Air Pollution and Deaths among Elderly Residents of São Paulo, Brazil: An Analysis of Mortality Displacement

The Effect of Particulate Matter Exposure on the Inflammatory Airway Response of Street Runners and Sedentary People

Physical exercise promotes many health benefits. However, its effects are not well known in a polluted environment. Thus, this study aimed to compare upper airway inflammatory responses between street runners and sedentary individuals. Twenty-eight volunteers were recruited: runners (n = 14) and sedentary individuals (n = 14), who lived and worked in the same metropolitan area of São Paulo, Brazil. Particulate matter (PM) levels were monitored ten weeks before winter (low PM levels) and ten weeks after the beginning of winter (high PM levels) [PM10 (p < 0.0001) and PM2.5 (p < 0.0001)]. The cytokines (TNF-α, IL-6, IL-10, and IL-17A) levels in the nasal lavage and fractional exhaled nitric oxide (FeNO) were taken at the beginning of the winter (baseline) and ten weeks afterwards (after ten weeks of high PM exposure). IL-6 concentration increased in both runners (p = 0.037) and sedentary individuals (p = 0.027) after high PM exposure compared to the baseline. IL-10 concentration increased in sedentary individuals (p = 0.037) while IL-17A levels were increased in runners (p = 0.001) after high PM exposure compared to the baseline. FeNO levels decreased in runners (p = 0.025) after high PM exposure compared to the baseline. Outdoor endurance training acts as an inducer of a differentiated immune response in the upper airways of runners compared to individuals with a sedentary lifestyle from the same community after elevated PM exposure.

Elderly Mortality and Exposure to Fine Particulate Matter and Ozone

BACKGROUND

The effects on particulate matter (PM) and ozone on health are being reported by a number of studies. The effects of these air pollutants are likely to be stronger in the elderly population, but studies in this regard are scarce. The purpose of this study was to study the effects of PM ≤ 2.5 μ and ozone on chronic health effects of the elderly population.

METHODS

In order to analyze the health status of the elderly population, National Statistical Office Mortality records were used. In this study, we calculated the number of deaths in Seoul of people who were 60 years or older between 2002 and 2012. The current study analyzed each disorder separately and the lag effect. PM and ozone were analyzed using the single exposure model, as well as the adjusted multi exposure model.

RESULTS

In the single exposure analysis with PM2.5 as the exposure variable, with the increase of 10 μ/m³, the number of deaths increased by 1.0039 fold, and vascular disease 1.0053 fold. In the multi exposure model adjusting for ozone, the number of deaths increased by 1.0037 fold, and vascular disease 1.0049 fold. In the single exposure analysis with ozone as the exposure variable, with the increase of 10 ppb, the number of deaths increased by 1.0038 fold, and in the multi exposure model adjusting for PM2.5, the number of deaths increased by 1.0027 fold. These results differed depending on the period or season. There was a 5-day lag effect between PM2.5 and deaths in the multi exposure model, and 1.0028 fold when adjusted for ozone. There was a 1-day lag effect in single exposure models with ozone as the main variable, and 1.0027 fold increase in deaths.

CONCLUSION

In our study, an increase in the number of deaths in the elderly population in accordance with the increase in the PM2.5 and ozone was found. The association found in our study could also influence socioeconomic burden. Future studies need to be performed in regards to younger population, as well as other air pollutants.

Generalized additive models: Building evidence of air pollution, climate change and human health

Advances in statistical analysis in the last few decades in the area of linear models enhanced the capability of researchers to study environmental procedures. In relation to general linear models; generalized linear models (GLM) provide greater flexibility in analyzing data related to non-normal distributions. Considering this, the current review explains various applications of the generalized additive model (GAM) to link air pollution, climatic variability with adverse health outcomes. The review examines the application of GAM within the varied field, focusing on the environment and meteorological data. Further, advantages and complications of applying GAM to environmental data are also discussed. Application of GAM allowed for specification for the error pattern and found to be an appropriate fit for the data sets having non-normal distributions; this results in lower and more reliable p-values. Since most environmental data is non-normal, GAM provides a more effective analytical method than traditional linear models. This review highlights on ambient air pollutants, climate change, and health by evaluating studies related to GAM. Additionally, an insight into the application of GAM in R software is provided, which is open source software with the extensive application for any type of dataset.

Cardiovascular and respiratory emergency dispatch due to short-term exposure to ambient PM10 in Dezful, Iran

Introduction: This study was conducted to determine the relation between exposure to particulate matter less than 10 microns (PM₁₀) caused by dust storms and the risk of cardiovascular, respiratory and traffic accident missions carried out by Emergency Medical Services (EMS).

Methods: This was a time-series study conducted in Dezful city, Iran. Daily information on the number of missions by the EMS due to cardiovascular, respiratory and crash problems and data on PM₁₀ were inquired from March 2013 until March 2016. A generalized linear model (GLM) with distributed lag models (DLMs) was used to evaluate the relation between the number of EMS missions and the average daily PM₁₀. The latent effects of PM₁₀ were estimated in single and cumulative lags, up to 14 days.

Results: In the adjusted model, for each IQR increase in the average daily PM₁₀ concentration, the risk of EMS missions in the total population in single lags of 2 to 7 days, and the cumulative lags of 0-7 and 0-14 days after exposure had a 0.8, 0.8, 0.8, 0.8, 0.7, 0.6, 6.7 and 1.4% significant increase. Also, for each IQR increase in the daily mean concentration of PM₁₀ in single 1 to 7, and cumulative lags of 0-2, 0-7, and 0-14 days after exposure, respectively, a 2.4, 2.7, 2.8, 2.9, 2.9, 2.7, 2.5, 7.4, 23.5 and 33. 3 % increase was observed in the risk of EMS cardiovascular missions.

Conclusion: Increase in daily PM₁₀ concentrations in Dezful is associated with an increase in the risk of EMS missions in lags up to two weeks after exposure.

Associations of ambient PM2.5 and O3 with cardiovascular mortality: a time-series study in Hefei, China

China is among the countries with the worst air quality throughout the world. As PM_2.5 was not included in the national air quality monitoring network before January 2013 in China, no study has investigated the associations of ambient PM_2.5 and O₃ with cardiovascular mortality in Hefei, China. In this time-series analysis, Poisson regression in generalized additive model was adopted to assess the associations between the air pollutants and cardiovascular mortality during the 2013-2015 in Hefei, China. The findings showed that the daily average level of PM_2.5 and O₃ was 77.8 μg/m³ and 60.1 μg/m³ in the study period, respectively. PM_2.5 and O₃ exposure tended to increase cardiovascular mortality, but the associations were statistically insignificant. Further stratified analyses by seasons showed that with every 10 μg/m³ increase of PM_2.5 in the cold season (October-March), the risk of cardiovascular death increased by 0.22% (95% CI 0.05%, 0.39%); while every 10 μg/m³ increase of O₃ in the warm season (April-September), the risk of cardiovascular death increased by 1.29% (95% CI 0.26%, 2.33%) on Lag0. Interestingly, stratified analysis by gender showed that the associations of PM_2.5, but not O₃ exposure, could significantly increase cardiovascular mortality in females, but not males. The findings of this study especially underscored the adverse associations of PM_2.5 and O₃ exposure with females in specific seasons. More studies are needed to verify our findings and further investigate the underlying mechanisms. Graphical Abstract.

Proinflammatory effects of dust storm and thermal inversion particulate matter (PM10) on human peripheral blood mononuclear cells (PBMCs) in vitro: a comparative approach and analysis

Particulate matter (PM) as the carcinogenic air pollutants can lead to aggravated health outcomes. Epidemiological studies demonstrated that PM can be engaged in different diseases such as cardiovascular, respiratory and cancer. The in vitro secretion of proinflammatory cytokines by human peripheral blood mononuclear cells (PBMCs) has been used to assess the effects of PM with an aerodynamic diameter < 10 μm (PM10). This study compared the proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and interleukin 1-beta (IL1-β) secretions of PBMCs exposed to PM10 of dust storm and inversion. We collected PM10 samples during the spring and autumn seasons in two locations. Isolated PBMCs were exposed separately to 50, 150, and 300 μg/ml of different type of PM10 for 4 and 24 h. The mean concentrations of TNF-α for the PM of dust storm and inversion were 6305.61 ± 2421 and 6651.74 ± 2820, respectively. Also the mean concentrations of IL1-β for the PM of dust storm and inversion were 556.86 ± 162 and 656.35 ± 196, respectively. Furthermore, these values for the production of IL-6 were 12,655 ± 5661 and 16,685 ± 8069, respectively. Although no significant difference was observed between the PM of dust storm and that of inversion with regard to PBMCs, the results showed a significant increase in the proinflammatory cytokine secretion of both PMs compared with the controls. Moreover, TNF-α, IL1-β, and IL-6 secreted in cells exposed to PM10 of dust storm were about 10 times more than the controls, these values for cells exposed to PM10 of inversion were around 10, 12, and 14 times more than the controls, respectively. It can be concluded that the PM10 of both dust storm and inversion can play a significant role in proinflammatory cytokine secretion due to its harmful effect on human health. Graphical abstractThis picture shows the Proinflammatory cytokine producing potential of PM10 with two sources (dust storm and urban air pollution) in exposure with human PBMCs in vitro.

Health benefit of air quality improvement in Guangzhou, China: Results from a long time-series analysis (2006-2016)

Numerous epidemiologic studies on adverse health effects of air pollution have been well documented; however, assessment on health benefits of air quality improvement from air pollution control measures has been limited in developing countries. We assessed the mortality benefits associated with air pollution improvement over 11 years in Guangzhou, China (2006-2016). A time series analysis with Generalized additive Poisson models was used to estimate mortality effects of ozone (O₃) and nitrogen dioxide (NO₂), adjusting for time trend, day of week, public holiday, temperature and relative humidity. We further estimated the changes in mortality burden of O₃ and NO₂, including attributable fraction (AF, in %) and attributable mortality (AM, in number of death) during study period. We lastly estimated mortality effects during the 2010 Asian Games (November 12 to December 18, 2010) compared to a baseline period consisting of 4-week before and 4-week after the game. During the study period, average annual concentrations of NO₂ decreased from 42.3 μg/m³ in 2006 to 33.8 μg/m³ in 2016; while O₃ levels remained stable over time. We observed significant increases in mortality of O₃ and NO₂, with approximately linear exposure-response relationships. In specific, each increase of 10 μg/m³ in O₃ and NO₂ at 2 prior days was associated with increases of 0.60% (95% confidence interval (CI): 0.47, 0.74) and 1.89% (95%CI: 1.49, 2.29) in total mortality, respectively. We further estimated that AF on total mortality attributed to NO₂ decreased from 1.38% (95%CI: 1.09, 1.68) in 2006-2010 to 0.43% (95%CI: 0.34, 0.52) in 2011-2016, corresponding to AM on total mortality of 2496 deaths (95%CI: 1964, 3033) to 1073 deaths (95%CI: 846, 1301). During the 2010 Asian Games, we observed decrease in total mortality of 9.3% (95%CI: -15.0, -3.2) in comparison with that observed in the baseline period. Similar mortality benefits in cardiovascular diseases were also observed. Our results showed reduced mortality burden from air pollution improvement in Guangzhou in recent years, which provide strong rationale for continuing to reduce air pollution through comprehensive and rigorous air quality management in the area.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Spatial variation in lag structure in the short-term effects of air pollution on mortality in seven major South Korean cities, 2006-2013

Lag is one of the major uncertainties in the heterogeneity of short-term effects of particulate matter with aerodynamic diameter <10 μm (PM₁₀) on mortality. This study aimed to explore spatial variations in extended lag effects of PM₁₀ on all-cause mortality, cardiovascular mortality and respiratory mortality in seven major South Korean cities over a period spanning 2006-2013. We did time-series analysis using generalized linear models and adjusted for temporal trend, day of the week, holiday, influenza epidemic, and weather. Single lag models and distributed lag models were extensively compared, specifically in terms of lag interval, and adjustment for temporal trend. We also conducted a time-stratified case-crossover analysis. Multivariate meta-regressions with city characteristic variables were conducted in order to assess spatial variation in the lag structure. When considering up to previous 45 days of exposure, we found longer lag associations between PM₁₀ and mortality, particularly in all-cause mortality and respiratory mortality. SO₂, the ratio of SO₂ to PM₁₀ and gross regional domestic product were all found to positively contribute towards the associations between PM₁₀ and all-cause mortality and cardiovascular mortality. Ulsan (Korea's largest industrial city) was found to have the strongest cumulative percentage increases in all-cause mortality and cardiovascular mortality per 10 μg/m³ increase of PM₁₀: 4.9% (95% CI: 2.5, 7.3) and 4.3% (95% CI: -0.9, 9.7) respectively. Busan (Korea's largest seaport city) was found to have the highest cumulative percentage increase in respiratory mortality with an 8.2% increase (95% CI: 2.8, 13.8). In summary, the short-term effects of PM₁₀ on mortality may persist over a period of not just few weeks but longer than a month, and may differ according to regional economy. This study provides public health implication that, in order to minimize the health effects of PM, air quality interventions should focus on not only particulate pollution but also gaseous pollution, such as SO₂.

Estimating mortality burden attributable to short-term PM2.5 exposure: A national observational study in China

Studies worldwide have estimated the number of deaths attributable to long-term exposure to fine airborne particles (PM2.5), but limited information is available on short-term exposure, particularly in China. In addition, most existing studies have assumed that short-term PM2.5-mortality associations were linear. For this reason, the use of linear exposure-response functions for calculating disease burden of short-term exposure to PM2.5 in China may not be appropriate. There is an urgent need for a comprehensive, evidence-based assessment of the disease burden related to short-term PM2.5 exposure in China. Here, we explored the non-linear association between short-term PM2.5 exposure and all-cause mortality in 104 counties in China; estimated county-specific mortality burdens attributable to short-term PM2.5 exposure for all counties in the country and analyzed spatial characteristics of the mortality burden due to short-term PM2.5 exposure in China. The pooled PM2.5-mortality association was non-linear, with a reversed J-shape. We found an approximately linear increased risk of mortality from 0 to 62 μg/m3 and decreased risk from 62 to 250 μg/m3. We estimated a total of 169,862 additional deaths from short-term PM2.5 exposure throughout China in 2015. Models using linear exposure-response functions for the PM2.5-mortality association estimated 32,186 deaths attributable to PM2.5 exposure, which is 5.3 times lower than estimates from the non-linear effect model. Short-term PM2.5 exposure contributed greatly to the death burden in China, approximately one seventh of the estimates from the chronic effect. It is essential and crucial to incorporate short-term PM2.5-related mortality estimations when considering the disease burden attributable to PM2.5 in developing countries such as China. Traditional linear effect models likely underestimated the mortality burden due to short-term exposure to PM2.5.

On inferences about lag effects using lag models in air pollution time-series studies

The choice of lag length is a matter of uncertainty in air pollution time-series studies. Lag models and model selections are widely used for inferences about lag effects, but there is lack of discussion on the integration of the two. We aimed to provide theoretical discussion on the performance of lag models, and the impact of model selections on inferences about lag effects. Bias and model selections based upon information criteria, statistical significance, effect size, and model averaging were discussed in the context of lag analysis. A simulation with eight of PM_2.5-mortality relation scenarios was also conducted in order to explore the performances of lag models and to compare the model selections. The application of lag models with an insufficient lag interval taken into account (i.e. insufficient lag models) provides biased estimates. We provided features of the model selections and showed their pitfalls in lag analysis of air pollution time-series studies. We also discussed limitations of meta-analysis which fails to consider the application of different lag models in individual studies. To foster exploration on air pollution-lag-response relations with relevant tools, we encourage researchers to compare different lag models in terms of effect estimates and variance estimates, and to report their favored models and competing models together based upon scientific knowledge supporting lag-response relations.

Summer-winter differences of PM2.5 toxicity to human alveolar epithelial cells (A549) and the roles of transition metals

Atmospheric fine particulate matters (PM_2.5) induce adverse human health effects through inhalation, and the harmful effects of PM_2.5 are determined not only by its air concentrations, but also by the particle components varied temporally. To investigate seasonal differences of the aerosol toxicity effects including cell viability and membrane damage, cell oxidative stress and responses of inflammatory cytokines, the human lung epithelial cells (A549) were exposed to PM_2.5 samples collected in both summer and winter by the in vitro toxicity bioassays. Toxicological results showed that, the PM_2.5 led to the cell viability decrease, cell membrane injury, oxidative stress level increase and inflammatory responses in a dose-dependent manner. Temporally, the cytotoxicity of winter PM_2.5 was higher than summer of this studied industrial area of Nanjing, China. According to the different contents of heavy metals accumulated in PM_2.5, the transition metals such as Cu might be an important contributor to the aerosol cell toxicity.

Temporal variations in ambient particulate matter reduction associated short-term mortality risks in Guangzhou, China: A time-series analysis (2006-2016)

Numerous studies have reported associations between ambient particulate matter (PM) and daily mortality; however, little is known about temporal variations in ambient air pollution associated mortality risks, particularly in developing countries with limited long time-series air monitoring data. In present study, we assessed the associations and temporal relationships between ambient PM and daily mortality in Guangzhou, China, during 2006-2016. With this unique 11-year dataset, we related daily concentrations of PM with aerodynamic diameter < 2.5 μm (PM_2.5), between 2.5 and 10 μm (PM_10-2.5) and <10 μm (PM₁₀) to daily mortality in Guangzhou. We applied overdispersed Poisson regression with adjustment for time trend and potential confounding factors. Multiple level sensitivity analyses were conducted to examine the robustness of main results. Between 2006 and 2016, annual concentrations of PM_2.5 decreased by 50.8% to 27.0 μg/m³, of PM_10-2.5 by 27.6% to 16.2 μg/m³, and of PM₁₀ by 44.1% to 43.3 μg/m³ in Guangzhou. In this study, per 10 μg/m³ increases in mean concentrations at current day and 6 prior days of death (lag06), we observed increases in total mortality risks of 0.55% (95% Confidence Interval (CI): 0.24%, 0.86%) for PM_2.5, 0.99% (95%CI: 0.48%, 1.50%) for PM_10-2.5, and 0.44% (95%CI: 0.22%, 0.65%) for PM₁₀. Stronger associations were observed for ambient PM on cardio-respiratory mortality and people at age ≥ 65 years. Despite drastic reductions in annual PM levels, PM_2.5 associated cardiovascular and respiratory mortality risks remained significant at 1.26% (95%CI: 0.19%, 2.35%) and 1.91% (95%CI: 0.25%, 3.60%) during 2014-2016. Further, PM_2.5 and PM₁₀ associated respiratory mortality risks showed increasing trend over time (p-value = 0.03 for PM_2.5). In summary, though ambient PM levels decreased substantially in Guangzhou in recent years, PM_2.5 and PM₁₀ associated cardio-respiratory mortality risks remained significant and respiratory mortality risks even increased. Our findings provide strong rationale for continuation of ambient air pollution control effort for public health protection in the future.

Association between Atmospheric Particulate Pollutants and Mortality for Cardio-Cerebrovascular Diseases in Chinese Korean Population: A Case-Crossover Study

Background: Air pollution in large Chinese cities has led to recent studies that highlighted the relationship between particulate matters (PM) and elevated risk of cardio-cerebrovascular mortality. However, it is unclear as to whether: (1) The same adverse relations exist in cities with relatively low levels of air pollution; and (2) the relationship between the two are similar across ethnic groups. Methods: We collected data of PM_2.5 (PM with an aerodynamic diameter ≤ 2.5 µm) and PM₁₀ (aerodynamic diameter ≤ 10 µm) in the Yanbian Korean Autonomous Prefecture between 1 January 2015 and 31 December 2016. Using a time-stratified case-crossover design, we investigated whether levels of particulate pollutants influence the risk of cardio-cerebrovascular disease mortality among ethnic Korean vs. ethnic Han residents residing in the Yanbian Korean Autonomous Prefecture. Results: Under the single air pollutant model, the odds ratios (ORs) of cardio-cerebrovascular disease were 1.025 (1.024–1.026) for each 10 μg/m³ increase in PM_2.5 at lag0 day, 1.012 (1.011–1.013) for each 10 μg/m³ increase in PM₁₀ at lag1 day. In the multi-pollutant model adjusted by PM₁₀, SO₂, and NO₂, the ORs of cardio-cerebrovascular disease were 1.150 (1.145–1.155) for ethnic Koreans and 1.154 (1.149–1.158) for ethnic Hans for each 10 μg/m³ increase in PM_2.5. In the multi-pollutant model adjusted by PM_2.5, SO₂, and NO₂, the ORs of cardio-cerebrovascular disease were 1.050 (1.047–1.053) for ethnic Koreans and 1.041 (1.039–1.043) for ethnic Hans for each 10 μg/m³ increase in PM₁₀. Conclusion: This study showed that PM_2.5 and PM₁₀ were associated with increased risks of acute death events in residential cardio-cerebrovascular disease in Yanbian, China.

Differential effects of size-specific particulate matter on emergency department visits for respiratory and cardiovascular diseases in Guangzhou, China

BACKGROUND

Studies differentiating the cardiorespiratory morbidity effects of PM_2.5, PM₁₀, and PM_2.5∼10 (i.e. coarse PM or PMc) are still limited and inconsistent.

OBJECTIVE

To estimate the acute, cumulative, and harvesting effects of exposure to the three size-specific PM on cardiorespiratory morbidity, and their concentration-response relations.

METHODS

A total of 6,727,439 emergency department (ED) visits were collected from 16 public teaching hospitals in Guangzhou, from January 1st 2012 to December 31st 2015, among which over 2.1 million were asthma, COPD, pneumonia, respiratory tract infection (RTI), hypertension, stroke, and coronary heart disease (CHD). Distributed lag non-linear models (DLNM) was used to estimate the associations between the three size-specific PM and ED visits for the cardiovascular diseases. Long-term trends, seasonality, influenza epidemics, meteorological factors, and other gas pollutants, including SO2, NO₂, and O₃, were adjusted. We stratified the analyses by gender and age.

RESULTS

Elevated PM_2.5 and PM₁₀ were significantly associated with increased ED visits for pneumonia, RTI, and CHD at both lag₀ and lag_0-3. A 10 μg/m³ increment of PMc (at lag_0-14) was estimated to increase ED visits for pneumonia by 6.32% (95% CI, 4.19, 8.49) and for RTI by 4.72% (95% CI, 3.81, 5.63), respectively. PMc showed stronger cumulative effects on asthma in children than elderly. We observed significant harvesting effects (i.e. morbidity displacements) of the three size-specific PM on respiratory but very little on cardiovascular ED visits. The concentration-response curves suggested non-linear relations between exposures to the three different sizes of PM and respiratory morbidity.

CONCLUSIONS

Overall, the three size-specific PM demonstrated distinct acute and cumulative effects on the cardiorespiratory diseases. PM_2.5 and PMc would have significant effects on pneumonia and RTI. Strategies should be considered to further reduce levels of ambient PM_2.5 and PMc.

Ambient air pollution and daily hospital admissions: A nationwide study in 218 Chinese cities

There have been few large multicity studies to evaluate the acute health effects of ambient air pollution on morbidity risk in developing counties. In this study, we examined the short-term associations of air pollution with daily hospital admissions in China. We conducted a nationwide time-series study in 218 Chinese cities between 2014 and 2016. Data on daily hospital admissions counts were obtained from the National Health Insurance Database for Urban Employees covering 0.28 billion enrollees. We used generalized additive model with Poisson regression to estimate the associations in each city, and we performed random-effects meta-analysis to pool the city-specific estimates. More than 60 million hospital admissions were analyzed in this study. At the national-average level, each 10 μg/m³ increase in PM₁₀, SO₂, and NO₂, and 1 mg/m³ increase in CO at lag 0 day was associated with a 0.29% (95% CI, 0.23%-0.36%), 1.16% (95% CI, 0.92%-1.40%), 1.68% (95% CI, 1.40%-1.95%), and 2.59% (95% CI, 1.69%-3.50%) higher daily hospital admissions, respectively. The associations of air pollution with hospital admissions remained statistically significant at levels below the current Chinese Ambient Air Quality Standards. The effect estimates were larger in cities with lower air pollutants levels or higher air temperatures and relative humidity, as well as in the elderly. In conclusion, our findings provide robust evidence of increased hospital admissions in association with short-term exposure to ambient air pollution in China.

Using rush hour and daytime exposure indicators to estimate the short-term mortality effects of air pollution: A case study in the Sichuan Basin, China

BACKGROUND

Daily mean concentrations of air pollutants have been widely used as exposure indicators to estimate the short-term mortality effects of outdoor air pollution. However, daily mean concentrations might insufficiently represent the true exposure level because of the diurnal variations of air pollutants and various human activity patterns. Daytime or rush-hour concentrations may lead to better estimations.

OBJECTIVE

Our study aimed to imitate the true exposure level under assumptions about human activity patterns and to examine the short-term mortality effects of the exposure to air pollution during a) the morning-evening rush hours (ME), b) the morning-lunch-evening rush hours (MLE), and c) the whole daytime (WDT) in Chengdu, Sichuan Basin, China.

METHODS

We investigated the diurnal variations of PM_2.5, SO₂, and O₃ and examined the associations between the three pollutants and nonaccidental mortality, cardiovascular mortality, respiratory mortality using generalized additive model. Three novel exposure indicators (ME, MLE, and WDT) were employed to imitate the most probable exposure levels. Relative change of excess risk (ER) was used to compare effects estimated from models with different exposure indicators.

RESULTS

In the relationship of PM_2.5 and mortality, ERs estimated from the novel-indicator models decreased by 4.88%-11.89% in comparison with ERs from the daily-indicator models. All the three novel indicators of SO₂ offered lower ERs of respiratory mortality than the daily indicator did. Significant associations were observed in O₃-nonaccidental mortality at lag0 in both winter and spring, and O₃-cardiovascular mortality at lag0 in winter. Overall, majority of effect estimates based on rush-hour or daytime indicators were lower than the estimates based on daily mean concentrations.

CONCLUSION

The use of daily mean concentrations may bias exposure assessment and thus inflating effect estimates. This study highlights the importance of rush-hour and daytime exposure and provides alternative indicators for estimating acute effects of air pollution.

Are ambient volatile organic compounds environmental stressors for heart failure?

BACKGROUND

Numerous epidemiological studies have indicated the adverse cardiovascular effects of air pollution on heart failure (HF) risk. However, little data are available directly evaluating the association of ambient volatile organic compounds (VOCs) with HF risk. We aimed to estimate the short-term effects of ambient VOCs on HF emergency hospitalizations in Hong Kong and to evaluate whether the associations were modified by sex and age.

METHODS

We collected the daily VOCs concentrations from the Hong Kong Environmental Protection Department between April 2011 to December 2014. HF emergency hospital admission data were obtained from the Hospital Authority of Hong Kong. Generalized additive model (GAM) integrated with the distributed lag model (DLM) was used to estimate the excess risks of HF emergency hospitalizations with ambient concentrations of each VOCs groups - alkane, alkene, alkyne, benzene and substituted benzene.

RESULTS

We observed short-term effects of alkyne and benzene on an increased risk of HF emergency hospitalizations. The cumulative effect over 0-6 lag days (dlm_0-6) for an IQR increment of alkyne (1.17 ppb) was associated with 4.2% (95% CI: 1.18%-7.26%) increases of HF emergency hospitalizations, while the corresponding effect estimate over dlm_0-2 for benzene per IQR (0.43 ppb) was 2.7% (95% CI: 0.39%-5.04%). Each VOCs groups was significantly associated with HF emergency hospitalizations in men.

CONCLUSIONS

Ambient volatile organic compounds, particularly alkyne and benzene, were associated with increased risks of heart failure in the Hong Kong population.

Association between ambient air pollution and daily hospital admissions for ischemic stroke: A nationwide time-series analysis

BACKGROUND

Evidence of the short-term effects of ambient air pollution on the risk of ischemic stroke in low- and middle-income countries is limited and inconsistent. We aimed to examine the associations between air pollution and daily hospital admissions for ischemic stroke in China.

METHODS AND FINDINGS

We identified hospital admissions for ischemic stroke in 2014-2016 from the national database covering up to 0.28 billion people who received Urban Employee Basic Medical Insurance (UEBMI) in China. We examined the associations between air pollution and daily ischemic stroke admission using a two-stage method. Poisson time-series regression models were firstly fitted to estimate the effects of air pollution in each city. Random-effects meta-analyses were then conducted to combine the estimates. Meta-regression models were applied to explore potential effect modifiers. More than 2 million hospital admissions for ischemic stroke were identified in 172 cities in China. In single-pollutant models, increases of 10 μg/m3 in particulate matter with aerodynamic diameter <2.5 μm (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) and 1 mg/m3 in carbon monoxide (CO) concentrations were associated with 0.34% (95% confidence interval [CI], 0.20%-0.48%), 1.37% (1.05%-1.70%), 1.82% (1.45%-2.19%), 0.01% (-0.14%-0.16%), and 3.24% (2.05%-4.43%) increases in hospital admissions for ischemic stroke on the same day, respectively. SO2 and NO2 associations remained significant in two-pollutant models, but not PM2.5 and CO associations. The effect estimates were greater in cities with lower air pollutant levels and higher air temperatures, as well as in elderly subgroups. The main limitation of the present study was the unavailability of data on individual exposure to ambient air pollution.

CONCLUSIONS

As the first national study in China to systematically examine the associations between short-term exposure to ambient air pollution and ischemic stroke, our findings indicate that transient increase in air pollution levels may increase the risk of ischemic stroke, which may have significant public health implications for the reduction of ischemic stroke burden in China.

Short-term effects of fine and coarse particles on deaths in Hong Kong elderly population: An analysis of mortality displacement

BACKGROUND

While numerous studies worldwide have evaluated the short-term associations of fine and coarse particulate matter (PM) air pollution with mortality and morbidity, these studies may be susceptible to short-term harvesting effect. We aimed to investigate the short-term association between mortality and PM with aerodynamic diameter less than 2.5 μm (PM_2.5) and those between 2.5 and 10 μm (PMc) within a month prior to death, and assess the mortality displacement by PM_2.5 and PMc among elderly population in Hong Kong.

METHODS

We obtained air pollution data from January 2011 to December 2015 from Environmental Protection Department, and daily cause-specific mortality data from Census and Statistical Department of Hong Kong. We performed generalized additive distributed lag model to examine the acute, delayed and long-lasting effects of PM_2.5 and PMc within one month on mortality.

RESULTS

We observed a statistically significant association of PM_2.5 and PMc exposure over lags 0-6 days with all natural mortality and cardio-respiratory mortality. The overall cumulative effect of PM_2.5 over 0-30 lag days was 3.44% (95% CI: 0.30-6.67%) increase in all natural mortality and 6.90% (95% CI: 0.58-13.61%) increase of circulatory mortality, which suggested the absence of mortality displacement by PM_2.5. On the other hand, no significant cumulative association with mortality was found for PMc over 0-30 lag exposure window, and thus mortality displacement by PMc cannot be ruled out. Findings remained robust in various sensitivity analyses.

CONCLUSIONS

We found adverse effect of both PM_2.5 and PMc exposure within one week prior to death. While there was no evidence of mortality displacement in the association of PM_2.5 exposure over one month prior with all natural and circulatory mortality, mortality displacement by PMc cannot be ruled out. PM_2.5 may contribute more to the longer term effect of particulate matter than PMc.

Cardiorespiratory health effects of gaseous ambient air pollution exposure in low and middle income countries: a systematic review and meta-analysis

BACKGROUND

Lack of research on the effects of gaseous pollutants (nitrogen oxides [NO_x], sulfur dioxide [SO₂], carbon monoxide [CO] and ozone [O₃]) in the ambient environment on health outcomes from within low and middle income countries (LMICs) is leading to reliance on results from studies performed within high income countries (HICs). This systematic review and meta-analysis examines the cardiorespiratory health effects of gaseous pollutants in LMICs exclusively.

METHODS

Systematic searching was carried out and estimates pooled by pollutant, lag and outcome, and presented as excess relative risk per 10 μg/m³ (NO_x, SO₂, O₃) or 1 ppm (CO) increase pollutant. Sub-group analysis was performed examining estimates by specific outcomes, city and co-pollutant adjustment.

RESULTS

Sixty studies met the inclusion criteria, most (44) from the East Asia and Pacific region. A 10 μg/m³ increase in same day NOx was associated with 0.92% (95% CI: 0.44, 1.39), and 0.70% (0.01, 1.40) increases in cardiovascular and respiratory mortality respectively, same day NO_x was not associated with morbidity. Same day sulfur dioxide was associated with 0.73% (0.04, 1.42) and 0.50% (0.01, 1.00) increases in respiratory morbidity and in cardiovascular mortality respectively.

CONCLUSIONS

Acute exposure to gaseous ambient air pollution (AAP) is associated with increases in morbidity and mortality in LMICs, with greatest associations observed for cardiorespiratory mortality.

Short-term Effect of Ambient Ozone on Daily Emergency Room Visits in Beijing, China

Little is known about the acute effects of ozone on morbidity risk in China. We conducted a time-series study to examine the association between ozone and daily emergency room visits (ERVs) in Beijing, China. We identified 7,088,309 ERVs between January 1, 2014 and December 31, 2015. A generalized additive model with Poisson regression incorporating penalized spline functions was employed to analyze ERVs in association with daily 8-h maximum ozone concentrations. An increase of 10 μg/m³ of same-day ozone concentration was significantly associated with a 0.24% (95% CI, 0.21%–0.26%), 0.31% (95% CI, 0.27%–0.35%), and 0.43% (95% CI, 0.36%–0.50%) increase in daily ERVs for the whole study period, days when the daily 8-h maximum ozone met the Chinese Ambient Air Quality Standards (CAAQS) Grade II standard, and days that met the CAAQS Grade I standard, respectively. These results were robust when considering the potential confounding effects of PM_2.5, PM₁₀, NO₂, SO₂, and CO. In conclusion, our findings suggested significant effects of ozone exposure on daily ERVs in Beijing. Improving air quality with even lower ozone level than the current CAAQS could yield important public health.

Cardiorespiratory health effects of particulate ambient air pollution exposure in low-income and middle-income countries: a systematic review and meta-analysis

BACKGROUND

Most prospective studies on the health effects of particulate ambient air pollution exposure have focused on high-income countries, which have much lower pollutant concentrations than low-income and middle-income countries (LMICs) and different sources of pollution. We aimed to investigate the cardiorespiratory health effects of particulate ambient air pollution exposure in LMICs exclusively.

METHODS

For this systematic review and meta-analysis, we searched PubMed, Web of Science, Embase, LILACS, Global Health, and Proquest for studies published between database inception and Nov 28, 2016, investigating the cardiorespiratory health effects of particulate ambient air pollution exposure in LMICs. Data were extracted from published studies by one author, and then checked and verified by all authors independently. We pooled estimates by pollutant type (particulate matter with a diameter of <2·5 μm [PM_2·5] or 2·5-10 μm [PM₁₀]), lag, and outcome, and presented them as excess relative risk per 10 μg/m³ increase in particulate ambient air pollution. We used a random-effects model to derive overall excess risk. The study protocol is registered with PROSPERO, number CRD42016051733.

FINDINGS

Of 1553 studies identified, 91 met the full eligibility criteria. Only four long-term exposure studies from China were identified and not included in the meta-analysis. A 10 μg/m³ increase in same-day PM_2·5 was associated with a 0·47% (95% CI 0·34-0·61) increase in cardiovascular mortality and a 0·57% (0·28-0·86) increase in respiratory mortality. A 10 μg/m³ increase in same-day PM₁₀ was associated with a 0·27% (0·11-0·44) increase in cardiovascular mortality and a 0·56% (0·24-0·87) increase in respiratory mortality.

INTERPRETATION

Short-term exposure to particulate ambient air pollution is associated with increases in cardiorespiratory morbidity and mortality in LMIC's, with apparent regional-specific variations.

FUNDING

None.

Associations of short-term exposure to ambient air pollutants with emergency ambulance calls for the exacerbation of essential arterial hypertension

We investigated the association between daily emergency ambulance calls (EAC) for elevated blood pressure that occurred during the time intervals of 8:00-13:59, 14:00-21:59, and 22:00-7:59, and exposure to CO, PM₁₀, and ozone. We used Poisson regression to explore the association between the risk of EAC and short-term variation of pollutants, adjusting for seasonality and weather variables. Before noon, the risk was associated with an interquartile range (IQR) (7.9 μg/m³) increase in PM₁₀ at lag 2-4 days below the median (RR = 1.08, p = 0.031) and with an IQR (0.146 mg/m³) increase in CO at lag 6-7 below the median (RR = 1.05, p = 0.028). During 14:00-21:59, the risk was associated with an IQR (18.8 μg/m³) increase in PM₁₀ on the previous day below the median (RR = 1.04, p = 0.031). At night, EAC were negatively affected by lower O₃ (lag 0-2) below the median (per IQR decrease RR = 1.10, p = 0.018) and a higher PM₁₀ at lag 0-1 above the median for the elderly (RR = 1.07, p = 0.030).

Effects of NO2 exposure on daily mortality in São Paulo, Brazil

BACKGROUND

Recent reports have suggested that air pollution mixtures represented by nitrogen dioxide (NO₂) may have effects on human health, which are independent from those of particulate matter mass. We evaluate the association between NO₂ and daily mortality among elderly using one- and multipollutant models.

METHODS

This study was a daily time series of non-accidental and cause-specific mortality among the elderly living in São Paulo, Brazil, between 2000 and 2011. Effects of NO₂, particulate matter smaller than 10µm (PM10), carbon monoxide (CO) and ozone (O₃) were estimated in Poisson generalized additive models. The single lag effect at lags 0 and 1 days and the cumulative effect from 0 to lag 10 days were evaluated in one-, two-, three- and four-pollutant models. The cumulative risk index (CRI) recently proposed to analyze associations with health of multiple correlated pollutants was additionally estimated for each multipollutant model.

RESULTS

An association between NO₂, PM10, CO and O₃ exposures and non-accidental and cause-specific deaths was found in one-pollutant models. NO₂ effects remained significant in multipollutant models for non-accidental and circulatory deaths. The estimated CRIs suggested that circulatory deaths were mainly associated with NO₂, and respiratory deaths mainly with CO and O₃, regardless the lag. For non-accidental deaths, multipollutant models were associated with the highest CRI, with the main pollutants depending on the chosen lag.

CONCLUSIONS

The results suggest that air pollution mixtures represented by NO₂ have an effect on non-accidental and circulatory mortality, which is independent from PM10, CO and O₃. The CRI was always larger than the risks associated with single pollutants.

Fine Particulate Air Pollution and Daily Mortality. A Nationwide Analysis in 272 Chinese Cities

RATIONALE

Evidence concerning the acute health effects of air pollution caused by fine particulate matter (PM_2.5) in developing countries is quite limited.

OBJECTIVES

To evaluate short-term associations between PM_2.5 and daily cause-specific mortality in China.

METHODS

A nationwide time-series analysis was performed in 272 representative Chinese cities from 2013 to 2015. Two-stage Bayesian hierarchical models were applied to estimate regional- and national-average associations between PM_2.5 concentrations and daily cause-specific mortality. City-specific effects of PM_2.5 were estimated using the overdispersed generalized additive models after adjusting for time trends, day of the week, and weather conditions. Exposure-response relationship curves and potential effect modifiers were also evaluated.

MEASUREMENTS AND MAIN RESULTS

The average of annual mean PM_2.5 concentration in each city was 56 μg/m³ (minimum, 18 μg/m³; maximum, 127 μg/m³). Each 10-μg/m³ increase in 2-day moving average of PM_2.5 concentrations was significantly associated with increments in mortality of 0.22% from total nonaccidental causes, 0.27% from cardiovascular diseases, 0.39% from hypertension, 0.30% from coronary heart diseases, 0.23% from stroke, 0.29% from respiratory diseases, and 0.38% from chronic obstructive pulmonary disease. There was a leveling off in the exposure-response curves at high concentrations in most, but not all, regions. The associations were stronger in cities with lower PM_2.5 levels or higher temperatures, and in subpopulations with elder age or less education.

CONCLUSIONS

This nationwide investigation provided robust evidence of the associations between short-term exposure to PM_2.5 and increased mortality from various cardiopulmonary diseases in China. The magnitude of associations was lower than those reported in Europe and North America.