Ambient air pollution and birth weight in full-term infants in Atlanta, 1994-2004

Background

An emerging body of evidence suggests that ambient levels of air pollution during pregnancy are associated with fetal growth.

Objectives

We examined relationships between birth weight and temporal variation in ambient levels of carbon monoxide, nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone, particulate matter ≤ 10 μm in diameter (PM₁₀), ≤ 2.5 μm (PM_2.5), 2.5 to 10 μm (PM_2.5–10), and PM_2.5 chemical component measurements for 406,627 full-term births occurring between 1994 and 2004 in five central counties of metropolitan Atlanta.

Methods

We assessed relationships between birth weight and pollutant concentrations during each infant’s first month of gestation and third trimester, as well as in each month of pregnancy using distributed lag models. We also conducted capture-area analyses limited to mothers residing within 4 miles (6.4 km) of each air quality monitoring station.

Results

In the five-county analysis, ambient levels of NO₂, SO₂, PM_2.5 elemental carbon, and PM_2.5 water-soluble metals during the third trimester were significantly associated with small reductions in birth weight (−4 to −16 g per interquartile range increase in pollutant concentrations). Third-trimester estimates were generally higher in Hispanic and non-Hispanic black infants relative to non-Hispanic white infants. Distributed lag models were also suggestive of associations between air pollutant concentrations in late pregnancy and reduced birth weight. The capture-area analyses provided little support for the associations observed in the five-county analysis.

Conclusions

Results provide some support for an effect of ambient air pollution in late pregnancy on birth weight in full-term infants.     

Ambient Air Pollution and Daily Outpatient Visits for Cardiac Arrhythmia in Shanghai,China

Background

Cardiac arrhythmias are cardiac rhythm disorders that comprise an important public health problem. Few prior studies have examined the association between ambient air pollution and arrhythmias in general populations in mainland China.

Methods

We performed a time-series analysis to investigate the short-term association between air pollution (particulate matter with an aerodynamic diameter less than 10 µm [PM₁₀], sulfur dioxide [SO₂], and nitrogen dioxide [NO₂]) and outpatient visits for arrhythmia in Shanghai, China. We applied the over-dispersed Poisson generalized additive model to analyze the associations after control for seasonality, day of the week, and weather conditions. We then stratified the analyses by age, gender, and season.

Results

We identified a total of 56 940 outpatient visits for cardiac arrhythmia. A 10-µg/m³ increase in the present-day concentrations of PM₁₀, SO₂, and NO₂ corresponded to increases of 0.56% (95% CI 0.42%, 0.70%), 2.07% (95% CI 1.49%, 2.64%), and 2.90% (95% CI 2.53%, 3.27%), respectively, in outpatient arrhythmia visits. The associations were stronger in older people (aged ≥65 years) and in females. This study provides the first evidence that ambient air pollution is significantly associated with increased risk of cardiac arrhythmia in mainland China.

Conclusions

Our analyses provide evidence that the current air pollution levels have an adverse effect on cardiovascular health and strengthened the rationale for further limiting air pollution levels in the city.Key words: air pollution, outpatient visits, cardiac arrhythmias, time-series     

Ambient ozone concentration and hospital admissions due to childhood respiratory diseases in New York State, 1991-2001

Background and objective

Respiratory diseases constitute one of the leading causes of ill health among children in New York State (NYS). The current project, a component of the NYS Environmental Public Health Tracking Program, investigated a potential association between ambient ozone (O₃) concentration and childhood respiratory hospital admissions over 11 years in NYS.

Methods

We used a two-stage Bayesian hierarchical model to assess the exposure-disease associations within 11 geographic regions and statewide. The data included total daily hospital admissions due to respiratory diseases for children 0-17 years old from 1991 to 2001 in NYS (N=134,099) and daily ambient O₃ level with different single-day lags. These analyses adjusted for particulate matter ?10 μm in size (PM₁₀), meteorological conditions, day of the week, seasonality, long-term trends, and demographic characteristics.

Results

In 5 of the 11 regions, including the Upper and Lower Adirondacks, Upper Hudson Valley, Staten Island, and New York City, positive associations were found between respiratory hospital admissions and ambient O₃ level 2 days prior to the admission. Applying different statistical methods and sensitivity analysis of PM₁₀ did not alter these findings. When region-specific results were combined, no statewide association was apparent.

Conclusions

Geographic differences were found in the associations between O₃ levels and respiratory hospital admissions among children. In addition, we found that the two-stage model may be an appropriate approach for tracking the health effects of air pollution over time in different geographic areas when heterogeneity of risk factors across regions is present.     

Does area level socioeconomic status modify the effects of PM10 on preterm delivery?

Background

Air pollution has been one of the focal points for investigations of maternal health and birth, and an association has been found between air pollution and birth outcomes. Some individual-level risk factors of mothers have been identified as strong predictors of preterm delivery (PTD). Recent literature has shown that the neighborhood environment of the mother and child has an independent influence on birth outcomes that was not explained by individual-level risk factors.

Objective

This study explored the effects of maternal exposure to particulate air pollution (PM₁₀) and its relationship to the probability of preterm delivery (PTD) in Seoul, Korea. Our hypothesis was that PM₁₀ increased the probability of PTD, and that the area level socioeconomic status (SES), measured by monthly average household income, modified the PM₁₀ effects on PTD after controlling for individual-level risk factors such as individual-level SES.

Data and Method

Birth data from the Korean National Statistics Office consisted of records on 433,173 singleton births in the years 2000-2003, and included individual characteristics. Area-level characteristics were also controlled for in 25 administrative regions in Seoul. Maternal exposure to PM₁₀ was calculated at an individual level for each trimester using information from monitoring sites in residential areas. Hourly data on PM₁₀ for 1999-2003 were acquired from the National Institute of Environment Research. Birth outcome was dichotomously coded: term birth (gestation ≥37 weeks) or PTD (gestation <37 weeks). For multilevel analysis, we conducted a hierarchical logistic regression with a random intercept for each administrative area to account for the hierarchical nature of the data.

Results

We found that area-level SES modified the PM₁₀ effects on PTD, specifically among those who were in low SES areas. Results of multilevel analyses showed that an increase in PM₁₀ by 10 μg/m³ led to a statistically significant increase in the probability of PTD [3.12% (95% CI, 0.17-6.15)] during the 2nd trimester in the low-income group. Analyses using the stratified population found a 3.4% increase (95% CI, 0.31-6.58) in the probability of PTD during the 2nd trimester in areas with low income.

Conclusion

Mothers exposed to higher PM₁₀ in Seoul, Korea, had a higher probability of PTD. Individual-level characteristics had different effects on the probability of PTD depending on the area-level SES. Area-level SES modified the effect of PM₁₀ concentration on PTD.     

Effect of Early Life Exposure to Air Pollution on Development of Childhood Asthma

Background

There is increasing recognition of the importance of early environmental exposures in the development of childhood asthma. Outdoor air pollution is a recognized asthma trigger, but it is unclear whether exposure influences incident disease. We investigated the effect of exposure to ambient air pollution in utero and during the first year of life on risk of subsequent asthma diagnosis in a population-based nested case–control study.

Methods

We assessed all children born in southwestern British Columbia in 1999 and 2000 (n = 37,401) for incidence of asthma diagnosis up to 3–4 years of age using outpatient and hospitalization records. Asthma cases were age- and sex-matched to five randomly chosen controls from the eligible cohort. We estimated each individual’s exposure to ambient air pollution for the gestational period and first year of life using high-resolution pollution surfaces derived from regulatory monitoring data as well as land use regression models adjusted for temporal variation. We used logistic regression analyses to estimate effects of carbon monoxide, nitric oxide, nitrogen dioxide, particulate matter ≤ 10 μm and ≤ 2.5 μm in aerodynamic diameter (PM₁₀ and PM_2.5), ozone, sulfur dioxide, black carbon, woodsmoke, and proximity to roads and point sources on asthma diagnosis.

Results

A total of 3,482 children (9%) were classified as asthma cases. We observed a statistically significantly increased risk of asthma diagnosis with increased early life exposure to CO, NO, NO₂, PM₁₀, SO₂, and black carbon and proximity to point sources. Traffic-related pollutants were associated with the highest risks: adjusted odds ratio = 1.08 (95% confidence interval, 1.04–1.12) for a 10-μg/m³ increase of NO, 1.12 (1.07–1.17) for a 10-μg/m³ increase in NO₂, and 1.10 (1.06–1.13) for a 100-μg/m³ increase in CO. These data support the hypothesis that early childhood exposure to air pollutants plays a role in development of asthma.     

Effects of Outdoor and Indoor Air Pollution on Respiratory Health of Chinese Children from 50 Kindergartens

Background

Concentrations of ambient air pollution and pollutants in China have changed considerably during the last decade. However, few studies have evaluated the effects of current ambient air pollution on the health of kindergarten children.

Methods

We studied 6730 Chinese children (age, 3–7 years) from 50 kindergartens in 7 cities of Northeast China in 2009. Parents or guardians completed questionnaires that asked about the children’s histories of respiratory symptoms and risk factors. Three-year concentrations of particles with an aerodynamic diameter ≤10 µm (PM₁₀), sulfur dioxide (SO₂), and nitrogen dioxides (NO₂) were calculated at monitoring stations in 25 study districts. A 2-stage regression approach was used in data analyses.

Results

The prevalence of respiratory symptoms was higher among children living near a busy road, those living near chimneys or a factory, those having a coal-burning device, those living with smokers, and those living in a home that had been recently renovated. Among girls, PM₁₀ was associated with persistent cough (odds ratio [OR]_PM10 = 1.44; 95% CI, 1.18–1.77), persistent phlegm (OR_PM10 = 1.36; 95% CI, 1.02–1.81), and wheezing (OR_PM10 = 1.31; 95% CI, 1.04–1.65). NO₂ concentration was associated with increased prevalence of allergic rhinitis (OR = 1.96; 95% CI, 1.27–3.02) among girls. In contrast, associations of respiratory symptoms with concentrations of PM₁₀, SO₂, and NO₂ were not statistically significant among boys.

Conclusions

Air pollution is particularly important in the development of respiratory morbidity among children. Girls may be more susceptible than boys to air pollution.Key words: air pollution, children, respiratory diseases, China     

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.     

Seasonal effect of PM10 concentrations on mortality and morbidity in Seoul, Korea: A temperature-matched case-crossover analysis

Background

Explorations of interactions between air pollution and seasonal changes have represented one approach in examining the consequences of global warming. However, only a few studies have focused on evaluating the effects of seasonal air pollution using data on both morbidity and mortality in Asia.

Method

We examined the associations between PM₁₀ concentrations and mortality and hospital admissions in Seoul, Korea for the periods 2000-2006 and 2001-2006. We employed a temperature-matched case-crossover design, where reference periods matched case days in regard to temperature (same rounded to degrees celsius (°C)), month, and year.

Results

A total of 238,826 deaths were identified, along with 98,570 and 93,553 inpatient admissions for cardiovascular and respiratory diseases, respectively. We found that the association with PM₁₀ and mortality/morbidity increased during the summer. During the study period, 10μg/m³ increase in PM₁₀ was associated with the increase in mortality by 0.28% (95% confidence interval: 0.12, 0.44), 0.51% (0.19, 0.83), and 0.59% (-0.08, 1.26) for non-accidental, cardiovascular, and respiratory causes. 10μg/m³ increase in PM₁₀ was also associated with increase in hospitalization from cardiovascular and respiratory causes by 0.77% (0.53, 1.01) and 1.19% (0.94, 1.44). In the summer, the increase in mortality and hospitalization was 0.57% (0.20, 0.93), 0.64% (-0.10, 1.38), 0.50% (-1.02, 2.05), 1.52% (0.89, 2.16), and 1.55% (0.87, 2.22).

Conclusions

This study provides evidence that the effect of PM₁₀ on mortality and morbidity varies with season and increases during the summer season.     

Public perception and behavior change in relationship to hot weather and air pollution

Background

Changes in climate systems are increasing heat wave frequency and air stagnation, both conditions associated with exacerbating poor air quality and of considerable public health concern.

Objectives

Heat and air pollution advisory systems are in place in many cities for early detection and response to reduce health consequences, or severity of adverse conditions. Whereas the ability to forecast heat waves and/or air pollution episodes has become increasingly sophisticated and accurate, little is known about the effectiveness of advisories in altering public behavior.

Methods

Air quality and meteorological conditions were measured during advisory and control days in Portland, OR and Houston, TX in 2005 and 2006 and 1962 subjects were interviewed by telephone about their perception and response to these conditions.

Results

Elevated ambient temperatures were accurately recognized regardless of air conditioning use; in Portland, respondents resorted to active cooling behavior (AC, fan, etc.), while in Houston no such change was observed. More heat-related symptoms were reported in Portland compared to Houston, probably due to low air conditioning use in the northwest. One-third of study participants were aware of air quality advisories but only ∼10-15% claimed to have changed activities during such an episode. Not the advisory, however, drove their behavior change, but rather the perception of poor air quality, which was not related to PM_2.5 or ozone measurements.

Conclusions

Messages are not reaching the public during potentially hazardous weather and air quality conditions. Climatic forecasts are increasingly predictive but public agencies fail to mount an appropriate outreach response.     

Ambient air pollution the risk of stillbirth: A prospective birth cohort study in Wuhan,China

Background

Recent studies suggest that ambient air pollution exposure during pregnancy is associated with stillbirth occurrence. However, the results on the associations between ambient air pollutants and stillbirths are inconsistent and little is known about the gestational timing of sensitive periods for the effects of ambient air pollutants exposure on stillbirth.

Acute Effects of Outdoor Air Pollution on Emergency Department Visits Due to Five Clinical Subtypes of Coronary Heart Diseases in Shanghai,China

Background

Air pollution can be a contributing cause to the development and exacerbation of coronary heart disease (CHD), but there is little knowledge about the acute effects of air pollution on different clinical subtypes of CHD.

Methods

We conducted a time-series study to investigate the association of air pollution (particulate matter with an aerodynamic diameter < 10 µm [PM₁₀], sulfur dioxide [SO₂], and nitrogen dioxide [NO₂]) on emergency department (ED) visits due to five different subtypes of CHD in Shanghai, China, from 2010 to 2012. We applied an over-dispersed Poisson generalized addictive model to analyze the associations after controlling for the seasonality, day of the week, and weather conditions.

Results

We identified a total of 47 523 ED visits for CHD. A 10-µg/m³ increase in the present-day concentrations of PM₁₀, SO₂, and NO₂ was associated with respective increases of 1.10% (95% confidence interval [CI] 0.33%–1.87%), 0.90% (95% CI −0.14%–1.93%), and 1.44% (95% CI 0.63%–2.26%) for total ED visits for CHD. These associations varied greatly by clinical type, with strong effects on sudden cardiac death, moderate effects on acute myocardial infarction and angina, weak effects on ischemic cardiomyopathy, and no effect on occult CHD. The associations were stronger among people aged 65 years or more than in younger individuals and in the cool season versus the warm one.

Conclusions

Outdoor air pollution may have different effects of air pollution on 5 subtypes of CHD. Our results might be useful for the primary prevention of various subtypes of CHD exacerbated by air pollution.Key words: air pollution, coronary heart disease, clinical subtypes, emergency department visits     

Modifying Effect of Age on the Association between Ambient Ozone and Nighttime Primary Care Visits Due to Asthma Attack

Background

We examined the association between short-term exposure to outdoor air pollution and nighttime primary care visits due to asthma attack. We also investigated the modifying effects of age on this association.

Methods

A case–crossover study was conducted at a primary care clinic in metropolitan Tokyo. The subjects were 308 children aged 0–14 years and 95 adolescents and adults aged 15–64 years. All subjects made visits to the clinic for an asthma attack at between 7 PM and 12 AM. Data on hourly concentrations of particulate matter with a 50% cut-off aerodynamic diameter ≤2.5 µm (PM_2.5), ozone, and nitrogen dioxide (NO₂) were obtained. A conditional logistic regression model was used to estimate odds ratios (ORs) of primary care visits per unit increment of each air pollutant.

Results

Among children, the ORs in warmer months per 10 ppb increment of the 24-hour mean concentration of ozone were 1.16 (95% confidential interval [CI], 1.00–1.33) adjusted for temperature, and 1.29 (95% CI, 1.08–1.55) adjusted for PM_2.5, NO₂, and temperature. With respect to modification of the association by age, the ORs for 24-hour mean concentration of ozone—after adjustment for PM_2.5, NO₂ and temperature in warmer months—in children aged 0–1 years, 2–5 years, and 6–14 years were 1.06 (95% CI, 0.63–1.78), 1.37 (95% CI, 1.05–1.71), and 1.25 (95% CI, 0.87–1.82), respectively. There was no association between ozone and primary care visits among adults.

Conclusions

An association was found between ozone and nighttime primary care visits for asthma attack in warmer months; the association was greater among preschool children.Key words: air pollution, asthma, ozone, particulate matter, preschool children     

Baseline Repeated Measures from Controlled Human Exposure Studies: Associations between Ambient Air Pollution Exposure and the Systemic Inflammatory Biomarkers IL-6 and Fibrinogen

Introduction

Systemic inflammation may be one of the mechanisms mediating the association between ambient air pollution and cardiovascular morbidity and mortality. Interleukin-6 (IL-6) and fibrinogen are biomarkers of systemic inflammation that are independent risk factors for cardiovascular disease.

Objective

We investigated the association between ambient air pollution and systemic inflammation using baseline measurements of IL-6 and fibrinogen from controlled human exposure studies.

Methods

In this retrospective analysis we used repeated-measures data in 45 nonsmoking subjects. Hourly and daily moving averages were calculated for ozone, nitrogen dioxide, sulfur dioxide, and particulate matter ≤ 2.5 μm in aerodynamic diameter (PM_2.5). Linear mixed-model regression determined the effects of the pollutants on systemic IL-6 and fibrinogen. Effect modification by season was considered.

Results

We observed a positive association between IL-6 and O₃ [0.31 SD per O₃ interquartile range (IQR); 95% confidence interval (CI), 0.08–0.54] and between IL-6 and SO₂ (0.25 SD per SO₂ IQR; 95% CI, 0.06–0.43). We observed the strongest effects using 4-day moving averages. Responses to pollutants varied by season and tended to be higher in the summer, particularly for O₃ and PM_2.5. Fibrinogen was not associated with pollution.

Conclusions

This study demonstrates a significant association between ambient pollutant levels and baseline levels of systemic IL-6. These findings have potential implications for controlled human exposure studies. Future research should consider whether ambient pollution exposure before chamber exposure modifies IL-6 response.     

Air pollution exposure and self-reported cardiovascular disease

Background

Studies suggest that increases of fine particle concentrations (PM_2.5) could be linked with a rise in cardiovascular disease. With approximately 25% of American adults aged 30 and older reporting having either heart disease or hypertension it is possible that exposure to air pollution could have significant public health consequences. This study examined the relationship between PM_2.5 and the prevalence of self-reported hypertension and heart disease using data from a large nation-wide survey.

Study design

Adults, 30 years of age or older, who participated in the National Health Interview Survey (NHIS) from 1999 to 2005 were linked to annual PM_2.5 data from the US Environmental Protection Agency (N=132,224). Annual air quality estimates were averaged from monitors within 20 miles of the respondent's residential block group. Respondents who reported being told they had hypertension by a health professional on two or more separate occasions were defined as hypertensive. Heart disease was defined as answering, “yes” to one or more of three NHIS questions on heart disease.

Results

A 10 μg/m³ increase in PM_2.5 exposure was associated with a small elevated risk of hypertension (adjusted odds ratio (OR) 1.05, 95% confidence interval (CI) 1.00-1.10) risk of heart disease (1.08 95% CI 1.00-1.16). The association between PM_2.5 and hypertension was found in non-Hispanic white adults (OR 1.10 95% CI 1.04-1.17) but not in non-Hispanic black or Hispanic adults.

Conclusions

Findings from this study complement those from other studies and indicate that PM_2.5 adversely affects cardiovascular health. Our results are consistent with other studies in showing a small association between exposure to PM_2.5 and cardiovascular outcomes.     

The association between childhood asthma prevalence and monitored air pollutants in metropolitan areas, United States, 2001-2004

Background

Air pollution exposure has been linked to adverse respiratory health outcomes among children, primarily in studies of acute exposures that are often in limited geographic areas. We sought to assess the association between chronic outdoor air pollution exposure, as measured by 12-month averages by county, and asthma among children in metropolitan areas across the nation.

Methods

Eligible children included those aged 3-17 years residing in US metropolitan areas who were sampled in the 2001-2004 National Health Interview Survey (N=34,073). 12-month average air pollutant levels for sulfur dioxide, nitrogen dioxide, ozone and particulate matter were compiled by county for 2000-2004. Eligible children were linked to pollutant levels for the previous 12 months for their county of residence. Adjusted odds ratios of having current asthma or an asthma attack in the past 12 months were estimated in single pollutant logistic regression models.

Results

Children in counties with ozone and, to a less consistent degree, particulate matter levels in the highest quartile were more likely to have current asthma and/or a recent asthma attack than children residing in counties with the lowest pollution levels; the adjusted odds for current asthma for the highest quartile of estimated ozone exposure was 1.56 (95% confidence interval [CI]: 1.15, 2.10) and for recent asthma attack 1.38 (95% CI: 0.99, 1.91). No associations were found with sulfur dioxide or nitrogen dioxide levels.

Conclusion

Although the current US standard for ozone is based on short-term exposure, this cross-sectional study suggests that chronic (12-month) exposure to ozone and particles is related to asthma outcomes among children in metropolitan areas throughout the US.     

Association of daily asthma emergency department visits and hospital admissions with ambient air pollutants among the pediatric Medicaid population in Detroit: Time-series and time-stratified case-crossover analyses with threshold effects

Background

Asthma morbidity has been associated with ambient air pollutants in time-series and case-crossover studies. In such study designs, threshold effects of air pollutants on asthma outcomes have been relatively unexplored, which are of potential interest for exploring concentration–response relationships.

Methods

This study analyzes daily data on the asthma morbidity experienced by the pediatric Medicaid population (ages 2–18 years) of Detroit, Michigan and concentrations of pollutants fine particles (PM_2.5), CO, NO₂ and SO₂ for the 2004–2006 period, using both time-series and case-crossover designs. We use a simple, testable and readily implementable profile likelihood-based approach to estimate threshold parameters in both designs.

Results

Evidence of significant increases in daily acute asthma events was found for SO₂ and PM_2.5, and a significant threshold effect was estimated for PM_2.5 at 13 and 11 μg m⁻³ using generalized additive models and conditional logistic regression models, respectively. Stronger effect sizes above the threshold were typically noted compared to standard linear relationship, e.g., in the time series analysis, an interquartile range increase (9.2 μg m⁻³) in PM_2.5 (5-day-moving average) had a risk ratio of 1.030 (95% CI: 1.001, 1.061) in the generalized additive models, and 1.066 (95% CI: 1.031, 1.102) in the threshold generalized additive models. The corresponding estimates for the case-crossover design were 1.039 (95% CI: 1.013, 1.066) in the conditional logistic regression, and 1.054 (95% CI: 1.023, 1.086) in the threshold conditional logistic regression.

Conclusion

This study indicates that the associations of SO₂ and PM_2.5 concentrations with asthma emergency department visits and hospitalizations, as well as the estimated PM_2.5 threshold were fairly consistent across time-series and case-crossover analyses, and suggests that effect estimates based on linear models (without thresholds) may underestimate the true risk.     

Acute Effects of Air Pollution on Pulmonary Function,Airway Inflammation,and Oxidative Stress in Asthmatic Children

Background

Air pollution is associated with respiratory symptoms, lung function decrements, and hospitalizations. However, there is little information about the influence of air pollution on lung injury.

Objective

In this study we investigated acute effects of air pollution on pulmonary function and airway oxidative stress and inflammation in asthmatic children.

Methods

We studied 182 children with asthma, 9–14 years of age, for 4 weeks. Daily ambient concentrations of sulfur dioxide, nitrogen dioxide, ozone, and particulate matter ≤ 2.5 μm in aerodynamic diameter (PM_2.5) were monitored from two stations. Once a week we measured spirometry and fractional exhaled nitric oxide (Fe_NO), and determined thiobarbituric acid reactive substances (TBARS) and 8-isoprostane—two oxidative stress markers—and interleukin-6 (IL-6) in breath condensate. We tested associations using mixed-effects regression models, adjusting for confounding variables.

Results

Interquartile-range increases in 3-day average SO₂ (5.4 ppb), NO₂ (6.8 ppb), and PM_2.5 (5.4 μg/m³) were associated with decreases in forced expiratory flow between 25% and 75% of forced vital capacity, with changes being −3.1% [95% confidence interval (CI), −5.8 to −0.3], −2.8% (95% CI, −4.8 to −0.8), and −3.0% (95% CI, −4.7 to −1.2), respectively. SO₂, NO₂, and PM_2.5 were associated with increases in TBARS, with changes being 36.2% (95% CI, 15.7 to 57.2), 21.8% (95% CI, 8.2 to 36.0), and 24.8% (95% CI, 10.8 to 39.4), respectively. Risk estimates appear to be larger in children not taking corticosteroids than in children taking corticosteroids. O₃ (5.3 ppb) was not associated with health end points. Fe_NO, 8-isoprostane, and IL-6 were not associated with air pollutants.

Conclusion

Air pollution may increase airway oxidative stress and decrease small airway function of asthmatic children. Inhaled corticosteroids may reduce oxidative stress and improve airway function.     

An association between long-term exposure to ambient air pollution and mortality from lung cancer and respiratory diseases in Japan

Background

Evidence for a link between long-term exposure to air pollution and lung cancer is limited to Western populations. In this prospective cohort study, we examined this association in a Japanese population.

Methods

The study comprised 63 520 participants living in 6 areas in 3 Japanese prefectures who were enrolled between 1983 and 1985. Exposure to particulate matter less than 2.5 µm in aerodynamic diameter (PM_2.5), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂) was assessed using data from monitoring stations located in or nearby each area. The Cox proportional hazards model was used to calculate the hazard ratios associated with the average concentrations of these air pollutants.

Results

The 10-year average concentrations of PM_2.5, SO₂, and NO₂ before recruitment (1974–1983) were 16.8 to 41.9 µg/m³, 2.4 to 19.0 ppb, and 1.2 to 33.7 ppb, respectively (inter-area range). During an average follow-up of 8.7 years, there were 6687 deaths, including 518 deaths from lung cancer. The hazard ratios for lung cancer mortality associated with a 10-unit increase in PM_2.5 (µg/m³), SO₂ (ppb), and NO₂ (ppb) were 1.24 (95% confidence interval: 1.12–1.37), 1.26 (1.07–1.48), and 1.17 (1.10–1.26), respectively, after adjustment for tobacco smoking and other confounding factors. In addition, a significant increase in risk was observed for male smokers and female never smokers. Respiratory diseases, particularly pneumonia, were also significantly associated with all the air pollutants.

Conclusions

Long-term exposure to air pollution is associated with lung cancer and respiratory diseases in Japan.Key words: air pollution, lung neoplasms, nitrogen dioxide, particulate matter, sulfur dioxide