Respiratory Effects Of Air Pollution Research Articles

Long-term exposure to air pollution and lung function among children in China: Association and effect modification.

Children are vulnerable to the respiratory effects of air pollution, and their lung function has been associated with long-term exposure to low air pollution level in developed countries. However, the impact of contemporary air pollution level in developing countries as a result of recent efforts to improve air quality on children's lung function is less understood. We obtained a cross-sectional sample of 617 schoolchildren living in three differently polluted areas in Anhui province, China. 2-year average concentrations of air pollutants at the year of spirometry and the previous year (2017-2018) obtained from district-level air monitoring stations were used to characterize long-term exposure. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and forced expiratory flow between 25 and 75% of FVC (FEF25-75) were determined under strict quality control. Multivariable regression was employed to evaluate the associations between air pollution level and lung function parameters, overall and by demographic characteristics, lifestyle, and vitamin D that was determined by liquid chromatography tandem mass spectrometry. Mean concentration of fine particulate matter was 44.7 μg/m3, which is slightly above the interim target 1 standard of the World Health Organization. After adjusting for confounders, FVC, FEV1, and FEF25-75 showed inverse trends with increasing air pollution levels, with children in high exposure group exhibiting 87.9 [95% confidence interval (CI): 9.5, 166.4] mL decrement in FEV1 and 195.3 (95% CI: 30.5, 360.1) mL/s decrement in FEF25-75 compared with those in low exposure group. Additionally, the above negative associations were more pronounced among those who were younger, girls, not exposed to secondhand smoke, non-overweight, physically inactive, or vitamin D deficient. Our study suggests that long-term exposure to relatively high air pollution was associated with impaired lung function in children. More stringent pollution control measures and intervention strategies accounting for effect modification are needed for vulnerable populations in China and other developing countries.

Assessing the Respiratory Effects of Air Pollution from Biomass Cookstoves on Pregnant Women in Rural India.

Background: In India, biomass fuel is burned in many homes under inefficient conditions, leading to a complex milieu of particulate matter and environmental toxins known as household air pollution (HAP). Pregnant women are particularly vulnerable as they and their fetus may suffer from adverse consequences of HAP. Fractional exhaled nitric oxide (FeNO) is a noninvasive, underutilized tool that can serve as a surrogate for airway inflammation. We evaluated the prevalence of respiratory illness, using pulmonary questionnaires and FeNO measurements, among pregnant women in rural India who utilize biomass fuel as a source of energy within their home. Methods: We prospectively studied 60 pregnant women in their 1st and 2nd trimester residing in villages near Nagpur, Central India. We measured FeNO levels in parts per billion (ppb), St. George’s Respiratory Questionnaire (SGRQ-C) scores, and the Modified Medical Research Council (mMRC) Dyspnea Scale. We evaluated the difference in the outcome distributions between women using biomass fuels and those using liquefied petroleum gas (LPG) using two-tailed t-tests. Results: Sixty-five subjects (32 in Biomass households; 28 in LPG households; 5 unable to complete) were enrolled in the study. Age, education level, and second-hand smoke exposure were comparable between both groups. FeNO levels were higher in the Biomass vs. LPG group (25.4 ppb vs. 8.6 ppb; p-value = 0.001). There was a difference in mean composite SGRQ-C score (27.1 Biomass vs. 10.8 LPG; p-value < 0.001) including three subtotal scores for Symptoms (47.0 Biomass vs. 20.2 LPG; p-value< 0.001), Activity (36.4 Biomass vs. 16.5 LPG; p-value < 0.001) and Impact (15.9 Biomass vs. 5.2 LPG; p-value < 0.001). The mMRC Dyspnea Scale was higher in the Biomass vs. LPG group as well (2.9 vs. 0.5; p < 0.001). Conclusion: Increased FeNO levels and higher dyspnea scores in biomass-fuel-exposed subjects confirm the adverse respiratory effects of this exposure during pregnancy. More so, FeNO may be a useful, noninvasive biomarker of inflammation that can help better understand the physiologic effects of biomass smoke on pregnant women. In the future, larger studies are needed to characterize the utility of FeNO in a population exposed to HAP.

Air pollution in India and related adverse respiratory health effects: past, present, and future directions.

The review describes current status of air pollution in India, summarizes recent research on adverse health effects of ambient and household air pollution, and outlines the ongoing efforts and future actions required to improve air quality and reduce morbidity and mortality because of air pollution in India. Global burden of disease data analysis reveals more than one million premature deaths attributable to ambient air pollution in 2015 in India. More than one million additional deaths can be attributed to household air pollution. Particulate matter with diameter 2.5 μm or less has been causatively linked with most premature deaths. Acute respiratory tract infections, asthma, chronic obstructive pulmonary disease, exacerbations of preexisting obstructive airway disease and lung cancer are proven adverse respiratory effects of air pollution. Targeting air quality standards laid by WHO can significantly reduce morbidity and mortality because of air pollution in India. India is currently exposed to high levels of ambient and household air pollutants. Respiratory adverse effects of air pollution are significant contributors to morbidity and premature mortality in India. Substantial efforts are being made at legislative, administrative, and community levels to improve air quality. However, much more needs to be done to change the 'status quo' and attain the target air quality standards. VIDEO ABSTRACT: http://links.lww.com/COPM/A24.

Short-term exposure to high ambient air pollution increases airway inflammation and respiratory symptoms in chronic obstructive pulmonary disease patients in Beijing, China

BackgroundFew studies have investigated the short-term respiratory effects of ambient air pollution in chronic obstructive pulmonary disease (COPD) patients in the context of high pollution levels in Asian cities. MethodsA panel of 23 stable COPD patients was repeatedly measured for biomarkers of airway inflammation including exhaled nitric oxide (FeNO) and exhaled hydrogen sulfide (FeH2S) (215 measurements) and recorded for daily respiratory symptoms (794person-days) in two study periods in Beijing, China in January–September 2014. Daily ambient air pollution data were obtained from nearby central air-monitoring stations. Mixed-effects models were used to estimate the associations between exposures and health measurements with adjustment for potential confounders including temperature and relative humidity. ResultsIncreasing levels of air pollutants were associated with significant increases in both FeNO and FeH2S. Interquartile range (IQR) increases in PM2.5 (76.5μg/m3, 5-day), PM10 (75.0μg/m3, 5-day) and SO2 (45.7μg/m3, 6-day) were associated with maximum increases in FeNO of 13.6% (95% CI: 4.8%, 23.2%), 9.2% (95% CI: 2.1%, 16.8%) and 34.2% (95% CI: 17.3%, 53.4%), respectively; and the same IQR increases in PM2.5 (6-day), PM10 (6-day) and SO2 (7-day) were associated with maximum increases in FeH2S of 11.4% (95% CI: 4.6%, 18.6%), 7.8% (95% CI: 2.3%, 13.7%) and 18.1% (95% CI: 5.5%, 32.2%), respectively. Increasing levels of air pollutants were also associated with increased odds ratios of sore throat, cough, sputum, wheeze and dyspnea. ConclusionsFeH2S may serve as a novel biomarker to detect adverse respiratory effects of air pollution. Our results provide potential important public health implications that ambient air pollution may pose risk to respiratory health in the context of high pollution levels in densely-populated cities in the developing world.

Air Pollution's Effects on the Human Respiratory System.

The World Health Organization defines air pollution as "any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere." The most common pollutants include particulate matter, carbon monoxide, ozone, nitrogen oxide, and sulfur dioxide. The two types of air pollution, indoor and ambient, both contribute to a host of cardiac and respiratory illnesses. Exposure to excess levels of air pollution is significantly associated with a variety of acute and chronic respiratory illnesses, such as chronic obstructive pulmonary disease, asthma, respiratory allergies, and lung cancer. The effects of air pollution disproportionately impact the extremes of the age distribution, perhaps due to altered immune responses. Athletes and those who exercise outdoors are at greater risk for the respiratory effects of air pollution. This article discusses the epidemiology, types of respiratory diseases, and mechanisms involved in exposure to excess levels of air pollution. Biomedical engineering can contribute to the identification of air pollutants through the design of novel instrumentation using materials based on nanotechnology. Mathematical models can also be developed to characterize the physiological effects of air pollution.

Respiratory effects of air pollution on children.

A substantial proportion of the global burden of disease is directly or indirectly attributable to exposure to air pollution. Exposures occurring during the periods of organogenesis and rapid lung growth during fetal development and early post-natal life are especially damaging. In this State of the Art review, we discuss air toxicants impacting on children's respiratory health, routes of exposure with an emphasis on unique pathways relevant to young children, methods of exposure assessment and their limitations and the adverse health consequences of exposures. Finally, we point out gaps in knowledge and research needs in this area. A greater understanding of the adverse health consequences of exposure to air pollution in early life is required to encourage policy makers to reduce such exposures and improve human health.

The role of non-invasive biomarkers in detecting acute respiratory effects of traffic-related air pollution.

The role of non-invasive methods in the investigation of acute effects of traffic-related air pollution is not clearly established. We evaluated the usefulness of non-invasive biomarkers in detecting acute air pollution effects according to the age of participants, the disease status, their sensitivity compared with lung function tests and their specificity for a type of pollutant. Search terms lead to 535 titles, among them 128 had potentially relevant abstracts. Sixtynine full papers were reviewed, while 59 articles were excluded as they did not meet the selection criteria. Methods used to assess short-term effects of air pollution included analysis of nasal lavage (NAL) for the upper airways, and induced sputum (IS), exhaled breath condensate (EBC) and exhaled nitric oxide (FeNO) for central and lower airways. There is strong evidence that FeNO evaluation is useful independently from subject age, while IS analysis is suitable almost for adults. Biomarker changes are generally observed upon pollutant exposure irrespective of the disease status of the participants. None of the biomarkers identified are specific for a type of pollutant exposure. Based on experimental exposure studies, there is moderate evidence that IS analysis is more sensitive than lung function tests, whereas this is not the case for biomarkers obtained by NAL or EBC. Cells and some cytokines (IL-6, IL-8 and myeloperoxidase) have been measured both in the upper respiratory tract (NAL) and in the lower airways (IS). Overall, the response to traffic exposure seems different in the two compartments. In conclusion, this survey of current literature displays the complexity of this research field, highlights the significance of short-term studies on traffic pollution and gives important tips when planning studies to detect acute respiratory effects of air pollution in a non-invasive way.

Breastfeeding as a Modifier of the Respiratory Effects of Air Pollution in Children

Breastfeeding and air pollution are both important factors for respiratory symptoms and asthma in children. Few studies have examined possible interaction between them on respiratory outcomes. We studied 31,049 Chinese children, ages 2-14 years old, from 25 elementary schools and 50 kindergartens in the Seven Northeastern Cities during 2008-2009. Parents or guardians completed questionnaires about the children's histories of respiratory conditions, risk factors, and feeding methods. Three-year average concentrations of particles with an aerodynamic diameter ≤ 10 µm, sulfur dioxide, nitrogen dioxides, and ozone were calculated from monitoring stations in 25 study districts. We used two-level logistic regressions to examine the effects of exposure, controlling for covariates. Association of air pollution with childhood respiratory conditions was modified by breastfeeding. Compared with children who had been breastfed, those who were not exhibited consistently stronger effects of air pollution. Among non-breastfed children, odds ratios (ORs) per 10 µg/m increase in nitrogen dioxide were 1.40 (95% confidence interval = 1.19-1.64) for cough, 1.41 (1.16-1.71) for phlegm, 1.17 (1.00-1.36) for current wheeze, and 1.25 (1.07-1.46) for doctor-diagnosed asthma. For breastfed children, the ORs were 1.25 (1.09-1.43) for cough, 1.15 (0.99-1.34) for phlegm, 0.97 (0.87-1.08) for current wheeze, and 1.17 (1.05-1.32) for doctor-diagnosed asthma. Breastfeeding was more protective among younger children. Breastfeeding was also associated with reduced effects of passive smoke exposure in children. Breastfeeding is associated with smaller associations between air pollution and respiratory conditions in children, suggesting that breastfeeding reduces susceptibility to the respiratory effects of pollutants.

Diesel exhaust but not ozone increases fraction of exhaled nitric oxide in a randomized controlled experimental exposure study of healthy human subjects

BackgroundFraction of exhaled nitric oxide (FENO) is a promising non-invasive index of airway inflammation that may be used to assess respiratory effects of air pollution. We evaluated FENO as a measure of airway inflammation after controlled exposure to diesel exhaust or ozone.MethodsHealthy volunteers were exposed to either diesel exhaust (particle concentration 300 μg/m3) and filtered air for one hour, or ozone (300 ppb) and filtered air for 75 minutes. FENO was measured in duplicate at expiratory flow rates of 10, 50, 100 and 270 mL/s before, 6 and 24 hours after each exposure.ResultsExposure to diesel exhaust increased FENO at 6 hours compared with air at expiratory flow rates of 10 mL/s (p = 0.01) and at 50 mL/s (p = 0.011), but FENO did not differ significantly at higher flow rates. Increases in FENO following diesel exhaust were attenuated at 24 hours. Ozone did not affect FENO at any flow rate or time point.ConclusionsExposure to diesel exhaust, but not ozone, increased FENO concentrations in healthy subjects. Differences in the induction of airway inflammation may explain divergent responses to diesel exhaust and ozone, with implications for the use of FENO as an index of exposure to air pollution.

Premature infants: the impact of environmental stimuli on lung development in early life

exposure assessment on particulate matter (Han X, 2006), several respiratory outcomes have been associated with air pollution exposure in children. Since lung development continues through adolescence and because of higher minute ventilation and higher levels of physical activity, children are more vulnerable to the adverse effects of air pollution than are adults. The respiratory effects of air pollution can be divided into three major areas: respiratory symptomatology and disease, pulmonary function and airway reactivity. Some contaminants (e.g., benzene, carbon dioxide, carbon monoxide, lead, nitrogen oxide, particulate matter and sulfur dioxide) can cause cancer, birth defects, brain and nerve damage and long term injury to the lungs and airway passages. When certain concentrations and durations are exceeded, these can cause severe injury and even death. Respiratory symptoms associated with air pollution exposure in children include burning eyes and nose, recurrent colds, itchy irritated throat, chronic cough and difficulty breathing. Also noted is increased prevalence of chest wheezing apart from colds or of wheezing most days or nights, of chest tightness, and of cough/phlegm production requiring medical attention. Air pollution is also associated with increased incidence of chest illness and of acute upper and lower respiratory tract infections. Furthermore, increased frequency of symptomatic asthmatic attacks, of exacerbations in persons with chronic cardiopulmonary or other disease, of emergency ward or physician visits, and increased frequency and duration of hospitalization for respiratory conditions have been observed. A meta-analysis showed 1.8 times risk of pneumonia in young children due to exposure to unprocessed solid fuel (Dherani M, 2008). Reductions in pulmonary function such as FEV1 or FVC associated with clinical symptoms have been reported with air pollution. Children may fail to maintain their predicted FEV1 growth curve. Further associations include increase in use of asthma medication and enhanced bronchial reactivity (AAP, 2004; ATS, 2000; Ackermann-Liebrich U, 1992; Braun-Fahrlander C,

Respiratory health effects of diesel particulate matter

Particulate matter (PM) emissions involve a complex mixture of solid and liquid particles suspended in a gas, where it is noted that PM emissions from diesel engines are a major contributor to the ambient air pollution problem. While epidemiological studies have shown a link between increased ambient PM emissions and respiratory morbidity and mortality, studies of this design are not able to identify the PM constituents responsible for driving adverse respiratory health effects. This review explores in detail the physico-chemical properties of diesel PM (DPM) and identifies the constituents of this pollution source that are responsible for the development of respiratory disease. In particular, this review shows that the DPM surface area and adsorbed organic compounds play a significant role in manifesting chemical and cellular processes that if sustained can lead to the development of adverse respiratory health effects. The mechanisms of injury involved included inflammation, innate and acquired immunity, and oxidative stress. Understanding the mechanisms of lung injury from DPM will enhance efforts to protect at-risk individuals from the harmful respiratory effects of air pollutants.

Respiratory Effects of Air Pollutants among Nonsmoking Auto Rickshaw Drivers of Patiala City (Punjab State, India)

Respiratory Effects of Air Pollutants among Nonsmoking Auto Rickshaw Drivers of Patiala City (Punjab State, India)

Interactive Effects of Antioxidant Genes and Air Pollution on Respiratory Function and Airway Disease: A HuGE Review

Susceptibility to the respiratory effects of air pollution varies between individuals. Although some evidence suggests higher susceptibility for subjects carrying variants of antioxidant genes, findings from gene-pollution interaction studies conflict in terms of the presence and direction of interactions. The authors conducted a systematic review on antioxidant gene-pollution interactions which included 15 studies, with 12 supporting the presence of interactions. For the glutathione S-transferase M1 gene (GSTM1) (n=10 studies), only 1 study found interaction with the null genotype alone, although 5 observed interactions when GSTM1 was evaluated jointly with other genes (mainly NAD(P)H dehydrogenase [quinone] 1 (NQO1)). All studies on the glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism (n=11) provided some evidence of interaction, but findings conflicted in terms of risk allele. Results were negative for glutathione S-transferase T1 (GSTT1) (n=3) and positive for heme oxygenase 1 (HMOX-1) (n=2). Meta-analysis could not be performed because there were insufficient data available for any specific gene-pollutant-outcome combination. Overall the evidence supports the presence of gene-pollution interactions, although which pollutant interacts with which gene is unclear. However, issues regarding multiple testing, selective reporting, and publication bias raise the possibility of false-positive findings. Larger studies with greater accuracy of pollution assessment and improved quality of conduct and reporting are required.

Respiratory effects of air pollutants among nonsmoking traffic policemen of Patiala, India

Background:Air pollution due to road traffic is a serious health hazard and thus the persons who are continuously exposed, may be at an increased risk. Although several studies have confirmed the ill effects of air pollutants on the lung function of traffic policemen, only a few have investigated the relationship between respiratory health and duration of exposure in this category of occupationally exposed persons.Aim:The study was carried out with the aim of evaluating the extent of impairment in lung function in traffic policemen in respect to an unexposed control group having the same age group.Materials and Methods:A cross-sectional study was conducted in which the spirometric parameters of a group of 100 nonsmoking traffic policemen, aged 20-55 years, working in and around Patiala city, were compared with those obtained in an age-matched control group, consisting of 100 healthy males, serving in the Punjab Police, who have never done traffic duty and are thus not exposed to traffic pollution. Lung function was done with MEDSPIROR. The data on the overall health status of the subjects was collected using the standard Respirator Medical Evaluation Questionnaire. The statistical analysis was carried out with SPSS PC software version 13.Results:Traffic policemen recorded a significant decline in various parameters, such as forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow rate (PEFR) when compared with controls, and is probably due to exposure to vehicular pollution. It was also observed that in traffic policemen with >8 years of exposure, the values of FVC (2.7 L), FEV1 (1.8 L), and PEFR (7.5 L/s) were significantly lower than those obtained in traffic policemen with <8 years of exposure, in whom the values were 2.9 L, 2.3 L, and 7.7 L/s for FVC, FEV1, and PEFR, respectively.Conclusion:The effect of pollution by vehicular exhausts may be responsible for these pulmonary function impairments.

259 Effects of Traffic Air Pollution on Respiratory Health and Allergies in Schoolchildren

The objective of the study is to investigate gender differences in the respiratory effects of air pollution in schoolchildren. We studied 1397 schoolchildren from two locations in Egypt; Cairo city with high level of air pollution and Shbeen Al Koom in the Delta with low level of air pollution. Lung function testing was done by the Vitalograph spirometer. The Arabic version of ISAAC questionnaire was used (the International Study of Asthma and Allergies in Childhood). Air pollution measurements were collected from the Government sites in both locations. Boys in Shbeen Al Koom had significantly (p< 0.05) higher lung function tests than boys in Cairo. There was no significant differences in lung function tests between girls in both locations. Children in Cairo had significantly (p< 0.01) higher prevalence rates of asthma, rhinitis and eczema than children in Shbeen Al Koom. The prevalence rates of ever rhinitis were 6% and 3% higher in boys and girls in Cairo compared with Shbeen Al Koom, respectively. Children who developed rash less than 2 years of age were 2% and 5% higher in boys and girls in Cairo compared with Shbeen Al Koom, respectively. The prevalence of other allergic symptoms were 2-3% and 3-5% higher in boys and girls in Cairo compared with Shbeen Al Koom, respectively. The present study shows the adverse respiratory effects of exposure to traffic air pollution on schoolchildren showing gender difference. The study will help to implement strategic health intervention programmes to improve the respiratory health of children.

Air pollution and non-respiratory health hazards for children

Air pollution is a global health issue with serious public health implications, particularly for children. Usually respiratory effects of air pollutants are considered, but this review highlights the importance of non-respiratory health hazards. In addition to short-term effects, exposure to criteria air pollutants from early life might be associated with low birth weight, increase in oxidative stress and endothelial dysfunction, which in turn might have long-term effects on chronic non-communicable diseases. In view of the emerging epidemic of chronic disease in low- and middle- income countries, the vicious cycle of rapid urbanization and increasing levels of air pollution, public health and regulatory policies for air quality protection should be integrated into the main priorities of the primary health care system and into the educational curriculum of health professionals.

Urban air pollution, and asthma and COPD hospital emergency room visits

Background:There is little previous information of the effects of size fractioned particulate air pollution and source specific fine particles (PM2.5; <2.5 μm) on asthma and chronic obstructive pulmonary disease (COPD)...

Pulmonary Effects of Stachybotrys chartarum in Animal Studies

Publisher Summary Stachybotrys chartarum is one of the several environmental fungi that can produce very potent toxic compounds. Animal models provide physicians and environmental scientists with useful tools for assessing risks associated with the respiratory effects of air pollutants. The animal studies to date support the view that pulmonary exposure to the spores of S. chartarum leads to hemorrhagic inflammation and impairment of growth. This has been demonstrated by increases in bronchoalveolar lavage (BAL) fluid of inflammatory cells, proinflammatory mediators, hemoglobin, and proteins along with changes in pulmonary surfactant. Although the earlier experiments were conducted with relatively high doses, recent findings indicate that lower doses, which appear to be closer to the concentrations encountered in indoor air, can elicit similar symptoms. The results of animal studies based on different experimental designs are difficult to compare because of many variables—including spore toxicity, viability, and content of fungal proteins in addition to species, strains, age of animals, and route of administration.

Respiratory effects of air pollutants among asthmatics in central Taiwan.

The authors investigated the relationship between respiratory effects and air pollutants among asthmatics in central Taiwan. A total of 12,926 subjects were selected from 8 junior high schools. Data about monthly hospital admissions for respiratory illnesses were collected over a period of 1 yr from the National Insurance Bureau. Data included how frequently subjects purchased medication and the respiratory symptoms recorded by clinic and hospital personnel. Pulmonary function tests were administered to 20% of the total study population, which was selected randomly. Data about monthly levels of air pollutants (i.e., particulate matter 10 pm and less [PM10], ozone [O3], sulfur dioxide [SO2], and nitrogen dioxide [NO2]) were provided by Taiwan's Environmental Protection Agency. The prevalence rates of asthma were correlated significantly with NO2 (r = .63) and 03 (r = .51) concentrations. Levels of NO2 and PM10 were correlated significantly with monthly hospital admissions. Forced vital capacity, forced expiratory volume in 1 sec, and peak expiratory flow for asthmatics in central Taiwan were 6-11% lower than normal predicted values for the general Taiwanese student population, adjusted for age, height, and weight. In conclusion, the increased risk of asthma and the frequency of monthly hospital admissions among asthmatics may be correlated positively with pollution levels-especially NO2 and PM10. air pollutants, asthma, mon

Modulation of the acute respiratory effects of winter air pollution by serum and dietary antioxidants: a panel study.

This study investigated whether a high dietary intake or serum concentration of antioxidant (pro-) vitamins could attenuate the acute respiratory effects of air pollution in panels of adults (n = 227) aged 50-70 yrs with chronic respiratory symptoms in two winters starting in 1993/1994. Subjects performed daily peak expiratory flow (PEF) measurements in the morning and evening and reported the occurrence of respiratory symptoms in two regions (urban and nonurban) each winter. Logistic regression analysis was used with the prevalences of large PEF decrements as dependent variables and air pollution levels as independent variables. Analyses were performed separately for subjects below and above the median levels of serum beta-carotene and the intake of dietary vitamin C and beta-carotene. Subjects with low levels of serum beta-carotene more often had large PEF decrements when particles <10 microm in diameter or black smoke levels which were higher compared to subjects with high levels of serum beta-carotene. The same results tended to be observed for dietary vitamin C or beta-carotene, but there were less significant air pollution effects in the low dietary antioxidant group. The results suggest that serum beta-carotene and to a lesser extent dietary vitamin C and beta-carotene may attenuate peak expiratory flow decrements due to air pollution in subjects with chronic respiratory symptoms.