explore the effect of heat wave timing on mortality risk during the summer season in France. METHODS: Summertime daily mortality data for 20 French cities from 2000 to 2015 were obtained from the French National Institute of Health and Medical Research. Heat waves were defined according to the official definition of Météo France. The order of heat wave over time, from June to September, was assessed. To quantify mortality risk for the first and second heat waves, quasi-Poisson with distributed-lag models were performed for each city. RESULTS: Overall, we found that, compared with non-heat wave days, the first heat wave of the summer season was associated with a higher risk ratio (RR) for cardiovascular mortality (RR: 1.32, 95% Confidence Interval [CI]:1.18-1.47) as compared to subsequent heat waves within the same summer (RR, 95% CI: 1.28, 1.14-1.44). We found the opposite pattern for respiratory mortality with RRs of 1.59 (95%CI:1.35-1.88) and 1.66 (95%CI: 1.32-2.07) for the first and second heat waves respectively. We identified important heterogeneity in such patterns across all cities. For cities such as Paris or Nancy, the first heatwave of the season resulted in a greater mortality risk. In contrast, for cities such as Lille, Marseille, or Rouen, the second heat wave was more impactful regarding mortality risk. CONCLUSIONS: The timing of heat waves events modulates heat-related risks in France. Such information could be used to update local heat action plans to optimize health benefits across French cities.

Associations between long-term exposure to air pollution and cause-specific mortality in River Sacco Valley area

BACKGROUND AND AIM: The River Sacco Valley is an industrial contaminated site in a central area of Italy. It is characterized by environmental pollution and socioeconomic deprivation. The study aim is to evaluate the chronic effects on cause-specific mortality of air pollution and socioeconomic deprivation (SEP) in an administrative cohort of residents in an industrial polluted site. METHODS: Subjects who were resident in River Sacco Valley between 2008 and 2018 were enrolled by linking administrative data. We collected information about age, sex, residential address and cause of death. Exposure to PM10, PM2.5, NO2, SO2, Benzene and O3 were assessed by FARM models for each residential address, while socioeconomic deprivation has been derived by an area-level indicator. Cox proportional hazard models adjusted by age (as time-scale), sex and city of residence were used to evaluate the effects of exposure to air pollutants and SEP to natural, cardiovascular, respiratory and malignancies mortality. RESULTS: 182578 subjects were enrolled in the cohort, among which 30% were aged 50+ years and 35% had high SEP. We observed 9205, 4019, 573, 2790 non-accidental, cardiovascular, respiratory and malignant cancer deaths, respectively. Each pollutant had average levels above the WHO guidelines standards. The results of main analysis showed positive hazard ratios (HR) per IQR increases up to 1.084 (95% confidence intervals: 0.99, 1.18) and 1.136 (0.99, 1.30) for PM10 and non-accidental and cardiovascular mortality, respectively. Furthermore, high deprivation was associated positively with each outcome. In particular, we registered HRs equals to 1.064 (0.98, 1.16) and 1.101 (0.97, 1.25) for non-accidental and cardiovascular mortality in high vs low SEP category. CONCLUSIONS: Living in a polluted site worse the health status for several causes. We observe that high levels of air pollutants and socioeconomic deprivation are linked to excess of risk of cause-specific mortality in the River Sacco Valley area.

The synergistic effects of Particle Radioactivity (Gross Beta Activity) and PM2.5 on Cardiovascular Diseases Mortality

BACKGROUND: Although the effects of fine particulate matter (particulate matter ≤2.5 μm aerodynamic diameter; PM₂.₅) on cardiovascular diseases (CVD) morbidity and mortality are well established, little is known about CVD health effects of particle radioactivity (PR). In addition, there are still questions about which of the PM₂.₅ physical, chemical, or biological properties are mostly responsible for its toxicity. METHODS: We investigated the association between PR, measured as gross β-activity from highly resolved spatiotemporal predictions, and mortality for CVD, myocardial infarction, stroke, and all-cause non-accidental mortality in Massachusetts (2001-2015). Within both difference-in-difference (DID) approach and generalized linear mixed-effect model frameworks, we fit gross β-activity-alone, PM2.5 alone, gross β-activity&PM₂.₅ models and examined the interaction between PM₂.₅ and gross β-activity. RESULTS: We found significant associations between gross β-activity/PM₂.₅ and each mortality cause. Using the DID approach and adjusting for PM₂.₅, we found the highest associations with MI (RR=1.16, 95% CI: 1.08, 1.24) and stroke (RR=1.11, 95% CI: 1.04, 1.18) for an IQR increase (0.055 mBq/m3) in gross β-activity. We found a significant positive interaction between PM₂.₅ and gross β-activity, with higher associations between PM₂.₅ and mortality at a higher level of gross β-activity. We also observed that the associations varied across age groups. The results were comparable between the two statistical methods with and without adjusting for PM₂.₅. CONCLUSIONS: This is the first study that, using highly spatiotemporal predictions of gross β-activity, provides evidence that PR increases CVD mortality and enhances PM₂.₅ CVD mortality. Therefore, PR can be an important property of PM₂.₅ that must be further investigated. Addressing this important question can lead to cost-effective air quality regulations. KEYWORDS: cardiovascular disease; death; particle radioactivity; death

Forecasting of non-accidental, cardiovascular, and respiratory mortality with environmental exposures adopting machine learning approaches.

Environmental exposure constantly changes with time and various interactions that can affect health outcomes. Machine learning (ML) or deep learning (DL) algorithms have been used to solve complex problems, such as multiple exposures and their interactions. This study developed predictive models for cause-specific mortality using ML and DL algorithms with the daily or hourly measured meteorological and air pollution data. The ML algorithm improved the performance compared to the conventional methods, even though the optimal algorithm depended on the adverse health outcomes. The best algorithms were extreme gradient boosting, ridge, and elastic net, respectively, for non-accidental, cardiovascular, and respiratory mortality with daily measurement; they were superior to the generalized additive model reducing a mean absolute error by 4.7%, 4.9%, and 16.8%, respectively. With hourly measurements, the ML model tended to outperform the conventional models, even though hourly data, instead of daily data, did not enhance the performance in some models. The proposed model allows a better understanding and development of robust predictive models for health outcomes using multiple environmental exposures.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-21768-9.

Health Disparity Resulting from the Effect of Built Environment on Temperature-Related Mortality in a Subtropical Urban Setting.

Whereas previous studies have assessed the overall health impact of temperature in Hong Kong, the aim of this study was to investigate whether the health impact is modified by local temperature of small geographic units, which may be related to the diverse socioeconomic characteristics of these units. The effects of local temperature on non-accidental and cause-specific mortality were analyzed using Bayesian spatial models at a small-area level, adjusting for potential confounders, i.e., area-level air pollutants, socioeconomic status, and green space, as well as spatial dependency. We found that a 10% increase in green space density was associated with an estimated 4.80% decrease in non-accidental mortality risk and a 5.75% decrease in cardiovascular disease mortality risk in Hong Kong, whereas variation in local annual temperature did not significantly contribute to mortality. We also found that the spatial variation of mortality within this city could be explained by the geographic distribution of green space and socioeconomic factors rather than local temperature or air pollution. The findings and methodology of this study may help to further understanding and investigation of social and structural determinants of health disparities, particularly place-based built environment across class-based small geographic units in a city, taking into account the intersection of multiple factors from individual to population levels.

Ambient formaldehyde and mortality: A time series analysis in China.

The potential health impact of low-level ambient formaldehyde has been historically overlooked. We conducted a two-stage time series analysis to investigate associations between ambient formaldehyde and daily nonaccidental, circulatory, and respiratory mortality and six subtypes based on 5,325,585 deaths in 275 Chinese counties between 2013 and 2018 and estimated a concentration-response curve to identify overall associations. After controlling for confounders from meteorological factors, air pollutants, time trend, and day of the week effect, with a 1-part per billion (ppb) increase in the daily concentration of formaldehyde on lag0 day, we found that mortality risks in nonaccidental, circulatory, and respiratory diseases increased by 0.36%, 0.36% and 0.41%, respectively. The curve indicated a possible threshold concentration at approximately 5 ppb for significant impact on nonaccidental and circulatory diseases. We suggest that ambient formaldehyde may represent a potential threat to public health and needs further investigation to support timely pollution regulation and health protection.

Short-term exposure to fine particulate matter constituents and mortality: case-crossover evidence from 32 counties in China.

A growing number of studies associated increased mortality with exposures to specific fine particulate (PM2.5) constituents, while great heterogeneity exists between locations. In China, evidence linking PM2.5 constituents and mortality was extensively sparse. This study primarily aimed to quantify short-term associations between PM2.5 constituents and non-accidental mortality among the Chinese population. We collected daily mortality records from 32 counties in China between January 1, 2011, and December 31, 2013. Daily concentrations of main PM2.5 constituents (organic carbon (OC), elemental carbon (EC), nitrate (NO3-), sulfate (SO42-), and ammonium (NH4+)) were estimated using the modified Community Multiscale Air Quality model. Time-stratified case-crossover design with conditional logistic regression models was adopted to estimate mortality risks associated with short-term exposures to PM2.5 mass and its constituents. Stratification analyses were done by sex, age, and season. A total of 116,959 non-accidental deaths were investigated. PM2.5 concentrations on the day of death were averaged at 75.7 µg m-3 (control day: 75.6 µg m-3), with an interquartile range (IQR) of 65.2 µg m-3. Per IQR rise in PM2.5, EC, OC, NO3-, SO42-, and NH4+ at lag-04 day was associated with an increase in non-accidental mortality of 2.4% (95% confidence interval, (1.0-3.7), 1.7% (0.8-2.7), 2.9% (1.6-4.3), 2.1% (0.4-3.9), 1.0% (0.2-1.9), and 1.6% (0.3-2.9), respectively. Both PM2.5 mass and its constituents were strongly associated with elevated cardiovascular mortality risks, but only PM2.5, EC, and OC were positively associated with respiratory mortality at lag-3 day. PM2.5 mass and its constituents associated effects on mortality varied among sex- and age-specific subpopulations. Differences in the seasonal pattern of associations exist among PM2.5 constituents, with stronger effects related to EC and NO3- in warm months but SO42- and NH4+ in cold months. Short-term exposures to PM2.5 compositions were positively associated with increased risks of mortality, particularly those constituents from combustion-related sources.

Impact of Heavy PM2.5 Pollution Events on Mortality in 250 Chinese Counties.

We explored the impact of heavy PM2.5 pollution events on the health of residents in 250 counties in China. A time-series approach involving a two-stage analysis was applied to estimate the association between heavy PM2.5 pollution events and mortality from 2013 to 2018. The associations between heavy (PM2.5 ≥75 μg/m3 and <150 μg/m3) and extremely heavy (PM2.5 ≥150 μg/m3) PM2.5 pollution days with mortality were explored. The added effects of the heavy PM2.5 pollution events were evaluated by controlling PM2.5 concentration in the model. From 2013 to 2018, there were 57,279 county days of heavy PM2.5 pollution and 21,248 county days of extremely heavy PM2.5 pollution. The risks of mortality during this period of heavy PM2.5 pollution events increased by 1.22% (95% CI: 0.82-1.63%), 1.14% (95% CI: 0.74-1.53%), 1.09% (95% CI: 0.58-1.60%), and 1.30% (95% CI: 0.40-2.20%), for all-cause, nonaccidental, circulatory, and respiratory mortality, respectively. We also observed that heavy PM2.5 pollution events had an added effect on mortality risk associated with all-cause, nonaccidental, circulatory, and respiratory mortality, evident from an observed increase by 0.77% (95% CI: 0.29-1.24%), 0.73% (95% CI: 0.27-1.19%), 0.96% (95% CI: 0.37-1.55%), and 0.55% (95% CI: -0.52-1.63%), respectively. Heavy PM2.5 pollution events increased mortality risks and caused an independent added effect. The findings serve as a foundation for policymakers in developing early warning systems and policy interventions.

Modification effects of ambient temperature on ozone-mortality relationships in Chengdu, China.

A multitude of epidemiological studies have demonstrated that both ambient temperatures and air pollution are closely related to health outcomes. However, whether temperature has modification effects on the association between ozone and health outcomes is still debated. In this study, three parallel time-series Poisson generalized additive models (GAMs) were used to examine the effects of modifying ambient temperatures on the association between ozone and mortality (including non-accidental, respiratory, and cardiovascular mortality) in Chengdu, China, from 2014 to 2016. The results confirmed that the ambient high temperatures strongly amplified the adverse effects of ozone on human mortality; specifically, the ozone effects were most pronounced at > 28°C. Without temperature stratification conditions, a 10-μg/m3 increase in the maximum 8-h average ozone (O3-8hmax) level at lag01 was associated with increases of 0.40% (95% confidence interval [CI] 0.15%, 0.65%), 0.61% (95% CI 0.27%, 0.95%), and 0.69% (95% CI 0.34%, 1.04%) in non-accidental, respiratory, and cardiovascular mortality, respectively. On days during which the temperature exceeded 28°C, a 10-μg/m3 increase in O3-8hmax led to increases of 2.22% (95% CI 1.21%, 3.23%), 2.67% (95% CI 0.57%, 4.76%), and 4.13% (95% CI 2.34%, 5.92%) in non-accidental, respiratory, and cardiovascular mortality, respectively. Our findings validated that high temperature could further aggravate the health risks of O3-8hmax; thus, mitigating ozone exposure will be brought into the limelight especially under the context of changing climate.

A Review: The Relationship between Daily Temperature with Non-Accidental Mortality and its Spatial Pattern in Peninsular Malaysia

Climate change is not only a future problem and an urgent identification of the population, assessing the health risk, and planning appropriate adaptation and mitigation policies is a must to protect human health.

Spatiotemporal relationship between temperature and non-accidental mortality: Assessing effect modification by socioeconomic status

BackgroundMost published studies have assessed the overall health impact of temperature by using one-station or multiple-station averaged meteorological and air quality data. Concern has arisen about whether the temperature health impact is homogeneous across the whole territory geographically, since green space and socioeconomic factors may modify the impact. ObjectiveThis study aims at investigating how small-area mortality is modified by local temperature and other meteorological, air quality, green space, and socioeconomic factors of small geographic units in a subtropical urban setting. MethodsData on meteorological, air pollutants, and non-accidental mortality count in Hong Kong during 2006–2016 were obtained. Combined with green space and socioeconomic data, spatiotemporal analysis using Generalized Additive Mixed Models was conducted to examine the temperature-mortality relationship, adjusted for seasonality, long-term trend, other meteorological factors, pollutants, socioeconomic characteristics and green space. ResultsSocioeconomic status was found to modify the temporal temperature-mortality relationship. A J-shape association was identified for most areas in Hong Kong, where a sharp increase of mortality was observed when daily minimum temperature dropped lower than the turning point. However, for people living in the most affluent areas, after the initial increase there was a decrease of mortality for colder days. Besides, when comparing the two spatiotemporal models (i.e. using nearby or central temperature monitoring station), while leaving the other predictors unchanged, this study showed that there was little difference in the overall model performances. ConclusionThis study indicated that the daily fluctuation of mortality was associated with daily temperature, while the spatial variation of mortality within this city could be explained by the geographical distribution of green space and socioeconomic factors. Since people living in affluent areas were found to be more tolerant of cold temperatures, it would be more efficient to tailor cold temperature health education and warning information for socioeconomically deprived communities.

Changes in mortality rate of the general population during the COVID-19 pandemic: an interrupted time series study in Korea.

Unlike other countries, South Korea did not implement a large-scale lockdown or closure of businesses to manage the coronavirus disease 2019 (COVID-19) pandemic, but relied on changes in population behaviours and early isolation and treatment of patients. It is important to evaluate the effectiveness of such alternative strategies on the mortality of the general population. Mortality and monthly population data from 2013 to 2020 were obtained. A quasi-Poisson regression model adjusting for age structure, seasonality and time was used to evaluate whether underlying trends for monthly mortality rate have changed with the pandemic. Stratification analyses based on sex and location of deaths (inside vs outside of medical facilities) were conducted. The risk estimates showed no changes in non-accidental mortality during the COVID-19 pandemic [relative risk (RR) (95% confidence interval, 95% CI), slope change: 1.00 (1.00, 1.01), step change: 0.99 (0.97, 1.01)] compared with those before the pandemic. In cause-specific analysis, there was an abrupt and sustained decrease in the mortality rate of respiratory diseases [RR (95% CI), step change: 0.81 (0.77, 0.84)]. In the analysis of deaths by location, an increase in non-accidental mortality [RR (95% CI), slope change: 1.01 (1.01, 1.02), step change: 1.16 (1.11, 1.22)] and several cause-specific mortalities was observed outside of medical facilities. The non-accidental mortality rate in South Korea for the first year of the pandemic followed the historical trends. However, there was a decrease in mortality associated with respiratory diseases, and an increase in mortality occurring outside of medical facilities. The findings may be attributed to changes in public behaviours, and availability of medical resources during the pandemic.

Ambient Temperature and External Causes of Death in Japan from 1979 to 2015: A Time-Stratified Case-Crossover Analysis

Background:Although substantial evidence suggests that high and low temperatures are adversely associated with nonaccidental mortality, few studies have focused on exploring the risks of temperature on external causes of death.Objectives:We investigated the short-term associations between temperature and external causes of death and four specific categories (suicide, transport, falls, and drowning) in 47 prefectures of Japan from 1979 to 2015.Methods:We conducted a two-stage meta-regression analysis. First, we performed time-stratified case-crossover analyses with a distributed lag nonlinear model to examine the association between temperature and mortality due to external causes for each prefecture. We then used a multivariate meta-regression model to combine the association estimates across all prefectures in Japan. In addition, we performed stratified analyses for the associations by sex and age.Results:A total of 2,416,707 external causes of death were included in the study. We found a J-shaped exposure–response curve for all external causes of death, in which the risks increased for mild cold temperatures [20th percentile; relative risk (95% confidence interval [CI]: 1.05,1.12)] and extreme heat [99th percentile; (95% CI: 1.20, 1.29)] compared with those for minimum mortality temperature (MMT). However, the shapes of the exposure–response curves varied according to four subcategories. The risks of suicide and transport monotonically increased as temperature increased, with RRs of 1.35 (95% CI: 1.26, 1.45) and 1.60 (95% CI: 1.35, 1.90), respectively, for heat, whereas J- and U-shaped curves were observed for falls and drowning, with RRs of 1.14 (95% CI: 1.03, 1.26) and 1.95 (95% CI: 1.70, 2.23) for heat and 1.13 (95% CI: 1.02, 1.26) and 2.33 (95% CI: 1.89, 2.88) for cold, respectively, compared with those for cause-specific MMTs. The sex- and age-specific associations varied considerably depending on the specific causes.Discussion:Both low and high temperatures may be important drivers of increased risk of external causes of death. We suggest that preventive measures against external causes of death should be considered in adaptation policies. https://doi.org/10.1289/EHP9943

Assessing the impact of green nudges on ozone concentration: Evidence from China's night refueling policy

Ozone (O3) pollution poses health risks and premature mortality, and gas stations are one of the largest sources of urban volatile organic compounds (VOCs, the main precursor to O3). This paper investigates whether the government's call for night refueling, which can be regarded as a green nudge, can guide changes in consumer behavior and consequently improve environmental quality. Using a difference-in-differences (DID) estimation and weekly monitoring site air quality panel data, we analyze the effect of the Night Refueling Preferential Policy on O3 concentrations. We find that the policy can reduce O3 concentrations by 10% by encouraging consumers to refuel at night. The reduction in O3 has brought great benefits to human health, leading to a 4–5‰ reduction in non-accidental mortality and a 6–8‰ reduction in cardiovascular mortality in Jiangsu province. The economic benefits of this policy would be approximately 62–189 billion Chinese Yuan (CNY) if it were implemented nationwide. The findings of this study suggest that the government can influence consumer behavior to promote environmental quality.

Associations between short-term ambient ozone exposure and cause-specific mortality in rural and urban areas of Jiangsu, China

Most previous studies on the acute health effects of ozone are limited to urban areas, largely due to the paucity of air pollutant measurements in rural areas. We here estimated the county-specific daily maximum 8-h average ozone concentration in Jiangsu Province, China during 2015–2018, using a recently developed spatiotemporal machine learning model at a spatial resolution of 0.1° × 0.1° (∼11 × 11 km). Counties were equally divided into urban and rural groups based on the median of the percentage of urban residents across Jiangsu counties obtained from the National Population Census in 2010. We first conducted time-series analyses to estimate the county-specific effect of ozone using generalized linear models, then pooled the effect estimates by random-effects modeling. A 10 μg/m3 increase in the 4-day moving average (lag 0–3) of ambient ozone exposure was associated with increases of 0.66% (95% confidence interval [CI] 0.36%–0.95%) in daily nonaccidental mortality in rural areas and 0.42% in urban areas (95% CI, 0.27%–0.56%). Short-term ambient ozone exposure was associated with an increased risk of mortality caused by chronic obstructive pulmonary disease, hypertension, ischemic heart disease, and stroke. Our finding suggests that both urban and rural residents suffer adverse health effects from short-term ozone exposure.

Air pollution and health impacts during the COVID-19 lockdowns in Grenoble, France

It is undeniable that exposure to outdoor air pollution impacts the health of populations and therefore constitutes a public health problem. Any actions or events causing variations in air quality have repercussions on populations’ health. Faced with the worldwide COVID-19 health crisis that began at the end of 2019, the governments of several countries were forced, in the beginning of 2020, to put in place very strict containment measures that could have led to changes in air quality. While many works in the literature have studied the issue of changes in the levels of air pollutants during the confinements in different countries, very few have focused on the impact of these changes on health risks. In this work, we compare the 2020 period, which includes two lockdowns (March 16 - May 10 and a partial shutdown Oct. 30 - Dec. 15) to a reference period 2015–2019 to determine how these government-mandated lockdowns affected concentrations of NO2, O3, PM2.5, and PM10, and how that affected human health factors, including low birth weight, lung cancer, mortality, asthma, non-accidental mortality, respiratory, and cardiovascular illnesses. To this end, we structured 2020 into four periods, alternating phases of freedom and lockdowns characterized by a stringency index. For each period, we calculated (1) the differences in pollutant levels between 2020 and a reference period (2015–2019) at both background and traffic stations; and (2) the resulting variations in the epidemiological based relative risks of health outcomes. As a result, we found that relative changes in pollutant levels during the 2020 restriction period were as follows: NO2 (−32%), PM2.5 (−22%), PM10 (−15%), and O3 (+10.6%). The pollutants associated with the highest health risk reductions in 2020 were PM2.5 and NO2, while PM10 and O3 changes had almost no effect on health outcomes. Reductions in short-term risks were related to reductions in PM2.5 (−3.2% in child emergency room visits for asthma during the second lockdown) and NO2 (−1.5% in hospitalizations for respiratory causes). Long-term risk reductions related to PM2.5 were low birth weight (−8%), mortality (−3.3%), and lung cancer (−2%), and to NO2 for mortality (−0.96%). Overall, our findings indicate that the confinement period in 2020 resulted in a substantial improvement in air quality in the Grenoble area.

Systematic review and meta-analysis of studies between short-term exposure to ambient carbon monoxide and non-accidental, cardiovascular, and respiratory mortality in China.

Although a growing number of original epidemiological studies imply a link between ambient pollution exposure and mortality risk, the findings associated with carbon monoxide (CO) exposure are inconsistent. Thus, we conducted a systematic review and meta-analysis of epidemiological studies to evaluate the correlations between ambient CO and non-accidental, cardiovascular, and respiratory mortality in China. Eight databases were searched from inception to 15 May 2021. A random-effect model was used to calculate the pooled relative risks (RRs) and 95% confidence intervals (CIs). Subgroup analyses as well as sensitivity analyses were performed. The I square value (I2) was used to assess heterogeneity among different studies. The assessment of publication bias on included studies was examined by funnel plot and Egger's test. The influence of a potential publication bias on findings was explored by using the trim-and-fill procedure. Ultimately, a total of 19 studies were included in our analysis. The pooled relative risk for each 1 mg/m3 increase of ambient carbon monoxide was 1.0220 (95%CI: 1.0102-1.0339) for non-accidental mortality, 1.0304 (95%CI:1.0154-1.0457) for cardiovascular mortality, and 1.0318 (95%CI:1.0132-1.0506) for respiratory mortality. None of subgroup analyses could explain the source of heterogeneity. Exclusion of any single study did not materially alter the pooled effect estimates. Although it was suggestive of publication bias, findings were generally similar with principal findings when we explored the influence of a potential publication bias using the trim-and-fill method. Our meta-analysis demonstrated that exposure to ambient CO was positive with risk of deaths from all non-accidental causes, total cardiovascular, and respiratory diseases. Based on these findings, tougher intervention policies and initiatives to reduce the health effects of CO exposure should be established.

Neighbourhood walkability and mortality: Findings from a 15-year follow-up of a nationally representative cohort of Canadian adults in urban areas.

Using a nationally representative cohort of Canadian adults, we assessed associations between neighbourhood walkability and cause-specific mortality and investigated whether they differed by socioeconomic status. The study population was drawn from the 2001 Canadian Census Health and Environment Cohort, which contains individual-level data from a random sample of 20% of Canadian households mandated to complete the long-form census. We included those aged≥25years at baseline who lived in urban and suburban areas. The national death registry was used to ascertain annual vital status. Linkages to annual income tax data provided place of residence. The Canadian Active Living Environments, a national index that summarizes walkability across Canadian neighbourhoods, was assigned to individuals' residential history. The Cox proportional hazards model was used to assess associations between walkability and cause-specific mortality. A total of 1.8 million participants (52.5% female) accrued 27.3 million person-years and 265 710 deaths during the 15-year follow-up. The adjusted hazard ratio (HR) for living in a highly walkable neighbourhood relative to living in the least walkable neighbourhoods was associated with a 9% (HR: 0.91 [0.88, 0.95]) and 3% (HR: 0.97 [0.94, 0.99]) reduced risk of cardiovascular and all non-accidental mortality, respectively. The strongest benefits of walkability were found among individuals within the lowest education and household income categories, and who lived in the most deprived neighbourhoods. There were no significant associations (most [class 5] versus least [class 1] walkable HR: 0.84 [0.61-1.16]) seen for accidental traffic mortality. Canadian adults who live in walkable neighbourhoods have lower rates of cardiovascular and non-accidental mortality, with the greatest benefits seen in those from the lowest socioeconomic groups.