652个城市的大气颗粒物污染与每日死亡率的关系

近年来关于空气颗粒物污染对健康危害的研究越来越多,但由于不同的建模方法及潜在的发表偏倚,使得研究结果的系统评估难度较大。本研究收集了24个国家和地区的652个城市的居民每日死亡数据和空气污染数据,使用具有随机效应荟萃分析的超分散广义相加模型对PM10和PM2.5与总死亡率、心血管疾病死亡率和呼吸道疾病死亡率的关系进行评估,并拟合出具有全球代表性的颗粒物暴露反应关系曲线。     

Interactions between particulate air pollution and temperature in air pollution mortality time series studies

In many community time series studies on the effect of particulate air pollution on mortality, particulate air pollution is modeled additively. In this study, we investigated the interaction between daily particulate air pollution and daily mean temperature in Cook County, Illinois and Allegheny County, Pennsylvania, using data for the period 1987-1994. This was done through the use of joint particulate air pollution-temperature response surfaces and by stratifying the effect of particulate air pollution on mortality by temperature. Evidence that the effect of particulate air pollution on mortality may depend on temperature is found. However, the results were sensitive to the number of degrees of freedom used in the confounder adjustments, the particulate air pollution exposure measure, and how the effects of temperature on mortality are modeled. The results were less sensitive to the estimation method used--generalized linear models and natural cubic splines or generalized additive models and smoothing splines. The results of this study suggest that in community particulate air pollution mortality time series studies the possibility of an interaction between daily particulate air pollution and daily mean temperature should be considered.     

Associations between mortality and air pollution in central Europe

Increased mortality has been observed in association with elevated concentrations of air pollutants in European cities and in the United States. We reassessed the effects of particulate matter in Central Europe. Mortality and air pollution data were obtained for a highly polluted region of the Czech Republic and a rural region in Germany. Poisson regression analyses were conducted considering trend, season, meteorology, and influenza epidemics as confounders in both a parametric and a nonparametric approach. The Czech Republic had a 3.8% increase in mortality [95% confidence interval (CI), 0.8-6.9%] in association with 100 microg/m(3) total suspended particles (TSP) (lagged 2 days) for the time period 1982-1994. During the last 2 years of study, 68% of the TSP consisted of particulate matter [less than/equal to] 10 microm in aerodynamic diameter (PM(10)). An increase of 100 microg/m(3) TSP (lagged 1 day) was associated with a 9.5% increase in mortality (CI, 1.2-18.5%) and 100 microg/m(3) PM(10 )(lagged 1 day) showed a 9.8% increase in mortality (CI, 0.7-19.7%). We found no evidence for an association between mortality and particulate matter in the rural area in Germany at the Czech border. Data from the coal basin in the Czech Republic suggested an increase in mortality associated with the concentration of particulate matter in a highly polluted setting in Central Europe that is consistent with the associations observed in other western European cities and in the United States.     

广州市中心城区冬季大气PM2.5污染状况与居民每日死亡的关系

目的了解2013年广州市中心城区冬季PM2.5污染特征及其对居民死亡的影响。方法于2013年11和12月,每月10—16日采集广州中心城区大气PM2.5样本,分析样本中的12种金属元素(Pb、Mn、Al、Cd、Cr、Sb、As、Be、Hg、Ni、Se、Ti)、4种无机水溶性离子(NO3-、SO42-、NH4+和Cl-)和16种多环芳烃(PAHs);收集2013年度中心城区的大气PM2.5日平均浓度和2013年居民的每日死亡数据,利用广义相加时间序列模型分析大气PM2.5日平均浓度与居民非意外总死亡、呼吸系统疾病和心血管疾病死亡的关系。结果 PM2.5中,无机水溶性离子质量所占比例最高(38.29%),其中NO3-平均浓度最高(14.42μg/m3),其次是SO42-(13.94μg/m3);金属成分中Al的含量最高(239.99 ng/m3),其次是Pb(138.15 ng/m3);多环芳烃中苯并[b]荧蒽(Bb F)的含量最高(3.96 ng/m3),其次是荧蒽(Flu)(3.61 ng/m3),苯并[a]芘(Ba P)为2.89 ng/m3。时间序列分析显示,大气中PM2.5浓度在滞后1d时非意外总死亡的健康效应最大,PM2.5浓度每升高10μg/m3居民非意外总死亡率升高1.20%(95%CI:0.63%~1.77%);在滞后3 d时心血管疾病的死亡效应最大,PM2.5每升高10μg/m3居民心血管疾病死亡率升高1.41%(95%CI:0.62~2.21%),未发现PM2.5对于呼吸系统疾病的死亡有显著的影响(lag0~lag3)。结论广州市中心城区大气PM2.5吸附的无机水溶性离子以NO3-和SO42-为主,PM2.5浓度的升高会引起相关疾病,尤其是心血管疾病死亡率的增加。     

Fine particulate matter constituents and cardiopulmonary mortality in a heavily polluted Chinese city

Background: Although ambient fine particulate matter (PM_2.5; particulate matter ≤ 2.5 µm in aerodynamic diameter) has been linked to adverse human health effects, the chemical constituents that cause harm are unknown. To our knowledge, the health effects of PM_2.5 constituents have not been reported for a developing country.Objectives: We examined the short-term association between PM_2.5 constituents and daily mortality in Xi’an, a heavily polluted Chinese city.Methods: We obtained daily mortality data and daily concentrations of PM_2.5, organic carbon (OC), elemental carbon (EC), and 10 water-soluble ions for 1 January 2004 through 31 December 2008. We also measured concentrations of fifteen elements 1 January 2006 through 31 December 2008. We analyzed the data using over-dispersed generalized linear Poisson models.Results: During the study period, the mean daily average concentration of PM_2.5 in Xi’an was 182.2 µg/m³. Major contributors to PM_2.5 mass included OC, EC, sulfate, nitrate, and ammonium. After adjustment for PM_2.5 mass, we found significant positive associations of total, cardiovascular, or respiratory mortality with OC, EC, ammonium, nitrate, chlorine ion, chlorine, and nickel for at least 1 lag day. Nitrate demonstrated stronger associations with total and cardiovascular mortality than PM_2.5 mass. For a 1-day lag, interquartile range increases in PM_2.5 mass and nitrate (114.9 and 15.4 µg/m³, respectively) were associated with 1.8% [95% confidence interval (CI): 0.8%, 2.8%] and 3.8% (95% CI: 1.7%, 5.9%) increases in total mortality.Conclusions: Our findings suggest that PM_2.5 constituents from the combustion of fossil fuel may have an appreciable influence on the health effects attributable to PM_2.5 in Xi’an.     

Association between EMS calls and fine particulate air pollution in Utah

Multiple studies have noted an association between ambient air pollution and cardiovascular and pulmonary disease. Our goal was to investigate the potential relationship between fine particulate air pollution and emergency medical services (EMS) calls with a particular focus on cardiovascular and respiratory complaints. Utilizing a database of 911 emergency calls from the National EMS Information System, we analyzed 322,097 eligible EMS encounters in Utah over a 4-year period. We evaluated the relationship between the health emergency, as noted by the EMS provider’s primary impression, and short-term exposure to fine particulate matter (aerodynamic diameter ≤2.5-μm cut point (PM_2.5)), as recorded by the United States Environmental Protection Agency (EPA) Air Quality System (AQS). Using a case crossover design and conditional logistic regression, we analyzed the association between health emergencies and PM_2.5 concentrations over varying time exposures. At the 95 % confidence level, we found significant associations only between pollution exposure and EMS calls for diabetic symptoms (using pollution from the concurrent day) and syncope/fainting (using pollution from the concurrent day and from 2- to 5-day lagged moving averages). We found no other significant positive associations between health emergencies and PM_2.5 concentration. In particular, we noted no association between daily PM_2.5 concentration and EMS calls for cardiac arrest, chest pain, or respiratory distress. We found limited association between ambient air pollution and health emergencies, as classified by the EMS provider’s impression. We noted no association with primary cardiovascular or respiratory complaints.     

The effects of components of fine particulate air pollution on mortality in california: results from CALFINE

OBJECTIVE: Several epidemiologic studies provide evidence of an association between daily mortality and particulate matter < 2.5 pm in diameter (PM2.5). Little is known, however, about the relative effects of PM2.5 constituents. We examined associations between 19 PM2.5 components and daily mortality in six California counties. DESIGN: We obtained daily data from 2000 to 2003 on mortality and PM2.5 mass and components, including elemental and organic carbon (EC and OC), nitrates, sulfates, and various metals. We examined associations of PM2.5 and its constituents with daily counts of several mortality categories: all-cause, cardiovascular, respiratory, and mortality age > 65 years. Poisson regressions incorporating natural splines were used to control for time-varying covariates. Effect estimates were determined for each component in each county and then combined using a random-effects model. RESULTS: PM2.5 mass and several constituents were associated with multiple mortality categories, especially cardiovascular deaths. For example, for a 3-day lag, the latter increased by 1.6, 2.1, 1.6, and 1.5% for PM2.5, EC, OC, and nitrates based on interquartile ranges of 14.6, 0.8, 4.6, and 5.5 pg/m(3), respectively. Stronger associations were observed between mortality and additional pollutants, including sulfates and several metals, during the cool season. CONCLUSION: This multicounty analysis adds to the growing body of evidence linking PM2.5 with mortality and indicates that excess risks may vary among specific PM2.5 components. Therefore, the use of regression coefficients based on PM2.5 mass may underestimate associations with some PM2.5 components. Also, our findings support the hypothesis that combustion-associated pollutants are particularly important in California.     

Synoptic weather modeling and estimates of the exposure-response relationship between daily mortality and particulate air pollution.

This study estimated the association between particulate air pollution and daily mortality in Utah Valley using the synoptic climatological approach to control for potential weather effects. This approach was compared with alternative weather modeling approaches. Although seasonality explained a significant amount of variability in mortality, other weather variables explained only a very small amount of additional variability in mortality. The synoptic climatological approach performed as well or slightly better than alternative approaches to controlling for weather. However, the estimated effect of particulate pollution on mortality was mostly unchanged or slightly larger when synoptic categories were used to control for weather. Furthermore, the shape of the estimated dose-response relationship was similar when alternative approaches to controlling for weather were used. The associations between particulate pollution and daily mortality were not significantly different from a linear exposure-response relationship that extends throughout the full observed range of pollution.     

Particulate air pollution and daily mortality: a synthesis.

Episodes of high concentrations of particulate-based fog were associated with substantial increases in daily mortality earlier in this century. The sharp rise and fall of mortality with equally dramatic changes in air pollution left little doubt about causality. Other studies have shown associations of daily fluctuations in particulate-based air pollution and daily mortality in long time series. These associations continued to quite low concentrations of air pollution, although the optical-based measures do not readily allow direct comparisons with current pollution measurement techniques. This paper reports the results of seven studies examining the relationship between gravimetrically measured airborne particles and daily mortality. In Poisson regressions controlling for weather, time trends, and serial correlation, TSP or PM10 were significantly associated with daily mortality. The association with particles was independent of SO2, but not vice versa. The similarity of the regression coefficients among the studies was striking, and suggests that a 100 micrograms/m3 increase in daily TSP concentrations is associated with about a 6% increase in mortality. The same coefficient also suffices to explain the more than two-fold increase in mortality in London in 1952. The use of covariate adjusted quintile plots showed no evidence of a threshold down to concentrations of 40 micrograms/m3 or less. The relationship was significant in St. Louis, where daily concentrations of PM10 never exceeded 97 micrograms/m3. Given the similar results in all six studies, and the strong associations recently reported between particles and morbidity, the association is likely causal.     

Association between daily mortality from respiratory and cardiovascular diseases and air pollution in Taiwan

Background

Many studies have investigated the effects of air pollutants on disease and mortality. However, the results remain inconsistent and inconclusive. We thought that the impact of different seasons or ages of people may explain these differences.

Methods

Measurement of the five pollutants (particulate matter <10 μm in aerodynamic diameter (PM₁₀), SO₂, NO₂, O₃, and CO) was monitored by automated measuring units at five different stations. Monitoring stations were provided by the Taiwan Environmental Protection Agency (EPA) from 1997 to 1999. The subjects in the study were classified in two groups: those 65 years of age and older, and those of all ages (including the subjects in the ?65 group). Data on daily mortality caused by respiratory disease, cardiovascular disease, and all other causes including the two aforementioned was collected by the Taiwan Department of Health (DOH). A time-series regression model was used to analyze the relative risk of respiratory and cardiovascular diseases due to air pollution in the summer and winter seasons.

Results

Risk of death from all causes and mortality from cardiovascular diseases during winter was significantly positively correlated with levels of SO₂, CO, and NO₂ for both groups of subjects and additionally with PM₁₀ for the elderly (?65 years old) group. There were significant positive correlations with respiratory diseases and levels of O₃ for both groups. However, the only significant positive correlation was with O₃ (RR=1.283) for the elderly group during summer. No other parameters showed significance for either group.

Conclusion

Our findings contribute to the evidence of an association between SO₂, CO, NO₂, and PM₁₀ and mortality from respiratory and cardiovascular diseases, especially among elderly people during the winter season.     

空气颗粒物与呼吸及心脑血管疾病每日住院率相关性研究

目的 建立颗粒物空气污染与每日住院率暴露反应关系模型,为颗粒物空气污染健康影响早期预警提供科学依据.方法 应用]Poisson广义可加模型鉴定暴露反应关系形状,分段线性拟合进行污染物危险度评估.结果 年龄分组分析:颗粒物空气污染与所有年龄组每日住院率均呈正相关,且为非线性.可吸入颗粒物每增加10 ìg/m3,呼吸系统疾病住院率上升百分比为0.716%～2.145%,心脑血管疾病住院率上升百分比为0.65%.病因分组分析:颗粒物空气污染与所有疾病每日住院率均呈正相关,且为非线性.影响显著的疾病为慢性阻塞性肺疾病和缺血性心脏病,颗粒物每升高10ìg/m3,相应的住院率上升百分比分别为2.94%、1.94%.非采暖期和采暖期分别分析,非采暖期颗粒物空气污染的影响大于采暖期影响.结论 与有关死亡率研究结果比较,颗粒物空气污染对呼吸系统、心脑血管疾病住院率上升百分比大于死亡率上升百分比(0.25%),表明颗粒物空气污染对住院率的影响大于死亡率.     

Characterization of fine particulate matter and associations between particulate chemical constituents and mortality in Seoul, Korea

Background: Numerous studies have linked fine particles [≤ 2.5 µm in aerodynamic diameter (PM_2.5)] and health. Most studies focused on the total mass of the particles, although the chemical composition of the particles varies substantially. Which chemical components of fine particles that are the most harmful is not well understood, and research on the chemical composition of PM_2.5 and the components that are the most harmful is particularly limited in Asia.Objectives: We characterized PM_2.5 chemical composition and estimated the effects of cause-specific mortality of PM_2.5 mass and constituents in Seoul, Korea. We compared the chemical composition of particles to those of the eastern and western United States.Methods: We examined temporal variability of PM_2.5 mass and its composition using hourly data. We applied an overdispersed Poisson generalized linear model, adjusting for time, day of week, temperature, and relative humidity to investigate the association between risk of mortality and PM_2.5 mass and its constituents in Seoul, Korea, for August 2008 through October 2009.Results: PM_2.5 and chemical components exhibited temporal patterns by time of day and season. The chemical characteristics of Seoul’s PM_2.5 were more similar to PM_2.5 found in the western United States than in the eastern United States. Seoul’s PM_2.5 had lower sulfate (SO₄) contributions and higher nitrate (NO₃) contributions than that of the eastern United States, although overall PM_2.5 levels in Seoul were higher than in the United States. An interquartile range (IQR) increase in magnesium (Mg) (0.05 μg/m³) was associated with a 1.4% increase (95% confidence interval: 0.2%, 2.6%) in total mortality on the following day. Several components that were among the largest contributors to PM_2.5 total mass—NO₃, SO₄, and ammonium (NH₄)—were moderately associated with same-day cardiovascular mortality at the p < 0.10 level. Other components with smaller mass contributions [Mg and chlorine (Cl)] exhibited moderate associations with respiratory mortality on the following day (p < 0.10).Conclusions: Our findings link PM_2.5 constituents with mortality and have implications for policy making on sources of PM_2.5 and on the relevance of PM_2.5 health studies from other areas to this region.     

Saharan dust and associations between particulate matter and daily mortality in Rome, Italy

Background: Outbreaks of Saharan-Sahel dust over Euro-Mediterranean areas frequently induce exceedances of the Europen Union''s 24-hr standard of 50 μg/m³ for particulate matter (PM) with aerodynamic diameter ≤ than 10 μm (PM₁₀).Objectives: We evaluated the effect of Saharan dust on the association between different PM fractions and daily mortality in Rome, Italy.Methods: In a study of 80,423 adult residents who died in Rome between 2001 and 2004, we performed a time-series analysis to explore the effects of PM_2.5, PM_2.5–10, and PM₁₀ on natural, cardiac, cerebrovascular, and respiratory mortality. We defined Saharan dust days by combining light detection and ranging (LIDAR) observations and analyses from operational models. We tested a Saharan dust–PM interaction term to evaluate the hypothesis that the effects of PM, especially coarse PM (PM_2.5–10), on mortality would be enhanced on dust days.Results: Interquartile range increases in PM_2.5–10 (10.8 μg/m³) and PM₁₀ (19.8 μg/m³) were associated with increased mortality due to natural, cardiac, cerebrovascular, and respiratory causes, with estimated effects ranging from 2.64% to 12.65% [95% confidence interval (CI), 1.18–25.42%] for the association between PM_2.5–10 and respiratory mortality (0- to 5-day lag). Associations of PM_2.5–10 with cardiac mortality were stronger on Saharan dust days (9.73%; 95% CI, 4.25–15.49%) than on dust-free days (0.86%; 95% CI, –2.47% to 4.31%; p = 0.005). Saharan dust days also modified associations between PM₁₀ and cardiac mortality (9.55% increase; 95% CI, 3.81–15.61%; vs. dust-free days: 2.09%; 95% CI, –0.76% to 5.02%; p = 0.02).Conclusions: We found evidence of effects of PM_2.5–10 and PM₁₀ on natural and cause-specific mortality, with stronger estimated effects on cardiac mortality during Saharan dust outbreaks. Toxicological and biological effects of particles from desert sources need to be further investigated and taken into account in air quality standards.     

Socioeconomic status, particulate air pollution, and daily mortality: differential exposure or differential susceptibility

BACKGROUND: Short-term increases in particulate air pollution are linked with increased daily mortality and morbidity. Socioeconomic status (SES) is a determinant of overall health. We investigated whether social class is an effect modifier of the PM(10) (particulate matter with diameter <10 micron)-daily mortality association, and possible mechanisms for this effect modification. METHODS: Area-based traffic emissions, income, and SES were available for each resident in Rome. All natural deaths (83,253 subjects) occurring in Rome among city residents (aged 35+ years) during the period 1998-2001 were identified. For each deceased individual, all the previous hospitalizations within 2 years before death were available via a record linkage procedure. PM(10) daily data were available from two urban monitoring sites. A case-crossover analysis was utilized in which control days were selected according to the time stratified approach (same day of the week during the same month). Conditional logistic regression was used. RESULTS: Due to the social class distribution in the city, exposure to traffic emissions was higher among those with higher area-based income and SES. Meanwhile, people of lower social class had suffered to a larger extent from chronic diseases before death than more affluent residents, especially diabetes mellitus, hypertension, heart failure, and chronic obstructive pulmonary diseases. Overall, PM(10) (lag 0-1) was strongly associated with mortality (1.1% increase, 95%CI = 0.7-1.6%, per 10 microg/m(3)). The effect was more pronounced among persons with lower income and SES (1.9% and 1.4% per 10 microg/m(3), respectively) compared to those in the upper income and SES levels (0.0% and 0.1%, respectively). CONCLUSIONS: The results confirm previous suggestions of a stronger effect of particulate air pollution among people in low social class. Given the uneven geographical distributions of social deprivation and traffic emissions in Rome, the most likely explanation is a differential burden of chronic health conditions conferring a greater susceptibility to less advantaged people.     

可吸入大气颗粒物污染与居民每日死亡关系的Meta分析

目的综合分析国内外可吸入大气颗粒物（PM10）短期暴露与人群死亡关系的流行病学资料,以获取大气PM10污染与居民死亡的暴露-反应关系。方法在计算机联机检索文献和手工检索的基础上,对近十年来发表的相关研究文献采用meta分析的方法进行综合评价,并检验、校正可能存在的发表偏倚,从而准确、定量地确定PM10污染与居民死亡的暴露-反应关系。结果建立了居民短期接触大气PM10污染的暴露一反应关系,即在未考虑发表偏倚的情况下,大气中PM10每增加1130μg／m3,居民死亡的相对危险度增加3．87％（95％CI：2．84％～5．02％）,在校正了发表偏倚后大气中PM10每增加100μg／m3,死亡的相对危险度增加下降为1．41％（95％CI：0．30％-2．43％）,与考虑偏倚前相比下降了63．6％。结论本研究建立的暴露-反应关系较早注意到发表偏倚的影响,具有一定的代表性与科学性,可用于大气颗粒物暴露健康危险度评价工作参考,为制定相关环境决策提供科学依据。     

A time-stratified case-crossover study of fine particulate matter air pollution and mortality in Guangzhou, China

Objectives

Few studies in China investigate health impact of fine particulate matter (PM_2.5) due to lack of monitoring data and the findings are controversial. The aim of this study is to examine the short-association between PM_2.5 and daily mortality in Guangzhou, the economic center of south China.

Methods

In Guangzhou, we measured daily PM_2.5 concentrations between 2007 and 2008 and conducted a time-stratified case-crossover analysis to explore the association between PM_2.5 and daily mortality, and examine potential effect modifiers including age, sex, and education.

Results

The averaged PM_2.5 concentration in 2007–2008 was 70.1?μg/m³ in Guangzhou, which was approximately seven times higher than the WHO Air Quality Guidelines for PM_2.5 (annual average: 10?μg/m³). Regression analysis showed that ambient PM_2.5 was associated with mortality from all causes and cardiorespiratory diseases. An increase of 10?μg/m³ in 2-day moving average (lag01) concentration of PM_2.5 corresponds to 0.90% [95% confidence interval (CI): 0.55, 1.26%] increase of total mortality, 1.22% (95% CI: 0.63, 1.68%) increase of cardiovascular mortality, and 0.97% (95% CI: 0.16, 1.79%) increase of respiratory mortality. The associations were stronger in the elderly (aged 65?years or more), in females, and in those with low education level, but the differences were statistically insignificant. After adjustment for nitrogen dioxide (NO₂), however, the effects of PM_2.5 decreased and became statistically insignificant.

Conclusions

Our findings provided new information for the adverse health effects of PM_2.5 in China, and may have some implications for environmental policy making and standard setting in Guangzhou.     

Association of particulate air pollution with daily mortality: the China Air Pollution and Health Effects Study

China is one of the few countries with some of the highest particulate matter levels in the world. However, only a small number of particulate matter health studies have been conducted in China. The study objective was to examine the association of particulate matter with an aerodynamic diameter of less than 10 μm (PM(10)) with daily mortality in 16 Chinese cities between 1996 and 2008. Two-stage Bayesian hierarchical models were applied to obtain city-specific and national average estimates. Poisson regression models incorporating natural spline smoothing functions were used to adjust for long-term and seasonal trends of mortality, as well as other time-varying covariates. The averaged daily concentrations of PM(10) in the 16 Chinese cities ranged from 52 μg/m(3) to 156 μg/m(3). The 16-city combined analysis showed significant associations of PM(10) with mortality: A 10-μg/m(3) increase in 2-day moving-average PM(10) was associated with a 0.35% (95% posterior interval (PI): 0.18, 0.52) increase of total mortality, 0.44% (95% PI: 0.23, 0.64) increase of cardiovascular mortality, and 0.56% (95% PI: 0.31, 0.81) increase of respiratory mortality. Females, older people, and residents with low educational attainment appeared to be more vulnerable to PM(10) exposure. Conclusively, this largest epidemiologic study of particulate air pollution in China suggests that short-term exposure to PM(10) is associated with increased mortality risk.     

Wildfire air pollution and daily mortality in a large urban area

Unusual air pollution episodes, such as when smoke from wildfires covers a large urban area, can be used to attempt to detect associations between short-term increases in particulate matter (PM) concentrations and subsequent mortality without relying on the sophisticated statistical models that are typically required in the absence of such episodes. The objective of this study was to explore whether acute increases in PM concentrations from wildfire smoke cause acute increases in daily mortality. The temporal patterns of daily nonaccidental deaths and daily cardiorespiratory deaths for June of 2002 in the Denver metropolitan area were examined and compared to those in two nearby counties in Colorado that were not affected by the wildfire smoke and to daily deaths in Denver in June of 2001. Abrupt increases in PM concentrations in Denver occurred on 2 days in June of 2002 as a result of wildfire smoke drifting over the Denver area. Small peaks in mortality corresponded to both of the PM peaks, but the first mortality peak also corresponded to a peak of mortality in the control counties, and cardiorespiratory deaths began to increase on the day before the second peak. Further, there was no detectable increase in cardiorespiratory deaths in the hours immediately following the PM peaks. Although the findings from this study do not rule out the possibility of small increases in mortality due to abrupt and dramatic increases in PM concentrations from wildfire smoke, in a population of over 2 million people no perceptible increases in daily mortality could be attributed to such events.     

Fine particulate air pollution and mortality in nine California counties: results from CALFINE

Many epidemiologic studies provide evidence of an association between daily counts of mortality and ambient particulate matter<10 microm in diameter (PM10). Relatively few studies, however, have investigated the relationship of mortality with fine particles [PM<2.5 microm in diameter (PM2.5)], especially in a multicity setting. We examined associations between PM2.5 and daily mortality in nine heavily populated California counties using data from 1999 through 2002. We considered daily counts of all-cause mortality and several cause-specific subcategories (respiratory, cardiovascular, ischemic heart disease, and diabetes). We also examined these associations among several subpopulations, including the elderly (>65 years of age), males, females, non-high school graduates, whites, and Hispanics. We used Poisson multiple regression models incorporating natural or penalized splines to control for covariates that could affect daily counts of mortality, including time, seasonality, temperature, humidity, and day of the week. We used meta-analyses using random-effects models to pool the observations in all nine counties. The analysis revealed associations of PM2.5 levels with several mortality categories. Specifically, a 10-microg/m3 change in 2-day average PM2.5 concentration corresponded to a 0.6% (95% confidence interval, 0.2-1.0%) increase in all-cause mortality, with similar or greater effect estimates for several other subpopulations and mortality subcategories, including respiratory disease, cardiovascular disease, diabetes, age>65 years, females, deaths out of the hospital, and non-high school graduates. Results were generally insensitive to model specification and the type of spline model used. This analysis adds to the growing body of evidence linking PM2.5 with daily mortality.     

Particulate air pollution and daily mortality in Detroit.

Particulate air pollution has been associated with increased mortality during episodes of high pollution concentrations. The relationship at lower concentrations has been more controversial, as has the relative role of particles and sulfur dioxide. Replication has been difficult because suspended particle concentrations are usually measured only every sixth day in the U.S. This study used concurrent measurements of total suspended particulates (TSP) and airport visibility from every sixth day sampling for 10 years to fit a predictive model for TSP. Predicted daily TSP concentrations were then correlated with daily mortality counts in Poisson regression models controlling for season, weather, time trends, overdispersion, and serial correlation. A significant correlation (P less than 0.0001) was found between predicted TSP and daily mortality. This correlation was independent of sulfur dioxide, but not vice versa. The magnitude of the effect was very similar to results recently reported from Steubenville, Ohio (using actual TSP measurements), with each 100 micrograms/m3 increase in TSP resulting in a 6% increase in mortality. Graphical analysis indicated a dose-response relationship with no evidence of a threshold down to concentrations below half of the National Ambient Air Quality Standards for particulate matter.