Robert S. Chapman

Chronic respiratory disease. In military inductees and parents of schoolchildren.

Several surveys, relating air pollution exposure to the prevalence of chronic respiratory disease, have recently been conducted by the Community Health and Environmental Surveillance program of the Environmental Protection Agency. The effects of sulfur oxides were studied in the Salt Lake Basin, Rocky Mountain smelter communities, New York City, and Chicago. In all four areas, chronic bronchitis prevalence was higher in polluted neighborhoods than in clean ones. In large urban areas, the effect of air pollution was comparable to the effect of moderate cigarette smoking. In all four areas, the effects of air pollution and of cigarette smoking were roughly additive. In Chattanooga, Tenn, no significant correlation was found between chronic bronchitis prevalence and exposure to moderate urban levels of nitrogen oxides.

Ambient particulate matter and respiratory and cardiovascular illness in adults: particle-borne transition metals and the heart-lung axis(,).

Epidemiological studies have consistently shown associations of exposure to ambient particulate matter (PM) with severe health effects, including mortality and hospitalization, in adults. From the standpoints of both relative risk and attributable risk, the public health burden of ambient PM exposure is potentially greatest in elderly adults with underlying cardiopulmonary illness. Recent experimental data suggest that PM-borne transition metals have toxicity that could be mechanistically relevant to PM-related epidemiological findings. These data may prove to be especially relevant in elderly adults with cardiopulmonary illness. At the same time, important uncertainties remain in the epidemiological and experimental databases, such that the true degree of correspondence between the two is not yet known. In our opinion, this combination of emerging experimental-epidemiological coherence and remaining uncertainty imparts high priority to further research into the health effects of PM-borne transition metals. This research should not be confined to the respiratory system. Rather, it should examine the entire heart-lung axis and should probably consider other body systems (e.g. the vascular system) as well. In this research, close interdisciplinary communication should be sustained and experimental and epidemiological approaches should be coordinated to the maximum feasible extent.

Personal and Indoor PM2.5 Exposure from Burning Solid Fuels in Vented and Unvented Stoves in a Rural Region of China with a High Incidence of Lung Cancer

The combustion of biomass and coal is the dominant source of household air pollution (HAP) in China, and contributes significantly to the total burden of disease in the Chinese population. To characterize HAP exposure related to solid fuel use and ventilation patterns, an exposure assessment study of 163 nonsmoking female heads of households enrolled from 30 villages was conducted in Xuanwei and Fuyuan, two neighboring rural counties with high incidence of lung cancer due to the burning of smoky coal (a bituminous coal, which in health evaluations is usually compared to smokeless coal—an anthracite coal available in some parts of the area). Personal and indoor 24-h PM2.5 samples were collected over two consecutive days in each household, with approximately one-third of measurements retaken in a second season. The overall geometric means (GM) of personal PM2.5 concentrations in Xuanwei and Fuyuan were 166 [Geometric Standard Deviation (GSD):2.0] and 146 (GSD:1.9) μg/m3, respectively, which were similar to the indoor PM2.5 air concentrations [GM(GSD):162 (2.1) and 136 (2.0) μg/m3, respectively]. Personal PM2.5 was moderately highly correlated with indoor PM2.5 (Spearman r = 0.70, p < 0.0001). Burning wood or plant materials (tobacco stems, corncobs etc.) resulted in the highest personal PM2.5 concentrations (GM:289 and 225 μg/m3, respectively), followed by smoky coal, and smokeless coal (GM:148 and 115 μg/m3, respectively). PM2.5 levels of vented stoves were 34–80% lower than unvented stoves and firepits across fuel types. Mixed effect models indicated that fuel type, ventilation, number of windows, season, and burning time per stove were the main factors related to personal PM2.5 exposure. Lower PM2.5 among vented stoves compared with unvented stoves and firepits is of interest as it parallels the observation of reduced risks of malignant and nonmalignant lung diseases in the region.

Tuberculosis and subsequent risk of lung cancer in Xuanwei, China†

Tobacco and indoor air pollution from smoky coal are major causes of lung cancer in rural Xuanwei County, China. Tuberculosis has been suggested to increase lung cancer risk, but data from prior studies are limited. We conducted an analysis of data from a retrospective cohort study of 42,422 farmers in Xuanwei. In 1992, interviewers administered a standardized questionnaire that included lifetime medical history, including tuberculosis. Subjects were followed from 1976, with deaths from lung cancer ascertained through 1996. We used proportional hazards regression to assess the association between tuberculosis and subsequent lung cancer mortality. Tuberculosis was reported by 246 subjects (0.6%), and 2,459 (5.8%) died from lung cancer during follow‐up. Lung cancer mortality was substantially higher in subjects with tuberculosis than in those without (25 vs. 3.1 per 1,000 person‐years). The association was especially pronounced in the first 5 years after tuberculosis diagnosis (hazard ratios [HRs] ranging 6.7–13) but remained strong 5–9.9 years (HR 3.4, 95% CI 1.3–9.1) and 10+ years (HR 3.0, 95% CI 1.3–7.3) after tuberculosis. These associations were similar among men and women and among smoky coal users (70.5% of subjects). Adjustment for demographic characteristics, lung disease and tobacco use did not affect results. In Xuanwei, China, tuberculosis is an important risk factor for lung cancer. The increased lung cancer risk, persisting years after a tuberculosis diagnosis, could reflect the effects of chronic pulmonary inflammation and scarring arising from tuberculosis. Published 2008 Wiley‐Liss, Inc.

Risk of lung cancer associated with domestic use of coal in Xuanwei, China: retrospective cohort study

Objective To estimate the risk of lung cancer associated with the use of different types of coal for household cooking and heating. Setting Xuanwei County, Yunnan Province, China. Design Retrospective cohort study (follow-up 1976-96) comparing mortality from lung cancer between lifelong users of “smoky coal” (bituminous) and “smokeless coal” (anthracite). Participants 27 310 individuals using smoky coal and 9962 individuals using smokeless coal during their entire life. Main outcome measures Primary outcomes were absolute and relative risk of death from lung cancer among users of different types of coal. Unadjusted survival analysis was used to estimate the absolute risk of lung cancer, while Cox regression models compared mortality hazards for lung cancer between smoky and smokeless coal users. Results Lung cancer mortality was substantially higher among users of smoky coal than users of smokeless coal. The absolute risks of lung cancer death before 70 years of age for men and women using smoky coal were 18% and 20%, respectively, compared with less than 0.5% among smokeless coal users of both sexes. Lung cancer alone accounted for about 40% of all deaths before age 60 among individuals using smoky coal. Compared with smokeless coal, use of smoky coal was associated with an increased risk of lung cancer death (for men, hazard ratio 36 (95% confidence interval 20 to 65); for women, 99 (37 to 266)). Conclusions In Xuanwei, the domestic use of smoky coal is associated with a substantial increase in the absolute lifetime risk of developing lung cancer and is likely to represent one of the strongest effects of environmental pollution reported for cancer risk. Use of less carcinogenic types of coal could translate to a substantial reduction of lung cancer risk.

Coal use, stove improvement, and adult pneumonia mortality in Xuanwei, China: a retrospective cohort study.

Background In Xuanwei County, China, unvented indoor coal burning is strongly associated with increased risk of lung cancer and chronic obstructive pulmonary disease. However, the impact of coal burning and stove improvement on risk of pneumonia is not clear. Methods We conducted a retrospective cohort study among all farmers born 1917 through 1951 and living in Xuanwei as of 1 January 1976. The analysis included a total of 42,422 cohort members. Follow-up identified all deaths in the cohort from 1976 through 1996. Ages at entry into and at exit from follow-up ranged from 24 to 59 years and from 25 to 80 years, respectively. The record search detected 225 deaths from pneumonia, and 32,332 (76%) were alive as of 31 December 1996. We constructed multivariable Cox models (time variable = age) to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results Use of coal, especially smokeless coal, was positively associated with pneumonia mortality. Annual tonnage and lifetime duration of smoky and smokeless coal use were positively associated with pneumonia mortality. Stove improvement was associated with a 50% reduction in pneumonia deaths (smoky coal users: HR, 0.521; 95% CI, 0.340–0.798; smokeless coal users: HR, 0.449; 95% CI, 0.215–0.937). Conclusions Our analysis is the first to suggest that indoor air pollution from unvented coal burning is an important risk factor for pneumonia death in adults and that improving ventilation by installing a chimney is an effective measure to decrease it.

Long-term ambient air pollution levels in four Chinese cities: inter-city and intra-city concentration gradients for epidemiological studies.

The field data collection of an air pollution epidemiologic study was carried out from 1993 to 1996 in four Chinese cities of Lanzhou, Chongqing, Wuhan, and Guangzhou. In each city, an urban district and a suburban district were selected. Ambient concentrations of total suspended particles (TSP), size-fractionated particulate matter including PM2.5, PM2.5–10, and PM10, sulfur dioxide (SO2), and oxides of nitrogen (NOx) were measured in these districts. The results indicate the presence of wide inter-city and intra-city gradients in long-term ambient levels of these measured pollutants. Across the eight districts, the 1993–1996 4-year means of TSP, SO2, and NOx ranged from 198 to 659 μg/m3, from 14.6 to 331 μg/m3, and from 31.5 to 239 μg/m3, respectively, and the 1995–1996 2-year means of PM2.5, PM2.5–10, and PM10 ranged from 51.5 to 142 μg/m3, from 29.2 to 107 μg/m3, and from 80.7 to 232 μg/m3, respectively. These pollution ranges substantially extended the upper end of the pollution ranges of previous air pollution epidemiologic studies conducted in North America and Europe. In each district, significant correlations among the measured pollutants were observed for daily concentrations. However, the gradient patterns in long-term means of different pollutants were different across the eight districts. (e.g., PM2.5–10 and TSP were highest in the Lanzhou urban district, PM2.5 and PM10 were highest in the Guangzhou urban district, SO2 was highest in the Chongqing urban district, and NOx was highest in the Guangzhou urban district). In general, seasonal variations were present in the ambient concentrations with high levels often occurring in winter months. The eight districts may be classified into four district clusters based on integrated levels of all measured pollutants. These features of the ambient air pollution have important implications for epidemiological studies and may provide unique opportunities to study exposure–effects relationships in the four Chinese cities.

Variation in lung cancer risk by smoky coal subtype in Xuanwei, China

Lung cancer rates in Xuanwei County have been among the highest in China for both males and females and have been causally associated with exposure to indoor smoky (bituminous) coal emissions that contain very high levels of polycyclic aromatic hydrocarbons. There are numerous coal mines across the County. Although lung cancer risk is strongly associated with the use of smoky coal as a whole, variation in risk by smoky coal subtype has not been characterized as yet. We conducted a population‐based case–control study of 498 lung cancer cases and 498 controls, individually matched to case subjects on age (±2 years) and sex to examine risk by coal subtype. Odds ratios (ORs) and 95% confidence intervals (CIs) for coal subtype were calculated by conditional logistic regression, adjusting for potential confounders. Overall, smoky coal use was positively and statistically significantly associated with lung cancer risk, when compared with the use of smokeless coal or wood (OR = 7.7, 95% CI = 4.5–13.3). Furthermore, there was a marked heterogeneity in risk estimates for specific subtypes of smoky coal (test for heterogeneity: p = 5.17 × 10−10). Estimates were highest for coal of the Laibin (OR = 24.8, 95% CI = 12.4–49.6) and Longtan (OR = 11.6, 95% CI = 5.0–27.2) coal types and lower for coal from other subtypes. These findings strongly suggest that in Xuanwei and elsewhere, the carcinogenic potential of coal combustion products can exhibit substantial local variation by specific coal source. Published 2008 Wiley‐Liss, Inc.

Effects of Air Pollution on Children's Respiratory Health in Three Chinese Cities

Abstract During the winter of 1988–1989, parents of 2,789 elementary-school students completed standardized questionnaires. The students were 5–14 y of age and were from three urban districts and one suburban district of three large Chinese cities. The 4-y average ambient levels of total suspended particles in the three cities differed greatly during the period 1985–1988: Lanzhou, 1,067 μmlg/m3; urban Wuhan, 406 μmlg/m3; Guangzhou, 296 μmlg/m3; and suburban Wuhan, 191 μmlg/m3. The authors constructed unconditional logistic-regression models to calculate odds ratios and 95% confidence intervals for prevalences of several respiratory symptoms and illnesses, adjusted for district, use of coal in the home, and parental smoking status. There was a positive and significant association between total suspended particle levels and the adjusted odds ratios for cough, phlegm, hospitalization for diseases, and pneumonia. This association was derived from only the 1,784 urban children and, therefore, the authors were unable to extrapolate it to the suburban children. The results also indicated that parental smoking status was associated with cough and phlegm, and use of coal in the home was associated only with cough prevalence (α = 0.05).

Ambient Particulate Matter and Lung Function Growth in Chinese Children

Background: Exposure to particulate matter (PM) has been associated with deficits in lung function growth among children in Western countries. However, few studies have explored this association in developing countries, where PM levels are often substantially higher. Methods: Children (n = 3273) 6–12 years of age were recruited from 8 schools in 4 Chinese cities. The lung function parameters of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were measured using computerized spirometers twice a year for up to 3 years (1993–1996). Dichotomous samplers placed in each schoolyard were used to measure PM2.5 and PM10 (PM with diameter ⩽2.5 &mgr;m and ⩽10 &mgr;m, respectively). Multivariable generalized estimating equations were used to examine the association between the quarterly average PM levels and lung function growth during the period of follow-up. Results: Annual average PM2.5 and PM10 levels in the 4 cities ranged from 57 to 158 &mgr;g/m3 and 95 to 268 &mgr;g/m3, respectively. In multivariable models, an increase of 10 &mgr;g/m3 of PM2.5 was associated with decreases of 2.7 mL FEV1 (95% confidence interval = −3.5 to −2.0), 3.5 mL FVC (−4.3 to −2.7), 1.4 mL/year FEV1 growth (−1.8 to −0.9), and 1.5 mL/year FVC growth (−2.0 to −1.0). Similar results were seen with PM10 exposure. Conclusions: Exposure to ambient particulate matter was associated with decreased growth in lung function among Chinese children.