M. B. Schenker

Daily air pollution effects on children's respiratory symptoms and peak expiratory flow

To identify acute respiratory health effects associated with air pollution due to coal combustion, a subgroup of elementary school-aged children was selected from a large cross-sectional study and followed daily for eight months. Children were selected to obtain three equal-sized groups: one without respiratory symptoms, one with symptoms of persistent wheeze, and one with cough or phlegm production but without persistent wheeze. Parents completed a daily diary of symptoms from which illness constellations of upper respiratory illness (URI) and lower respiratory illness (LRI) and the symptom of wheeze were derived. Peak expiratory flow rate (PEFR) was measured daily for nine consecutive weeks during the eight-month study period. Maximum hourly concentrations of sulfur dioxide, nitrogen dioxide, ozone, and coefficient of haze for each 24-hour period, as well as minimum hourly temperature, were correlated with daily URI, LRI, wheeze, and PEFR using multiple regression models adjusting for illness occurrence or level of PEFR on the immediately preceding day. Respiratory illness on the preceding day was the most important predictor of current illness. A drop in temperature was associated with increased URI and LRI but not with increased wheeze or with a decrease in level of PEFR. No air pollutant was strongly associated with respiratory illness or with level of PEFR, either in the group of children as a whole, or in either of the symptomatic subgroups; the pollutant concentrations observed, however, were uniformly lower than current ambient air quality standards. Moreover, since exposure estimation based on monitoring of ambient air likely results in misclassification of the true exposure, the negative findings of this study must be interpreted cautiously.

Diesel exhaust - an occupational carcinogen?

The existence of polycyclic aromatic hydrocarbons (PAH) in the paniculate phase of diesel engine exhaust has raised concern about a carcinogenic effect in workers exposed to exhaust from diesel engines. Some of the PAH are carcinogenic following inhalation by experimental animals and are associated with excess cancer mortality in some occupational exposures. Studies of occupational exposure to diesel exhaust show concentrations of PAH are above ambient levels but below the very high levels in occupations with demonstrated excess cancer mortality. A critical review of the epidemiologic evidence on the carcinogenicity of workplace exposure to diesel engine exhaust is suggestive of a carcinogenic effect but the existing data are sparse and contradictory. Further epidemiologic studies of this question are needed.

Risk factors for childhood respiratory disease: analysis of pulmonary function

Four thousand elementary-school-age children from a rural area of western Pennsylvania participated in a cross-sectional survey that consisted of a standardized respiratory questionnaire completed by their parents and spirometric testing at school. Spirographic tracings were digitized to obtain the FVC, FEV0.75, FEF25-75, Vmax75, and Vmax90, which were standardized for height, age, and sex for the subsequent analyses. Independent associations of potential risk factors with the standardized pulmonary function measures were evaluated with multiple regression techniques. Asthma, persistent wheeze, and parental smoking habits, especially those of the mothers, were associated with lower flow rates. The effect of parental smoking was primarily due to smoking by the mother and was stronger in girls. In female children of currently smoking mothers, FEF25-75 was 96% of predicted, Vmax75 was 95% of predicted, and Vmax90 was 92% of predicted; each flow measure was 98% of predicted in male children of smoking mothers. Prolonged hospitalization at birth was independently associated with lower FEV0.75 and flow rates. Low socioeconomic status was associated with lower FVC and FEV0.75. Neither current gas stove use nor a history of severe chest illness before 2 yr of age were independently associated with lower levels of pulmonary function.

Diesel exposure and mortality among railway workers: results of a pilot study.

A pilot study of the mortality of railway workers was undertaken to evaluate the feasibility of studying the association of exposure to diesel exhaust and cause specific mortality. The cohort consisted of 2519 white male subjects aged 45-64 with at least 10 years of railway service by 1967. Subjects were selected on the basis of job classification, and cause specific mortality was ascertained for subjects who died (n = 501) up to 1979. The total follow up period was 28.4 (X 1000) person-years. The standardised mortality ratio (SMR) for the cohort, based on United States national rates, was 87 (95% confidence limits 80, 95), and there were no significant differences from expected number of deaths for any specific neoplasm. The directly standardised rate ratio for respiratory cancer among diesel exposed subjects relative to unexposed subjects was 1.42 +/- 0.50 (means +/- SE). A proportional hazards model was consistent with the findings of the standardised rate ratio, but in neither analysis was the increased risk of respiratory cancer in diesel exposed subjects statistically significant.