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Biomedical subjects

D W Dockery

Publications and source records attributed to D W Dockery.

At least 55 records · Page 3Linked to original sources
PubMed1996

Health effects of acid aerosols on North American children: pulmonary function.

We examined the health effects of exposure to acidic air pollution among children living in 24 communities in the United States and Canada. Parents of children between the ages of 8 and 12 completed a self-administered questionnaire and provided consent for their child to perform a standardized forced expiratory maneuver at school in 22 of these communities. Air quality and meteorology were measured in each community for the year preceding the pulmonary function tests. Forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) measurements of 10,251 white children were examined in a two-stage regression analysis that adjusted for age, sex, height, weight, and sex-height interaction. In this study, a 52 nmol/m3 difference in annual mean particle strong acidity was associated with a 3.5% (95% CI, 2.0-4.9) decrement in adjusted FVC and a 3.1% (95% CI, 1.6-4.6) decrement in adjusted FEV1.0. The FVC decrement was larger, although not significantly different, for children who were lifelong residents of their communities (4.1%, 95% CI, 2.5-5.8). The relative odds for low lung function (that is, measured FVC less than or equal to 85% of predicted), was 2.5 (95% CI, 1.8-3.6) across the range of particle strong acidity exposures. These data suggest that long-term exposure to ambient particle strong acidity may have a deleterious effect on lung growth, development, and function.

Aerosols↗
PubMed1996

Race, asthma, and persistent wheeze in Philadelphia schoolchildren.

OBJECTIVES: Many studies show asthma to be more common in Black than in White children. This study assessed how much of this difference remains after adjustment for other potentially race-associated predictors of asthma. METHODS: We assessed the predictors of active diagnosed asthma and persistent wheeze in 1416 Black and White Philadelphia children aged 9 to 11 years, as reported by parents. RESULTS: Black race remained a significant predictor of active diagnosed asthma (odds ratio [OR] = 2.3; 95% confidence interval [CI] = 1.3, 4.1) but not of persistent wheeze (OR = 1.0; 95% CI = 0.6, 1.8). The excess risk of asthma in Black children was not appreciably altered by adjustment for other demographic and environmental factors. CONCLUSIONS: Black race is an important risk factor for active diagnosed asthma in these urban children, a relationship not explained by social factors. This finding and the lack of an association of race with persistent wheeze after adjustment for social factors suggest that race may be more important to the acquisition of an asthma diagnosis than to the prevalence of the symptoms.

Asthma↗
PubMed1996

[Association of air pollution with unscheduled outpatient visits in Beijing Longfu Hospital, 1991].

Outpatient visits to Beijing Longfu Hospital, a community-based hospital, were analyzed to assess the association of air pollution with daily outpatient visits in 1991. Measurements of total suspended particulate (TSP) were available for 224 days (mean was 359 micrograms/m3) and sulfur dioxide (SO2) for 221 days (mean was 124 micrograms/m3). The effects of TSP and SO2 were assessed by linear regressions adjusting for temperature, humidity, seasons and the workdays as covariables with a Markov correction for auto-correlation in time series data. There was a significant exposure-response relationship between TSP level and non-surgery outpatient visits but not for surgery visits. SO2 was only significantly associated with pediatric visits.

Air Pollutants↗
PubMed1996

Is daily mortality associated specifically with fine particles?

Recent epidemiologic studies have consistently reported increased daily mortality associated with exposures to particulate air pollution. Currently, particulate mass is measured as particles smaller than 10 microns (PM10). Fine (PM2.5) and coarse (PM10-PM2.5) mass and sulfate particle concentrations were measured in six eastern U.S. cities for eight years, and aerosol acidity concentrations were measured for approximately one year. Daily mortality for these metropolitan areas was combined with particulate air pollution and weather measurements. City-specific associations with each measure of particle pollution were estimated by Poisson regression, adjusting for time trends and weather by nonparametric methods. Combined effect estimates were calculated as the inverse variance weighted mean of the city-specific estimates. PM10, PM2.5, and SO4= were each significantly associated with increased daily mortality, while no associations were found with coarse mass nor with aerosol acidity (H+) concentrations. The strongest association was found with PM2.5. A 10 micrograms/m3 increase in two-day mean PM2.5 was associated with a 1.5% (95% CI 1.1% to 1.9%) increase in total daily mortality. Somewhat larger increases were found for deaths caused by chronic obstructive pulmonary disease (+3.3%) and by ischemic heart disease (+2.1%). These data suggest that increased daily mortality is specifically associated with particle mass constituents found in the aerodynamic diameter size range under 2.5 microns, that is, with combustion-related particles.

Air Pollution↗
PubMed1995

Age, period, and cohort effects on pulmonary function in a 24-year longitudinal study.

This paper proposes the use of two-factor models (age-period and age-cohort models) to estimate age, period, and cohort effects on pulmonary function by using the data collected in a 24-year longitudinal study in the Netherlands from 1965 to 1990. The analysis included 18,363 pulmonary function measurements on 6,148 subjects aged 20-54 years at the initial visit. The subjects were grouped into four birth cohorts (before 1923, 1923-1934, 1935-1946, and after 1946) and four survey periods (1965-1972, 1973-1978, 1979-1984, and 1985-1990). In the age-cohort model, the decrement in forced expiratory volume in 1 second (FEV1) associated with a yearly increase in age was 28.3 +/- 3.7 ml/year for a man 176 cm tall and 16.0 +/- 1.9 ml/year for a woman 163 cm tall. The estimated acceleration of decline with aging was significant for both men (beta = -0.212; standard error = 0.079 ml) and women (beta = -0.346; standard error = 0.058 ml). Compared with that of the cohort born before 1923, the average level of FEV1 was estimated to increase by 156, 277, and 379 ml, respectively, for the three younger cohorts in men (p = 0.01) and by 133, 213, and 328 ml for the three younger cohorts in women (p < 0.01). In the age-period model, the estimated linear age effect on FEV1 was 36.2 +/- 4.2 ml/year for a man and 30.5 +/- 2.3 ml/year for a woman. The age quadratic term was significant for women, but not for men. Average FEV1 was estimated to be increased by 141, 169, and 250 ml, respectively, for the periods 1973-1978, 1979-1984, and 1985-1990 in men and by 131, 138, and 219 ml in women. These period effects were significant for both men and women. In summary, this study applied the two-factor models to estimate cross-sectional and longitudinal effects of aging on FEV1 and demonstrated significant period and cohort effects, which could be attributed in part to changes in air pollutants, respiratory infections, vaccinations, types of cigarettes, diet, and lifestyles over time.

Age Factors↗
PubMed1995

The association of ambient air pollution with twice daily peak expiratory flow rate measurements in children.

A stratified sample of 83 children living in Uniontown, Pennsylvania, reported twice daily peak expiratory flow rate (PEFR) measurements on 3,582 child-days during the summer of 1990. Upon arising and before retiring, each child recorded the time, three PEFR measurements, and the presence of cold, cough, or wheeze symptoms. Ambient air pollution, including particle-strong acidity, was measured separately during the day (8 a.m. to 8 p.m.) and at night. Each child's maximum PEFR for each session was expressed as the deviation from his or her mean PEFR over the study and adjusted to a standard of 300 liters/minute. The session-specific average deviation was then calculated across all of the children. A second-order autoregressive model for PEFR was developed, which included a separate intercept for evening measurements, trend, temperature, and 12-hour average air pollutant concentration weighted by the number of hours each child spent outdoors during the previous 12-hour period. The results are expressed in terms of the interquartile range for each pollutant. A 12-hour exposure to a 125-nmol/m3 increment in particle-strong acidity was associated with a -2.5 liters/minute deviation in the group mean PEFR (95% confidence interval (CI) -4.2 to -0.8) and with increased cough incidence (odds ratio (OR) = 1.6, 95% CI 1.1 to 2.4). A 30-ppb increment in ozone for 12 hours was associated with a similar deviation in PEFR levels (-2.8, 95% CI -67 to 1.1). The association between PEFR and particle-strong acidity was observed among the 60 children who were reported as symptomatic on the prior symptom questionnaire (-2.5, 95% CI -4.5 to -0.5). The authors conclude that summer occurrences of excessive acid aerosol and particulate pollution are associated with declines in peak expiratory flow rates in children.

Aerosols↗
PubMed1995

Racial differences in the association between maternal smoking during pregnancy and lung function in children.

We recently reported that suburban white schoolchildren whose mothers smoked during pregnancy have significantly reduced lung function. Because inner-city and minority children may be at greater risk for respiratory morbidity, we evaluated the relationship between maternal smoking during pregnancy and lung function in 493 white and 383 black schoolchildren 9 to 11 yr of age in three areas of Philadelphia. The child's passive smoking history was determined from reports by the mother. Spirometry was performed at school. After adjusting for height, weight, age, sex, area of city, race, socioeconomic status, and current exposure to environmental tobacco smoke at home, maternal smoking during pregnancy was associated with significant deficits in FEF25-75 (-8.1%) and FEV1/FVC (-2.0%). The observed deficits were larger for black children than for white children, and they were larger for boys than for girls. These results provide additional evidence of an association between maternal smoking during pregnancy and reduced pulmonary function in children, and they suggest that the association may be modified by race and/or sex.

Black People↗
PubMed1995

Particulate air pollution as a predictor of mortality in a prospective study of U.S. adults.

Time-series, cross-sectional, and prospective cohort studies have observed associations between mortality and particulate air pollution but have been limited by ecologic design or small number of subjects or study areas. The present study evaluates effects of particulate air pollution on mortality using data from a large cohort drawn from many study areas. We linked ambient air pollution data from 151 U.S. metropolitan areas in 1980 with individual risk factor on 552,138 adults who resided in these areas when enrolled in a prospective study in 1982. Deaths were ascertained through December, 1989. Exposure to sulfate and fine particulate air pollution, which is primarily from fossil fuel combustion, was estimated from national data bases. The relationships of air pollution to all-cause, lung cancer, and cardiopulmonary mortality was examined using multivariate analysis which controlled for smoking, education, and other risk factors. Although small compared with cigarette smoking, an association between mortality and particulate air pollution was observed. Adjusted relative risk ratios (and 95% confidence intervals) of all-cause mortality for the most polluted areas compared with the least polluted equaled 1.15 (1.09 to 1.22) and 1.17 (1.09 to 1.26) when using sulfate and fine particulate measures respectively. Particulate air pollution was associated with cardiopulmonary and lung cancer mortality but not with mortality due to other causes. Increased mortality is associated with sulfate and fine particulate air pollution at levels commonly found in U.S. cities. The increase in risk is not attributable to tobacco smoking, although other unmeasured correlates of pollution cannot be excluded with certainty.

Air Pollutants↗
PubMed1995

Epidemiologic studies on short-term effects of low levels of major ambient air pollution components.

Since the development of the World Health Organization (WHO) Air Quality Guidelines for Europe, a large number of epidemiologic studies have been published documenting effects of major air pollutants on health at concentrations below existing guidelines and standards. In this review, recent studies are discussed that permit some evaluation of short-term health effects observed at exposure levels lower than the current WHO Guidelines or U.S. Environmental Protection Agency (U.S. EPA) standards. Some studies have been conducted at concentration levels that never exceeded existing guidelines or standards. Other studies have been conducted at exposure levels sometimes exceeding current guidelines or standards. The published analyses of several of these studies permit evaluation of low-level health effects either because analyses were restricted to levels not exceeding the guidelines or graphic analyses were reported suggesting effects at these low levels. For ambient ozone, effects on lung function of subjects exercising outdoors have now been documented at 1-hr maximum levels not exceeding 120 micrograms/m3, i.e., half the current U.S. EPA standard. One study even suggests that such effects occur at levels below 100 micrograms/m3. Several studies are now available documenting effects of particulate air pollution on health in the virtual absence of SO2. Effects on mortality and hospital admissions for asthma have been documented at levels not exceeding 100 micrograms/m3, expressed as 24-hr average inhalable particles PM10 concentration. Effects on lung function, acute respiratory symptoms, and medication use have been found at 24-hr average PM10 levels not exceeding 115 micrograms/m3. When the WHO Air Quality Guidelines and the U.S. EPA standard for PM10 were developed, there were no studies available on health effects of PM10. In this review, we include nine studies documenting health effects of measured PM10 at low levels of exposure, indicating that there is now an entirely new epidemiologic database that can be evaluated in the process of revising current guidelines and standards. The low levels of exposure at which effects on health were seen underscore the urgent need for such reevaluations.

Air Pollutants↗
PubMed1995

Comparing FEV1 in adults in two community-based studies.

Data collected in two large-scale longitudinal respiratory studies were analyzed to estimate age-related changes in FEV1 and to determine the between-study differences in change in FEV1 among nonsmoking participants. Two adult cohorts in the Netherlands were followed up for 21 years at 3-year intervals and a cohort of adults in 6 cities in the eastern United States was followed up for 6 years. The age distributions and follow-up rate differed for the two studies. The mean rates of decline in FEV1 for 50-year old male and female never smokers were 27.9 +/- 2.8 mL/yr and 22.1 +/- 0.9 mL/yr, respectively, in the Netherlands cohort. The estimates for men and women in the Six Cities cohort were 33% and 32% greater, respectively, than those for the Netherlands cohort (p < 0.01). The estimated rate of decline in FEV1 associated with each 1-year increase in age was 0.50 +/- 0.12 mL/yr for men and 0.61 +/- 0.08 mL/yr for women in the Netherlands cohort. This estimate was comparable for the Six Cities women and the Netherlands women but significantly different for the two cohorts of men. Inclusion of survey (period) effect in the regression model had only a trivial influence on accelerated rate of decline in FEV1 and did not alter the more rapid acceleration of decline in FEV1 among the Six Cities men. The present study also showed that use of a "prediction equation" for age adjustment to compare across population samples may produce a biased conclusion if the estimated rate of decline in FEV1 associated with age is different and the age distributions are different for the two populations. In addition, height adjustment for FEV1 was found to have a negligible influence on the longitudinal estimates of FEV1 decline in both study samples. In conclusion, substantial between study variation in decline in FEV1 occurs despite use of similar data analysis techniques. Differences in the initial age distributions and loss to follow-up appeared to be important factors in this analysis.

Adult↗
PubMed1994

Maternal smoking during pregnancy as a predictor of lung function in children.

Recent studies have suggested that prenatal exposure to environmental tobacco smoke may lead to lower lung function in infants. The authors examined the relation of maternal smoking during pregnancy to persistent deficits in the lung function of older children. Subjects were 8,863 nonsmoking white children aged 8-12 years from 22 North American communities. Information on maternal smoking was provided by the child's mother. Pulmonary function testing of the children was conducted at school in 1988-1991. Children whose mothers smoked during pregnancy, whether or not they still smoked in the year prior to the study, had significantly lower lung function than did children whose mothers did not smoke in either period. On average, forced expiratory flow between 65 and 75 percent of forced vital capacity (FEF65-75%), forced expiratory flow between 25 and 75 percent of forced vital capacity (FEF25-75%), and forced expiratory volume in 3/4 of a second (FEV0.75) were 5.7%, 4.9%, and 1.7% lower, respectively, for children whose mothers smoked during pregnancy. After adjusting for maternal smoking during pregnancy, the authors found that current maternal smoking was not associated with significant differences on any lung function measure. These results show a persistent deficient in lung function associated with maternal smoking during pregnancy that is not explained by current maternal smoking alone. The strongest effects were observed with pulmonary function measures of flow in the small airways. The authors conclude that the effects of exposure to tobacco smoking by the mother during pregnancy and/or environmental tobacco smoke exposure in the first few years of life persist into childhood and may affect the pulmonary function attained throughout the child's life.

Child↗
PubMed1994

Concentration of indoor particulate matter as a determinant of respiratory health in children.

The effect of passive exposure to environmental tobacco smoke in the home on respiratory symptoms and pulmonary function level was studied in a cohort of white children aged 7-11 years examined in six US cities in 1983-1988. For 2,994 children with questionnaire-based exposure data, passive exposure to an additional pack of cigarettes smoked daily in the home was associated with increased incidence of lower respiratory symptoms (odds ratio (OR) = 1.25, 95% confidence interval (CI) 1.10-1.42). For 1,237 children with two consecutive 1-week measurements in both winter and summer, a 30-micrograms/m3 increase in the annual average indoor concentration of respirable particulate matter with an aerodynamic diameter of < 2.5 microns (PM2.5)--that is, approximately the effect of one pack per day of smoking--was marginally associated with an increased cumulative incidence of lower respiratory symptoms (OR = 1.13, 95% CI 0.99-1.30). Indoor measurements of PM2.5 showed no direct association with children's pulmonary function measurements. Children whose mothers smoked during pregnancy showed a reduction of -2.6% (95% CI -5.2% to 0.1%) in volume-adjusted forced expiratory flow rates. Therefore, current indoor exposure to PM2.5 increases the cumulative incidence of lower respiratory symptoms, but is only weakly associated with decreased pulmonary function level in preadolescent children.

Air Pollution, Indoor↗
PubMed1994

Genotoxicity to human cells induced by air particulates isolated during the Kuwait oil fires.

In an effort to examine the potential of exposure to soot from the 1991 oil fires in the Kuwait desert for inducing genetic effects we studied the in vitro genotoxicity of this material. Air particulates isolated near the Kuwait oil fires were studied using three assays. Dose-dependent increases were observed for both sister chromatid exchanges in human peripheral blood lymphocytes and mutation at the hprt locus in the metabolically competent human lymphoblast cell line AHH-1. Similar magnitudes of response were seen using these two assays when testing a standard air particulate sample which had been isolated from the Washington, DC, area. Using the 32P-postlabeling assay, no increase in DNA adduct formation was observed in AHH-1 cells treated with particulates isolated from sampling in Kuwait.

Air Pollutants↗
PubMed1994

Gender- and race-specific effects of asthma and wheeze on level and growth of lung function in children in six U.S. cities.

The gender-and race-specific effects of asthma/wheeze on pulmonary function level and annual growth velocity were studied in a cohort of 10,792 white and 944 black children 6 to 18 yr of age, examined annually between 1974 and 1989 in six U.S. cities. In comparison with white boys who never reported asthma or wheeze, FEV1 levels were 5.7% lower and FEF 25-75 levels were 16.9% lower for white boys with a diagnosis of asthma who reported wheeze symptoms in the past year. White girls with asthma and wheeze had FEV1 levels that were 3.4% lower and FEF25-75 levels that were 13.6% lower than white girls with never-asthma/wheeze. Asthma with wheeze was associated with a greater percent deficit in FEV1 level in boys than in girls (p < 0.01) and, particularly in preadolescence, with a significant percent increment in FVC level (1.6%) for girls but not for boys. The diagnosis of asthma with or without wheeze in the past year was associated with a greater deficit in level of lung function than the reporting of wheeze symptoms in a child without the diagnosis of asthma. The prevalence of asthma and wheeze was higher among blacks, but no race differences were found in the effects of asthma or wheeze on level of FEV1 and FEF25-75. Compared with white adolescent female ever asthmatics with no medication use, FEV1 level was 5.8% lower for those with routine medication use and 7.8% lower for those with routine and additional medication use. Although white girls with wheeze but no diagnosis of asthma had slightly slower growth of FEV1 (0.3% per year) than did white girls without asthma or wheeze, children with asthma did not have slower annual growth in percent terms. In absolute terms, growth of FEV1 was 14.7 ml/yr and FEF25-75 was 47 ml/s/yr slower for asthmatic white boys with wheeze than for those without asthma; for girls with asthma and wheeze growth of FEF25-75 was 29 ml/s/yr slower. We conclude that in absolute terms, but not in percent terms, the pulmonary function deficits associated with asthma and wheeze increase throughout childhood. In the preadolescent and adolescent years, the mechanical properties of the lungs and the inflammatory process in asthmatics may differ by gender, leading to gender differences in their pulmonary function. We also conclude that lung function may not return to normal, even when asthmatics become asymptomatic.

Adolescent↗
PubMed1994

A longitudinal study of the effects of parental smoking on pulmonary function in children 6-18 years.

The association between parental cigarette smoking and children's pulmonary function was investigated in 8,706 nonsmoking white children, followed annually by questionnaire and spirometry between 6 and 18 yr. Exposure to maternal and paternal smoking was each divided into three components: exposure in the first 5 yr of life, cumulative exposure between age 6 and the year prior to each visit; parental smoking status reported at each visit. Regression splines were used to assess the effects of parental smoking on the level and growth rate of pulmonary function adjusting for age, height, city of residence, and parental education. Models best predicting pulmonary function level included current maternal smoking and exposure to maternal smoking in the first 5 yr of life but did not include the other measures of parental smoking. After adjusting for early exposure, current maternal smoking for each pack/d was associated with a reduced level of FEV1 (-0.4%, 95% CI: -0.9, 0.1), FEV1/FVC (-0.6%, 95% CI: -0.9, -0.4), and FEF25-75% (-2.3%, 95% CI: -3.6, -1.0) in children 6 to 10 yr. These effects were slightly smaller in children 11 to 18 yr. Adjusting for current maternal smoking, those exposed to maternal smoking in the first 5 yr of life had higher FVC (+0.5%, 95% CI: -0.1, 1.2) and lower FEV1/FVC (-0.7%, 95% CI: -1.1, -0.4) and FEF25-75% (-2.8%, 95% CI: -4.4, -1.2) than those not exposed in children 6 to 10 yr.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Acute effects of summer air pollution on respiratory symptom reporting in children.

A daily diary of respiratory symptoms was collected from the parents of 1,844 school children in six U.S. cities to study the association between ambient air pollution exposures and respiratory illness. A cohort of approximately 300 elementary school children in each of six communities were asked to keep a daily log of the study child's respiratory symptoms for one year. Daily measurements of ambient sulfur dioxide, nitrogen dioxide, ozone, inhalable particles (PM10), respirable particles (PM2.5), light scattering, and sulfate particles were made, along with integrated 24-h measures of aerosol strong acidity. The analyses were limited to the five warm season months between April and August. Significant associations were found between incidence of coughing symptoms and incidence of lower respiratory symptoms and PM10, and a marginally significant association between upper respiratory symptoms and PM10. There was no evidence that other measures of particulate pollution including aerosol acidity were preferable to PM10 in predicting incidence of respiratory symptoms. Significant associations in single pollutant models were also found between sulfur dioxide or ozone and incidence of cough, and between sulfur dioxide and incidence of lower respiratory symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗