Relationships of mortality with the fine and coarse fractions of long-term ambient PM10 concentrations in nonsmokers.

In a cohort of 6338 California Seventh-day Adventists, we previously observed for males associations between long-term concentrations of particulate matter (PM) with an aerodynamic diameter less than 10 microm (PM10) and 15-year mortality due to all natural causes (ANC) and lung cancer (LC) listed as underlying causes of death and due to nonmalignant respiratory disease listed as either the underlying or a contributing (CRC) cause of death. The purpose of this analysis was to determine whether these outcomes were more strongly associated with the fine (PM2.5) or the coarse (PM2.5-10) fractions of PM10. For participants who lived near an airport (n=3769), daily PM2.5 concentrations were estimated from airport visibility, and on a monthly basis, PM2.5-10 concentrations were calculated as the differences between PM10 and PM2.5. Associations between ANC, CRC, and LC mortality (1977-1992) and mean PM10, PM2.5, and PM2.5-10 concentrations at study baseline (1973-1977) were assessed using Cox proportional hazards models. Magnitudes of the PM10 associations for the males of this subgroup were similar to those for the males in the entire cohort although not statistically significant due to the smaller numbers. In single-pollutant models, for an interquartile range (IQR) increase in PM10 (29.5 microg/m3), the rate ratios (RRs) and 95% confidence intervals (CI) were 1.15 (0.94, 1.41) for ANC, 1.48 (0.93, 2.34) for CRC, and 1.84 (0.59, 5.67) for LC. For an IQR increase in PM2.5 (24.3 microg/m3), corresponding RRs (95% CI) were 1.22 (0.95, 1.58), 1.64 (0.93, 2.90), and 2.23 (0.56, 8.94), and for an IQR increase in PM2.5-10 (9.7 microg/m3), corresponding RRs (95% CI) were 1.05 (0.92, 1.20), 1.19 (0.88, 1.62), and 1.25 (0.63, 2.49), respectively. When both PM25 and PM2.5-10 were entered into the same model, the PM2.5 estimates remained stable while those of PM2.5-10 decreased. We concluded that previously observed associations of long-term ambient PM10 concentration with mortality for males were best explained by a relationship of mortality with the fine fraction of PM10 rather than with the coarse fraction of PM10.

Long-term ambient ozone concentration and the incidence of asthma in nonsmoking adults: the AHSMOG Study.

We conducted a prospective study of a cohort of 3091 nonsmokers, ages 27 to 87 years, to evaluate the association between long-term ambient ozone exposure and development of adult-onset asthma. Over a 15-year period, 3.2% of males and 4.3% of females reported new doctor diagnoses of asthma. For males, we observed a significant relationship between report of doctor diagnosis of asthma and 20-year mean 8-h average ambient ozone concentration (relative risk (RR)=2.09 for a 27 ppb increase in ozone concentration, 95% CI=1.03 to 4.16). We observed no such relationship for females. Other variables significantly related to development of asthma were a history of ever-smoking for males (RR=2.37, 95% CI=1.13 to 4.81), and for females, number of years worked with a smoker (RR=1.21 for a 7-year increment, 95% CI=1.04 to 1.39), age (RR=0.61 for a 16-year increment, 95% CI=0.44 to 0.84), and a history of childhood pneumonia or bronchitis (RR=2.96, 95% CI=1.68 to 5.03). Addition of other pollutants (PM10, SO4, NO2, and SO2) to the models did not diminish the relationship between ozone and asthma for males. These data suggest that long-term exposure to ambient ozone is associated with development of asthma in adult males.

Long-term inhalable particles and other air pollutants related to mortality in nonsmokers.

Long-term ambient concentrations of inhalable particles less than 10 microm in diameter (PM10) (1973- 1992) and other air pollutants-total suspended sulfates, sulfur dioxide, ozone (O3), and nitrogen dioxide-were related to 1977-1992 mortality in a cohort of 6,338 nonsmoking California Seventh-day Adventists. In both sexes, PM10 showed a strong association with mortality for any mention of nonmalignant respiratory disease on the death certificate, adjusting for a wide range of potentially confounding factors, including occupational and indoor sources of air pollutants. The adjusted relative risk (RR) for this cause of death as associated with an interquartile range (IQR) difference of 43 d/yr when PM10 exceeded 100 microg/m3 was 1.18 (95% confidence interval [CI]: 1.02, 1.36). In males, PM10 showed a strong association with lung cancer deaths-RR for an IQR was 2.38 (95% CI: 1.42, 3.97). Ozone showed an even stronger association with lung cancer mortality for males with an RR of 4.19 (95% CI: 1.81, 9.69) for the IQR difference of 551 h/yr when O3 exceeded 100 parts per billion. Sulfur dioxide showed strong associations with lung cancer mortality for both sexes. Other pollutants showed weak or no association with mortality.

Respiratory symptoms and pulmonary function in an elderly nonsmoking population.

OBJECTIVE: To examine risk factors for chronic airway disease (CAD) in elderly nonsmokers, as determined by pulmonary function tests (PFTs), and to correlate reported respiratory symptoms with PFT measures. DESIGN: An observational survey. SETTING: Several communities in California. MEASUREMENTS: Exposures and respiratory history were assessed by standardized questionnaire. PFTs were performed and prediction equations derived. RESULTS: Significant risk factors for obstruction on PFTs in multiple logistic regression included reported environmental tobacco smoke (ETS) exposure (relative risk [RR]=1.44), parental CAD or hay fever (RR=1.47), history of childhood respiratory illness (RR=2.15), increasing age, and male sex. The number of years of past smoking was of borderline significance (RR=1.29 for 10 years of smoking; p=0.06). The prevalence of obstruction on PFTs was 24.9% in those with definite symptomatic CAD, compared with 7.5% in those with no symptoms of CAD. The prevalence of obstruction was 36.0% among those with asthma and 70.6% among those with emphysema. Also, symptomatic CAD correlated with reduction in lung function by analysis of covariance. The mean percent predicted FEV1 adjusted for covariates was 90.6% in persons with definite symptoms of CAD, compared with 97.8% in those without it (p < 0.001). CONCLUSIONS: Age, sex, parental history, childhood respiratory illness, and reported ETS exposures were significant risk factors for obstruction on PFTs. Self-reported respiratory symptoms also correlated significantly with PFTs.

Long-term concentrations of ambient air pollutants and incident lung cancer in California adults: results from the AHSMOG study.Adventist Health Study on Smog.

The purpose of this study was to evaluate the relationship of long-term concentrations of ambient air pollutants and risk of incident lung cancer in nonsmoking California adults. A cohort study of 6,338 nonsmoking, non-Hispanic, white Californian adults, ages 27-95, was followed from 1977 to 1992 for newly diagnosed cancers. Monthly ambient air pollution data were interpolated to zip code centroids according to home and work location histories, cumulated, and then averaged over time. The increased relative risk (RR) of incident lung cancer in males associated with an interquartile range (IQR) increase in 100 ppb ozone (O3) was 3.56 [95% confidence interval (CI), 1.35-9.42]. Incident lung cancer in males was also positively associated with IQR increases for mean concentrations of particulate matter <10 microm (PM10; RR = 5.21; CI, 1.94-13.99) and SO2 (RR = 2.66; CI, 1.62-4.39). For females, incident lung cancer was positively associated with IQR increases for SO2 (RR = 2.14; CI, 1.36-3.37) and IQR increases for PM10 exceedance frequencies of 50 microg/m3 (RR = 1.21; CI, 0.55-2.66) and 60 microg/m3 (RR = 1.25; CI, 0.57-2.71). Increased risks of incident lung cancer were associated with elevated long-term ambient concentrations of PM10 and SO2 in both genders and with O3 in males. The gender differences for the O3 and PM10 results appeared to be partially due to gender differences in exposure.

Long-term particulate and other air pollutants and lung function in nonsmokers.

The associations between lung function measures (spirometry and peak expiratory flow lability) and estimated 20-yr ambient concentrations of respirable particles, suspended sulfates, sulfur dioxide, ozone, and indoor particles were studied in a sample of 1,391 nonsmokers followed since 1977. Differences in air pollutants across the population were associated with decrements of lung function. An increase of 54 d/yr when particles < 10 micro(m) in diameter (PM10) exceeded 100 microg/m3 was associated with a 7.2% decrement in FEV1, as percent of predicted, in males whose parents had asthma, bronchitis, emphysema, or hay fever and with increased peak expiratory flow lability of 0.8% for all females and 0.6% for all males. An increase in mean SO4 concentration of 1.6 microg/m3 was associated with a 1.5% decrement in FEV1, as percent of predicted, in all males. An increase of 23 ppb of ozone as an 8-h average was associated with a 6.3% decrement in FEV1, as percent of predicted, in males whose parents had asthma, bronchitis, emphysema, or hay fever.

Spirometric reference equations for older adults.

The objective of this study was to develop spirometric reference equations for healthy, never-smoking, older adults. It was designed as a cross-sectional observational study consisting of 1510 Seventh Day Adventists, ages 43-79 years enrolled in a study of health effects of air pollutants. Individuals were excluded from the reference group (n = 565) for a history of current respiratory illness, smoking, or chronic respiratory disease, and for a number of 'non-respiratory' conditions which were observed in these data to be related to lower values of FEV1. Gender-specific reference equations were developed for the entire reference group and for a subset above 65 years of age (n = 312). Controlling for height and age, lung function was found to be positively related to the difference between armspan and height, and in males was found to be quadratically related to age. The predicted values for this population generally fell within the range of those of other population groups containing large numbers of adults over the age of 65 years. Individuals with lung function below the 5th percentile in this sample, however, could not be reliably identified by using the lower limits of normal predictions commonly used in North America and Europe.

Peak flow lability: association with asthma and spirometry in an older cohort.

OBJECTIVE: To determine the success rate and correlates of ambulatory peak expiratory flow (PEF) monitoring in an epidemiologic study. DESIGN: An observational survey. SETTING: Several communities in California. PARTICIPANTS: We studied 1,223 nonsmoking men and women (mean age, 66 years) from an established cohort. OUTCOME MEASURES: A standard respiratory symptoms and diagnoses questionnaire, spirometry before and after bronchodilator, and a diary of PEF recorded four times per day for 7 days at home. RESULTS: A physician diagnosis of asthma was reported in 8.6% of the women and 9.4% of the men. Of those who agreed to complete PEF diaries at home, 87% successfully provided a valid measure of PEF lability. The mean PEF lability from those with asthma was significantly higher than the others (12.0% vs 8.9% in women and 10.2% vs 8.1% in men). Independent correlates of higher PEF lability included asthma, wheezing symptoms, airways obstruction by spirometry, older age, and male gender. CONCLUSIONS: Middle-aged and elderly persons are largely successful at providing a measure of PEF lability at home. In nonsmoking adults living in California, increased PEF lability is correlated with asthma, wheezing, airways obstruction, and older age, validating its use in epidemiology studies as an index of airways hyperreactivity.

Validity of selected physical activity questions in white Seventh-day Adventists and non-Adventists.

The validity and reliability of selected physical activity questions were assessed in both Seventh-day Adventist (N = 131) and non-Adventist (N = 101) study groups. Vigorous activity questions similar to those used by others and new questions that measured moderate and light activities were included. Validation was external, comparing questionnaire data with treadmill exercise time, resting heart rate, and body mass index (kg.m-2), and internal, comparing data with other similar questions. Both Adventist and non-Adventist males showed significant age-adjusted correlations between treadmill time and a "Run-Walk-Jog Index" (R = 0.28, R = 0.48, respectively). These correlations increased substantially when restricting analysis to exercise speeds exceeding 3 mph (R = 0.39, R = 0.71, respectively). Frequency of sweating and a vigorous physical activity index also correlated significantly with treadmill time in males. Correlations were generally weaker in females. Moderate- and light-intensity questions were not correlated with physical fitness. Internal correlations R = 0.50-0.78) between the above three vigorous activity questions were significant in all groups, and correlations (R = 0.14-0.60) for light and moderate activity questions were also documented. Test-retest reliability coefficients were high for vigorous activity questions (R = 0.48-0.85) and for one set of moderate activity questions (R = 0.43-0.75). No important differences in validity and reliability were found between Adventist and non-Adventists, but the validity of vigorous activity measures was generally weaker in females.

Chronic respiratory symptoms associated with estimated long-term ambient concentrations of fine particulates less than 2.5 microns in aerodynamic diameter (PM2.5) and other air pollutants.

Seventh-Day Adventists (SDAs), nonsmokers who had resided since 1966 in the vicinity of nine airports throughout California (n = 1,868), completed a standardized respiratory symptoms questionnaire in 1977 and again in 1987. For each participant, cumulative ambient concentrations of fine particulates less than 2.5 microns (microns) in aerodynamic diameter (PM2.5) were estimated from airport visibility data. Long-term ambient concentrations of estimated PM2.5 in excess of 20 micrograms per cubic meter (micrograms/m3) were found to be associated with development of definite symptoms of chronic bronchitis between 1977 and 1987. Estimated mean concentrations of PM2.5 were associated with increasing severity of respiratory symptoms related to general airway obstructive disease, chronic bronchitis, and asthma. It was felt that the observed relationships, with the exception of the relationship between increasing severity of chronic bronchitis symptoms and PM2.5, could be due to surrogate relationships with other ambient pollutants.

Estimating fine particulates less than 2.5 microns in aerodynamic diameter (PM2.5) from airport visibility data in California.

Methods were developed for estimating fine particulates less than 2.5 microns in aerodynamic diameter (PM2.5) from airport visibility data which detected seasonality and allowed for possible site- and season-specific regressions of PM2.5 on visibility. The methods were applied to nine airports in California in order to produce estimates of PM2.5 for the years 1966-1986 based on 1,767 paired PM2.5/visibility data points where PM2.5 had been measured at a monitoring station near the airport. General F-tests indicated that site- and season-specific regression equations resulted in a statistically significant reduction in residual error. The split halves correlation for estimating PM2.5 from visibility over all areas was 0.82. The methods were used to estimate long-term concentrations of ambient PM2.5 for an epidemiological cohort of 1,868 individuals.

Estimated long-term ambient concentrations of PM10 and development of respiratory symptoms in a nonsmoking population.

Site- and season-specific regressions of particulates less than 10 mu in diameter (PM10) on total suspended particulates (TSPs) were formed throughout California during years when both were monitored. The regressions were then applied to monitored TSPs for the years 1973 to 1987, and indirect estimates of PM10 were formed. These estimates of PM10 were validated by interpolating them to other monitoring stations. The split-halves correlation between the estimated and monitored mean concentrations, obtained when both were first cumulated for a 2-y period, was .86. Indirect estimates of PM10 at monitoring stations were interpolated, by month, to zip code centroids of home and work location and were cumulated for a cohort of 3,914 California Seventh-day Adventist (SDA) nonsmokers. Multivariate analyses, adjusted for several covariates, showed statistically significant (p < .05), but small, positive associations between PM10 and development of (a) definite symptoms of overall airway obstructive disease, (b) chronic productive cough, and (c) increased severity of airway obstructive disease and asthma. The relative risk (RR) associated with 1,000 h/y (42 d) exposure to concentrations of PM10 that exceeded 100 micrograms/m3 for development of airway obstructive disease was 1.17 (95% confidence interval [CI]: 1.02, 1.33); for development of productive cough, the RR was 1.21 (CI 1.02, 1.44); and for development of asthma, the RR was 1.30 (CI, 0.97, 1.73). Stronger associations were observed for those who were exposed occupationally to dusts and fumes. The RR of developing airway obstructive disease as an adult for those who had airway obstructive disease as a child was 1.66 (CI 1.15, 2.33).

Passive smoking and chronic respiratory disease symptoms in non-smoking adults.

A prospective study was conducted to investigate the possible effects of environmental tobacco smoke (ETS) on the development of definite symptoms of airway obstructive disease (AOD) in a non-smoking adult population. In all 3914 subjects completed a standardized respiratory symptoms questionnaire in 1977 and 1987 and a computerized algorithm was used to identify new cases of definite symptoms of AOD during the follow-up period. In multivariate logistic regression models which adjusted for age, gender, income, educational level, years smoked in the past, and concentrations of ambient air pollutants, ETS exposure during childhood only was associated with a relative risk (RR) of 1.09 (95% confidence interval [CI]: 0.69-1.79), during adulthood only with an RR of 1.28 (95% CI: 0.90-1.79), and during both childhood and adult life with an RR of 1.72 (95% CI: 1.31-2.23). Results were not significantly changed when only lifetime never-smokers were used in analyses, and no interaction between ETS exposure and concentrations of ambient air pollutants was observed.

Asthma related to occupational and ambient air pollutants in nonsmokers.

We attempted to determine the association between occupational and air pollutant exposure with the development of adult asthma through the analysis of a standardized respiratory questionnaire administered to a cohort of 3914 nonsmoking adults in 1977 and again in 1987. Ambient air pollution concentrations were estimated over a 20-year period using monthly interpolations from fixed-site monitoring stations applied to zip code locations by month of residence and work site. Second-hand smoke exposure was significantly associated with the development of asthma (related risk [RR] = 1.45, confidence interval [CI] = 1.21 to 1.75). Airways obstructive disease before age 16 was related to a marked increased risk (RR = 4.24, CI = 4.03 to 4.45). An increased risk of asthma was significantly associated with increased ambient concentrations of ozone exposure in men (RR = 3.12, CI = 1.61 to 5.85).

Chronic disease associated with long-term concentrations of nitrogen dioxide.

A prospective epidemiologic cohort study of 6,000 residentially stable and non-smoking Seventh-day Adventists (SDA) in California was conducted to evaluate long-term cumulative levels of ambient nitrogen dioxide (NO2) in association with several chronic diseases. These diseases included respiratory symptoms, cancer, myocardial infarction (MI), and all natural causes mortality. Cumulative ambient concentrations of NO2 were estimated for each study subject using monthly interpolations from fixed site monitoring stations and applying these estimates to the monthly residence and work place zip code histories of study participants. In addition, a personal NO2 exposure study on a randomly selected sample of 650 people in southern California was conducted to predict total personal NO2 exposure using household and lifestyle characteristics and ambient NO2 concentrations. It was found that good predictability could be obtained (correlation coefficient between predicted and observed values = 0.79) from a model predicting personal NO2. The resulting regression equations from the personal NO2 exposure study were applied to the epidemiologic study cohort to adjust ambient concentrations of NO2.

Long-term ambient concentrations of total suspended particulates, ozone, and sulfur dioxide and respiratory symptoms in a nonsmoking population.

Seventh-day Adventist nonsmokers, who, subsequent to 1966, had resided within 8 km (5 miles) of their 1977 residence (N = 3,914), completed the National Heart and Lung Institute (NHLI) respiratory symptoms questionnaire in 1977 and again in 1987. For each participant, cumulative ambient concentrations of total suspended particulates (TSP), ozone, and sulfur dioxide (SO2) in excess of several cutoff levels were estimated by month and by interpolating ambient concentrations from state air-monitoring stations to their residential and workplace zip codes for the month. Statistically significant relationships between ambient concentrations of TSP and ozone, but not SO2, were found with several respiratory disease outcomes. Multivariate analyses adjusted for past and passive smoking and occupational exposures. Results are discussed within the context of standards setting for TSP and ozone.

Chronic respiratory disease associated with long-term ambient concentrations of sulfates and other air pollutants.

Seventh-day Adventist (SDA) non-smokers who had resided since 1966 within five miles of their 1977 residence (n = 3914) completed a standardized respiratory symptoms questionnaire in 1977 and again in 1987. For each participant, cumulative ambient concentrations from 1977 to 1987 of suspended sulfates (SO4) in excess of several cutoffs as well as mean concentrations were estimated by interpolating monthly ambient concentration statistics from state air monitoring stations to the individual's residential and workplace zip codes. There were significant associations between ambient concentrations of suspended sulfates and development of new cases of asthma, but not new cases of overall airway obstructive disease (AOD) or chronic bronchitis. Comparison of previous analyses, in this population, of respiratory disease symptoms and total suspended particulates (TSP), ozone, and sulfur dioxide (SO2), and multipollutant analyses of these pollutants with SO4, indicated these results were not due to a surrogate relationship with other air pollutants. Development of definite symptoms of AOD and chronic bronchitis was most strongly related to TSP.

A prospective study of risk for peptic ulcer disease in Seventh-Day Adventists.

Cross-sectional and prospective data were collected and analyzed to identify risk factors for the development of peptic ulcer disease in a population of 34,198 white, non-Hispanic Seventh-Day Adventists. On a life-style questionnaire administered in 1976, 3853 subjects reported ever having had a physician-diagnosed peptic ulcer for a lifetime prevalence of 13.5% for men and 11.0% for women. Odds ratios of greater than 2.0 (P less than 0.0001) were observed for use of "stronger pain relievers," current cigarette smoking, and history of rheumatism or other arthritis and coronary disease. For both sexes, lower but statistically significant odds ratios (P less than 0.05) were found for eating white bread, "snacking," ever having smoked cigarettes, low church involvement, poor dietary adherence, high blood pressure, rheumatoid arthritis, aspirin use, job frustration and dissatisfaction, having a "blue collar household," and having less education. During 3 years of follow-up, 154 incident cases of ulcer were identified. The average annual incidence was 1.7 per 1000. Multivariate adjusted relative risks were statistically significant for using stronger pain relievers (P less than 0.001), having rheumatic conditions (P = 0.006), and using aspirin (P = 0.013). These findings suggest that rheumatic disease and use of aspirin and stronger pain relievers are more important risk factors for development of peptic ulcer disease in certain populations than diet, life-style, or psychological or socioeconomic characteristics.

Estimating cumulative ambient concentrations of air pollutants: description and precision of methods used for an epidemiological study.

Methods for estimating cumulative ambient air pollution concentrations for individuals enrolled in an epidemiological cohort study are described and studied. Monthly interpolations from fixed-site monitoring stations in California to zip code centroids were used. The precision of the interpolation methods for total suspended particulates and ozone was assessed, and fixed-site monitoring stations were used in turn as receptor sites. Actual versus interpolated 2-y mean concentrations did not differ significantly and were correlated with a Pearson correlation coefficient of .78 for total suspended particulates and .87 for ozone. The impact of the change from monitoring total oxidants to ozone on oxidant/ozone cumulations was evaluated, and monthly mean concentrations for total oxidants were compared with ozone for 435 station months during which both pollutants were measured simultaneously. Average concentrations did not differ significantly and were highly correlated (r = 0.94). Exceedance frequency statistics, which averaged slightly higher for ozone than for total oxidants, were also highly correlated.