Particulates in domestic premises. II. Ambient levels and indoor-outdoor relationships.

Three indoor environments, two residential and on institutional, were monitored for particulate and gaseous air pollutants over a one-year period. Inside air particulate levels decreased at night and under conditions of no household activity. Different homes showed different time lags in correlating inside vs outside particle counts. Indoor particle count reduction correlated to rate of air flow through the precipitator. The standard, portable household vacuum cleaner produced about a 100% increase in counts of particles measuring 1.0 mum and larger, as compared to a 50% increase produced by the central vacuum system. Particulates that were smaller than 1.0 mum were not substantially affected by smoking. The indoor gaseous pollutants showed very low maximum levels.     

Indoor particle counts during Asian dust events under everyday conditions at an apartment in Japan

Objective

Asian dust storms originating from arid regions of Mongolia and China are a well-known springtime phenomenon throughout East Asia. Evidence is increasing for the adverse health effects caused by airborne desert dust inhalation. Given that people spend approximately 90 % of their time indoors, indoor air quality is a significant concern. The present study aimed to examine the influence of outdoor particulate matter (PM) levels on indoor PM levels during Asian dust events under everyday conditions.

Methods

We simultaneously monitored counts of particles larger than 0.3, 0.5, 1, 2, and 5 μm using two direct-reading instruments (KC-01D1 airborne particle counter; Rion), one placed in an apartment room and another on the veranda, under everyday conditions before and during an Asian dust event. We also examined how indoor particle counts were affected by opening a window, crawling, and air purifier use.

Results

An Asian dust event on 24 April 2012 caused 50- and 20-fold increases in PM counts in outdoor and indoor air, respectively. A window open for 10 min resulted in a rapid increase of indoor PM counts up to 70 % of outside levels that did not return to baseline levels after 3 h. An air purifier rapidly reduced PM counts for all particle sizes measured.

Conclusions

It is important to account for occupant behavior, such as window-opening and air purifier use, when estimating residential exposure to particulate matter.     

Is the association of airborne particles with daily deaths confounded by gaseous air pollutants? An approach to control by matching.

Although particulate air pollution has been associated with increased numbers of daily deaths in dozens of cities around the world, issues still remain about the association. Some have questioned the complex modeling used to control for season in Poisson regression or the role of gaseous air pollutants as potential confounders of the association. I examined the association between deaths and particulate matter with an aerodynamic diameter less than or equal to 10 microm (PM10) using a case-crossover design. In this approach, the pollution on the day of each death is contrasted with the pollution level on control days when the subject did not die. Season and gaseous air pollutants were controlled by matching. Control days were chosen within the same month of the same year to control for season, and matched on either sulfur dioxide (SO2; within 1 ppb), nitrogen dioxide (within 1 ppb), maximum ozone (within 2 ppb), or carbon monoxide (within 0.03 ppm). The analysis was conducted in 14 U.S. cities that have daily PM10 monitoring. After matching, there were about 400,000 deaths in each analysis. Results were combined across cities using a maximum likelihood method. PM10 was a significant predictor of mortality when controlling for gaseous air pollutants, with effect sizes ranging from a 0.45% increase per 10 microg/m3 increment of PM10 [95% confidence interval (CI), 0.12-0.79%] when matched on maximum hourly ozone levels, to a 0.81% increase per 10 microg/m3 increment of PM10 (95% CI, 0.47-1.16%) when matched on 24-hr average SO2.     

The role of particulate size and chemistry in the association between summertime ambient air pollution and hospitalization for cardiorespiratory diseases.

In order to address the role that the ambient air pollution mix, comprised of gaseous pollutants and various physical and chemical measures of particulate matter, plays in exacerbating cardiorespiratory disease, daily measures of fine and coarse particulate mass, aerosol chemistry (sulfates and acidity), and gaseous pollution (ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide) were collected in Toronto, Ontario, Canada, in the summers of 1992, 1993, and 1994. These time series were then compared with concurrent data on the number of daily admissions to hospitals for either cardiac diseases (ischemic heart disease, heart failure, and dysthymias) or respiratory diseases (tracheobronchitis, chronic obstructive long disease, asthma, and pneumonia). After adjusting the admission time series for long-term temporal trends, seasonal variations, the effects of short-term epidemics, day of the week effects, and ambient temperature and dew point temperature, positive associations were observed for all ambient air pollutants for both respiratory and cardiac diseases. Ozone was least sensitive to adjustment for the gaseous and particulate pollution measures. However, the association between the health outcomes and carbon monoxide, fine and coarse mass, sulfate levels and aerosol acidity could be explained by adjustment for exposure to gaseous pollutants. Increases in ozone, nitrogen dioxide, and sulfur dioxide equivalent to their interquartile ranges corresponded to an 11% and 13% increase in daily hospitalizations for respiratory and cardiac diseases, respectively. The inclusion of any one of the particulate air pollutants in multiple regression models did not increase these percentages. Particle mass and chemistry could not be identified as an independent risk factor for the exacerbation of cardiorespiratory diseases in this study beyond that attributable to climate and gaseous air pollution. We recommend that effects of particulate matter on health be assessed in conjunction with temporally covarying gaseous air pollutants.     

Particle resuspension during the use of vacuum cleaners on residential carpet

Vacuuming is generally considered to be an important activity with respect to the cleanliness of indoor environments but may lead to short-term resuspension of particulate matter and elevated particle mass in indoor air. Because resuspended particles often contain toxicants, such as lead and pesticides, or consist of biological agents that can trigger allergic reactions, it is important to understand the role of vacuuming on short-term variations in indoor particulate matter concentrations. The inhalation of particles during vacuuming events may affect adversely those whose occupation requires them to clean a wide range of indoor environments, from homes to schools and offices, as well as those who occupy those environments. In response, a series of 46 experiments was completed to determine time-variant concentrations of both PM(10) and PM(2.5) during various vacuuming activities in 12 separate apartments. Experiments involved the use of two different non-HEPA vacuum cleaners and were completed with a vacuum cleaner activated (switched on) as well as deactivated (switched off). The latter was intended to provide insight on the potential for resuspension of particles by the mechanical agitation of vacuum cleaner movement across carpet. Separate experiments were completed also using "mock" vacuuming simulations, that is, walking on the carpet in a manner consistent with using a vacuum cleaner. Results are presented as incremental particulate matter concentration increases, relative to background (prevacuum) concentrations, and peak-to-background particle concentration ratios. Results indicate significant resuspension of PM(10) mass during vacuum cleaning, with a mean time-averaged PM(10) increase of greater than 17 mu g/m(3) above background. Resuspension of PM(2.5) mass was determined to be small, that is, PM(10) mass was dominated by particles greater than 2.5 mu m. The frequency of vacuuming (between a 10-day standard frequency and several experiments at > 24 days between vacuuming) had little influence on resuspended particle mass. Resuspension by mechanical agitation (rolling of vacuum cleaner across carpet) with the vacuum cleaner switched off was determined to be substantial, with a mean time-averaged (during vacuuming) PM(10) increase of 35 mu g/m(3) relative to background. Peak-to-background PM(10) concentrations exceeded 6 for some experiments and averaged between approximately 3 and 4 for experiments when the vacuum cleaner was switched on.     

Respirable particles and carcinogens in the air of delaware hospitality venues before and after a smoking ban

How do the concentrations of indoor air pollutants known to increase risk of respiratory disease, cancer, heart disease, and stroke change after a smoke-free workplace law? Real-time measurements were made of respirable particle (RSP) air pollution and particulate polycyclic aromatic hydrocarbons (PPAH), in a casino, six bars, and a pool hall before and after a smoking ban. Secondhand smoke contributed 90% to 95% of the RSP air pollution during smoking, and 85% to 95% of the carcinogenic PPAH, greatly exceeding levels of these contaminants encountered on major truck highways and polluted city streets. This air-quality survey demonstrates conclusively that the health of hospitality workers and patrons is endangered by tobacco smoke pollution. Smoke-free workplace laws eliminate that hazard and provide health protection impossible to achieve through ventilation or air cleaning.     

Air pollution and daily mortality in Shanghai: a time-series study

In this study, the authors assessed the relationship between air pollution and daily mortality from June 2000 to December 2001 in Shanghai, the largest city in China. They used the generalized additive model to allow for the highly flexible long-term and seasonable trends, and for nonlinear weather variables. In the single-pollutant models, the authors found significant associations between concentrations of air pollutants (particulate matter less than 10 microm in aerodynamic diameter [PM10], sulfur dioxide [SO2], and nitrogen dioxide [NO2]) and daily mortality. An increase of 10 microg/m3 in PM10, SO2, and NO2 corresponded to a respective increase in relative risk of mortality from all causes of 1.003 (95% confidence interval [CI] = 1.001, 1.005), 1.014 (95% CI = 1.008, 1.020), and 1.015 (95% CI = 1.008, 1.022). In the multiple-pollutant models, the association between SO2 and daily mortality was not affected by the inclusion of other pollutants; for PM10 and NO2, however, the inclusion of other pollutants possibly weakened the effects between these 2 pollutants and mortality. This finding suggests that gaseous pollutants may be more important than particulate matter as indicators of health in Shanghai. The authors' analyses provided evidence that the current amounts of air pollution in Shanghai continue to adversely affect population health, and strengthen the rationale for limiting the quantities of pollutants in outdoor air.     

Particulate matter, DNA methylation in nitric oxide synthase, and childhood respiratory disease

Background: Air pollutants have been associated with childhood asthma and wheeze. Epigenetic regulation of nitric oxide synthase-the gene responsible for nitric oxide production-may be affected by air pollutants and contribute to the pathogenesis of asthma and wheeze.Objective: Our goal was to investigate the association between air pollutants, DNA methylation, and respiratory outcomes in children.Methods: Given residential address and buccal sample collection date, we estimated 7-day, 1-month, 6-month, and 1-year cumulative average PM2.5 and PM10 (particulate matter ≤ 2.5 and ≤ 10 μm aerodynamic diameter, respectively) exposures for 940 participants in the Children's Health Study. Methylation of 12 CpG sites in three NOS (nitric oxide synthase) genes was measured using a bisulfite-polymerase chain reaction Pyrosequencing assay. Beta regression models were used to estimate associations between air pollutants, percent DNA methylation, and respiratory outcomes.Results: A 5-μg/m3 increase in PM2.5 was associated with a 0.20% [95% confidence interval (CI): -0.32, -0.07] to 1.0% (95% CI: -1.61, -0.56) lower DNA methylation at NOS2A position 1, 0.06% (95% CI: -0.18, 0.06) to 0.58% (95% CI: -1.13, -0.02) lower methylation at position 2, and 0.34% (95% CI: -0.57, -0.11) to 0.89% (95% CI: -1.57, -0.21) lower methylation at position 3, depending on the length of exposure and CpG locus. One-year PM2.5 exposure was associated with 0.33% (95% CI: 0.01, 0.65) higher in average DNA methylation of 4 loci in the NOS2A CpG island. A 5-μg/m3 increase in 7-day and 1-year PM2.5 was associated with 0.6% (95% CI: 0.13, 0.99) and 2.8% (95% CI: 1.77, 3.75) higher NOS3 DNA methylation. No associations were observed for NOS1. PM10 showed similar but weaker associations with DNA methylation in these genes.Conclusions: PM2.5 exposure was associated with percent DNA methylation of several CpG loci in NOS genes, suggesting an epigenetic mechanism through which these pollutants may alter production of nitric oxide.     

Particulate matter and polycyclic aromatic hydrocarbon concentrations in indoor and outdoor microenvironments in Boston, Massachusetts

Estimating personal exposures to air pollution is a crucial component in identifying high-risk populations and determining efficient control strategies. Because of the difficulty of comprehensively measuring personal exposure, data on air pollution patterns in homogenous microenvironments linked with activity data are often used as surrogates. In this study, we focus on strengthening the available information about nonresidential microenvironmental exposures to particulate matter and other combustion pollutants. During the summer of 2000, we measured ultrafine particles, fine particulate matter (PM2.5), and particle-bound polycyclic aromatic hydrocarbons (PAHs) outdoors and in indoor microenvironments in Boston, Massachusetts. In indoor microenvironments averaged across sample days, mean ultrafine particle concentrations ranged from 3800 to 140,000 particles/cm(3), with 7-200 microg/m(3) of PM2.5 and 5-12 ng/m(3) of particle-bound PAH. PM2.5 indoor-outdoor ratios generally exceeded 1 in settings with high levels of human activity, with lower ratios for ultrafine particles. Cooking activities contributed significantly to elevated levels of all three pollutants. Using Linear Mixed Effects models with AR-1 autoregressive correlation structures, 10-min average outdoor concentrations were generally weak predictors of indoor levels, with stronger relationships in an apartment without mechanical ventilation than in air-conditioned nonresidential settings. Although further study would be needed to determine whether these patterns could be generalized beyond the monitored sites, these data support previous findings and enhance our knowledge about nonresidential exposure patterns.     

Indoor air quality in urban and rural kindergartens: short-term studies in Silesia,Poland

More than 80% of people living in urban areas who monitor air pollution are exposed to air quality levels that exceed limits defined by the World Health Organization (WHO). Although all regions of the world are affected, populations in low-income cities are the most impacted. According to average annual levels of fine particulate matter (PM2.5, ambient particles with aerodynamic diameter of 2.5 μm or less) presented in the urban air quality database issued by WHO in 2016, as many as 33 Polish cities are among the 50 most polluted cities in the European Union (EU), with Silesian cities topping the list. The aim of this study was to characterize the indoor air quality in Silesian kindergartens based on the concentrations of gaseous compounds (SO₂, NO₂), PM2.5, and the sum of 15 PM2.5-bound polycyclic aromatic hydrocarbons (PAHs), including PM2.5-bound benzo(a)pyrene (BaP), as well as the mutagenic activity of PM2.5 organic extracts in Salmonella assay (strains: TA98, YG1024). The assessment of the indoor air quality was performed taking into consideration the pollution of the atmospheric air (outdoor). I/O ratios (indoor/outdoor concentration) for each investigated parameter were also calculated. Twenty-four-hour samples of PM2.5, SO₂, and NO₂ were collected during spring in two sites in southern Poland (Silesia), representing urban and rural areas. Indoor samples were taken in naturally ventilated kindergartens. At the same time, in the vicinity of the kindergarten buildings, the collection of outdoor samples of PM2.5, SO₂, and NO₂ was carried out. The content of BaP and the sum of 15 studied PAHs was determined in each 24-h sample of PM2.5 (indoor and outdoor). In the urban site, statistically lower concentrations of SO₂ and NO₂ were detected indoors compared to outdoors, whereas in the rural site, such a relationship was observed only for NO₂. No statistically significant differences in the concentrations of PM2.5, PM2.5-bound BaP, and Σ15 PAHs in kindergartens (indoor) versus atmospheric (outdoor) air in the two studied areas were identified. Mutagenic effect of indoor PM2.5 samples was twice as low as in outdoor samples. The I/O ratios indicated that all studied air pollutants in the urban kindergarten originated from the ambient air. In the rural site concentrations of SO₂, PM2.5 and BaP in the kindergarten were influenced by internal sources (gas and coal stoves).     

Air pollution and incidence of cardiac arrhythmia

Air pollution episodes have been associated with increased cardiovascular hospital admissions and mortality in time-series studies. We tested the hypothesis that patients with implanted cardioverter defibrillators experience potentially life-threatening arrhythmias after such air pollution episodes. We compared defibrillator discharge interventions among 100 patients with such devices in eastern Massachusetts, according to variations in concentrations of particulate matter, black carbon, and gaseous air pollutants that were measured daily for the years 1995 through 1997. A 26-ppb increase in nitrogen dioxide was associated with increased defibrillator interventions 2 days later (odds ratio = 1.8; 95% confidence interval = 1.1-2.9). Patients with ten or more interventions experienced increased arrhythmias in association with nitrogen dioxide, carbon monoxide, black carbon, and fine particle mass. These results suggest that elevated levels air pollutants are associated with potentially life-threatening arrhythmia leading to therapeutic interventions by an implanted cardioverter defibrillator.     

石家庄市气态污染物与每日居民死亡人数的时间序列分析

目的 探讨石家庄市大气气态污染物SO2、NO2、O3-8 h和CO浓度与居民每日死亡人数之间的关系.方法 收集石家庄市2013—2016年每日死亡人数、大气污染物浓度、气象资料,采用广义相加时间序列模型,分析气态污染物浓度对死亡的影响,并按照性别、年龄进行分层分析.结果 大气SO2浓度每增加10μg/m3,人群非意外总...     

Characterization of indoor particle sources: A study conducted in the metropolitan Boston area

An intensive particle monitoring study was conducted in homes in the Boston, Massachusetts, area during the winter and summer of 1996 in an effort to characterize sources of indoor particles. As part of this study, continuous particle size and mass concentration data were collected in four single-family homes, with each home monitored for one or two 6-day periods. Additionally, housing activity and air exchange rate data were collected. Cooking, cleaning, and the movement of people were identified as the most important indoor particle sources in these homes. These sources contributed significantly both to indoor concentrations (indoor-outdoor ratios varied between 2 and 33) and to altered indoor particle size distributions. Cooking, including broiling/baking, toasting, and barbecuing contributed primarily to particulate matter with physical diameters between 0.02 and 0.5 microm [PM((0.02-0.5))], with volume median diameters of between 0.13 and 0.25 microm. Sources of particulate matter with aerodynamic diameters between 0.7 and 10 microm [PM((0.7-10))] included sautéing, cleaning (vacuuming, dusting, and sweeping), and movement of people, with volume median diameters of between 3 and 4.3 microm. Frying was associated with particles from both PM((0.02-0.5)) and PM((0.7-10)). Air exchange rates ranged between 0.12 and 24.3 exchanges/hr and had significant impact on indoor particle levels and size distributions. Low air exchange rates (< 1 exchange/hr) resulted in longer air residence times and more time for particle concentrations from indoor sources to increase. When air exchange rates were higher (> 1 exchange/hr), the impact of indoor sources was less pronounced, as indoor particle concentrations tracked outdoor levels more closely.     

北京一次空气重污染过程室内外微生物气溶胶的浓度变化及影响因素分析

目的 分析北京一次空气重污染黄色预警期间室内外微生物气溶胶的浓度和粒径变化特征及相关影响因素。方法 采用Andersen空气微生物采样器在北京市空气重污染黄色预警期间对室内外环境进行采样、培养,同时记录采样时的环境因素、颗粒物以及气态污染物的浓度。结果 在本次北京市空气重污染期间室外细菌和真菌气溶胶浓度显著高于室内细菌和真菌气溶胶浓度(P<0.01),室内外细菌和真菌浓度变化趋势具有显著正相关(P<0.01),发现63.62%~96.70%的细菌或真菌气溶胶粒子直径小于5μm,Spearman相关分析表明室外细菌气溶胶浓度与温度具有显著正相关(P<0.01),与相对湿度具有显著负相关(P<0.01),室内细菌气溶胶浓度与温度和相对湿度具有显著正相关(P<0.01),室外真菌气溶胶浓度与SO2、PM10、PM2.5和AQI指数具有显著正相关(P<0.01),与相对湿度具有显著负相关,室内真菌气溶胶浓度与温度、SO2、PM10、PM2.5和AQI指数具有显著正相关(P<0.01),与O3浓度具有显著负相关(P<0.01)。结论 本次空气重污染预警期间,室外微生物气溶胶浓度显著高于室内,超过60%的室外或室内微生物气溶胶粒子直径小于5μm,室内外微生物气溶胶浓度受多个环境因素参数影响。     

9种住宅空气净化器的净化效果

[目的]评价目前市场上主要品牌住宅用空气净化器对空气污染物的净化效果。[方法]采用30m3环境测试舱法测试9种家用空气净化器对颗粒物、甲醛、总挥发性有机化合物（TVOC）、氨、二甲苯的净化效果,并以去除率、洁净空气量、净化效能等指标评价上述空气净化器的净化性能。[结果]在所测试的净化器中,对甲醛、TVOC、氨、二甲苯的3h去除率≥80％的净化器分别占测试总数的55．6％、88．9％、33．3％和88．9％。按甲醛、TVOC、氨、二甲苯净化效能符合《空气净化器》（GB／T18801-2008）（≥D级）要求划分的净化器分别占测试总数的77．7％、88．9％、55．6％和100．0％;颗粒物净化效能符合《空气净化器》净化效能A级要求的空气净化器占测试总数的88．9％。[结论]所抽检的家用空气净化器有机污染气体和颗粒物净化的总体性能良好,而对氨类的净化性能不足。     

宣威室内空气污染物的鉴定及个体接触浓度

宣威县是农村肺癌高发区。流行病学调查、毒理学实验、环境污染物的监测等研究已表明肺癌高发的原因与燃煤造成的空气污染有关。为进一步证实这一病因学说,我们对肺癌死亡率高的乡选代表性住户对不同性别的居民进行了个体接触污染物浓度的监测。同时选死亡率低的乡进行对照。监测的项目有:一氧化碳、二氧化硫、氧化氮、甲醛、挥发性有机物、气相及固相多环芳烃及多种无机元素;同时也观察了颗粒物的粒度分布及粒子的外形。结果表明,多环芳烃仍为癌症的主要原因。     

Associations between ambient air pollution and daily mortality among persons with congestive heart failure

We conducted a mortality time series study to investigate the association between daily mortality for congestive heart failure (CHF), and daily concentrations of particles and gaseous pollutants in the ambient air of Montreal, Quebec, during the period 1984-1993. In addition, using data from the universal Quebec Health Insurance Plan, we identified individuals >/=65 years of age who, one year before death, had a diagnosis of CHF. Fixed-site air pollution monitors in Montreal provided daily mean levels of pollutants. We regressed the logarithm of daily counts of mortality on the daily mean levels of each pollutant, after accounting for seasonal and subseasonal fluctuations in the mortality time series, non-Poisson dispersion, weather variables, and other gaseous and particle pollutants. Using cause of death information, we did not find any associations between daily mortality for CHF and any air pollutants. The analyses of CHF defined from the medical record showed positive associations with coefficient of haze, the extinction coefficient, SO(2), and NO(2). For example, the mean percent increase in daily mortality for an increase in the coefficient of haze across the interquartile range was 4.32% (95% CI: 0.95-7.80%) and for NO(2) it was 4.08% (95% CI: 0.59-7.68%). These effects were generally higher in the warm season.     

Customers' exposure to PM2.5 and polycyclic aromatic hydrocarbons in smoking/nonsmoking sections of 24-h coffee shops in Taiwan

In Taiwan 24-h coffee shops have become popular gathering areas for young people. This study assesses customers' exposures to PM(2.5) and gaseous/particulate polycyclic aromatic hydrocarbons (PAHs) in such an environment. Potential influential factors were also evaluated. Two coffee shops with different types of smoking/nonsmoking divisions were selected. Sampling was conducted from 1300 to 2100 hours on Saturdays and Sundays during December 2000 and January 2001. Personal environmental monitors mounted with Teflon filters and polyurethane foams were used for particulate and gaseous sampling. PAHs were analyzed with GC-FID. Principal component analysis was used to explore the differences in the patterns of gaseous and particulate PAHs. Stepwise regression analysis was used to evaluate the contribution of various factors. The geometric mean (GM) of PM(2.5), particulate and gaseous PAH exposures were 83.7, 0.46 and 1.01 microg/m(3), respectively. Their exposure concentrations were about two to five times those of residential indoor environments in Taiwan. Smoking and vehicle exhaust were two major exposure sources. The gaseous PAH concentrations in the two sections of both shops were significantly correlated. The divisions between smoking and nonsmoking sections in neither of the coffee shops were effective to prevent dispersion of gaseous pollutants. In both shops, the concentrations of PM(2.5) and associated PAHs, respectively, were about 22-28 microg/m(3) and 0.07 microg/m(3) higher in smoking areas compared to nonsmoking areas. It was also found that each additional cigarette resulted in a 0.22-0.42 microg/m(3) PM(2.5) incremental increase in nonsmoking customers' exposure in the smoking section.     

Effects of air pollutants on acute stroke mortality

The relationship between stroke and air pollution has not been adequately studied. We conducted a time-series study to examine the evidence of an association between air pollutants and stroke over 4 years (January 1995-December 1998) in Seoul, Korea. We used a generalized additive model to regress daily stroke death counts for each pollutant, controlling for seasonal and long-term trends and meteorologic influences, such as temperature, relative humidity, and barometric pressure. We observed an estimated increase of 1.5% [95% confidence interval (CI), 1.3-1.8%] and 2.9% (95% CI, 0.3-5.5%) in stroke mortality for each interquartile range increase in particulate matter < 10 microm aerodynamic diameter (PM(10)) and ozone concentrations in the same day. Stroke mortality also increased 3.1% (95% CI, 1.1-5.1%) for nitrogen dioxide, 2.9% (95% CI, 0.8-5.0%) for sulfur dioxide, and 4.1% (95% CI, 1.1-7.2%) for carbon monoxide in a 2-day lag for each interquartile range increase in single-pollutant models. When we examined the associations among PM(10) levels stratified by the level of gaseous pollutants and vice versa, we found that these pollutants are interactive with respect to their effects on the risk of stroke mortality. We also observed that the effects of PM(10) on stroke mortality differ significantly in subgroups by age and sex. We conclude that PM(10) and gaseous pollutants are significant risk factors for acute stroke death and that the elderly and women are more susceptible to the effect of particulate pollutants.     

Ambient air pollution and respiratory emergency department visits

BACKGROUND: A number of emergency department studies have corroborated findings from mortality and hospital admission studies regarding an association of ambient air pollution and respiratory outcomes. More refined assessment has been limited by study size and available air quality data. METHODS: Measurements of 5 pollutants (particulate matter [PM10], ozone, nitrogen dioxide [NO2], carbon monoxide [CO], and sulfur dioxide [SO2]) were available for the entire study period (1 January 1993 to 31 August 2000); detailed measurements of particulate matter were available for 25 months. We obtained data on 4 million emergency department visits from 31 hospitals in Atlanta. Visits for asthma, chronic obstructive pulmonary disease, upper respiratory infection, and pneumonia were assessed in relation to air pollutants using Poisson generalized estimating equations. RESULTS: In single-pollutant models examining 3-day moving averages of pollutants (lags 0, 1, and 2): standard deviation increases of ozone, NO2, CO, and PM10 were associated with 1-3% increases in URI visits; a 2 microg/m increase of PM2.5 organic carbon was associated with a 3% increase in pneumonia visits; and standard deviation increases of NO2 and CO were associated with 2-3% increases in chronic obstructive pulmonary disease visits. Positive associations persisted beyond 3 days for several of the outcomes, and over a week for asthma. CONCLUSIONS: The results of this study contribute to the evidence of an association of several correlated gaseous and particulate pollutants, including ozone, NO2, CO, PM, and organic carbon, with specific respiratory conditions.