Respiratory illness in factory and office workers

Time-series studies of particulate matter

Studies of air pollution and human health have evolved from descriptive studies of the early phenomena of large increases in adverse health effects following extreme air pollution episodes to time-series analyses based on the use of sophisticated regression models. In fact, advanced statistical methods are necessary to address the challenges inherent in the detection of a relatively small pollution risk in the presence of potential confounders. This paper reviews the history, methods, and findings of the time-series studies estimating health risks associated with short-term exposure to particulate matter (PM), though much of the discussion is applicable to epidemiological studies of air pollution in general. We review the critical role of epidemiological studies in setting regulatory standards and the history of PM epidemiology and time-series analysis. We also summarize recent time-series results and conclude with a discussion of current and future directions of time-series analysis of particulates, including research on mortality displacement and the resolution of results from cohort and time-series studies.

Effect of SO2 exposure on nasal mucociliary clearance in intact chickens

The time required for mucociliary clearance from the chicken nasal turbinate and from the maxillary sinus was investigated in individual animals by using a newly designed plastic holder for the experimental animals. Determined in this way were: 1) the effect of SO2 exposure on sinus and turbinate clearance time, 2) the effect of the nerve blocking drugs atropine, scopolamine, reserpine, and propranolol on turbinate clearance time, and 3) the effect of these nerve blockers on clearance rates in chickens exposed to SO2. Turbinate mucociliary clearance was measured at 5 intervals per day, during 1 to 7 hr after exposure, for 7 consecutive days. Sinus clearance time was measured twice daily 1 to 4 hr after exposure. Turbinate clearance time in birds exposed to 6 ppm, and sinus clearance time in birds exposed to 40 ppm intermittently for 2 consecutive days both increased strikingly as a direct effect of SO2 exposure. However, continuous exposure to 6 ppm of SO2 during 16 hr per day for 7 consecutive days produced double peaks of increased turbinate clearance time with intervening recovery periods, suggesting an intranasal mucociliary homeostatic response. In individual animals, 26 of 35 animals (75%) exposed to 5 ppm, and 5 of 10 animals (50%) exposed to 20 ppm continuously during 16 hr per day for 7 consecutive days showed the same patterns. Reserpine and propranolol, which are sympatholytic agents, produced decelerated intranasal transport rates. Atropine and scopolamine, which are parasympatholytic agents, did not affect clearance rates. These nerve blockers, however, blocked the biphasic recovery pattern due to SO2 exposure. This blocking effect was statistically significant for atropine and reserpine 1 hr after injection.

The incidence and severity of acute respiratory illness in families exposed to different levels of air pollution, New York metropolitan area, 1971-1972

The incidence and severity of acute respiratory disease was studied in families in three New York communities with different ambient levels of SO2 and particulate air pollution. Upper, lower, and total respiratory disease rates in fathers, mothers, and school children tended to be higher in the communities with higher pollution levels. Similar higher rates, however, were not observed among preschool children. Regression analyses were used to adjust rates for socioeconomic status, parental smoking, chronic bronchitis in parents, and possible indoor pollution resulting from the use of a gas stove for cooking. After these adjustments the community differences were still significant (P less than .01), for schoolchildren. The indoor pollution related to gas stoves was a significant covariate among children. The effects of smoking were inconsistent. It was not possible to attribute the higher rates observed to any specific pollutant, since both SO2 and particulate matter levels were higher in the high pollution communities, nor was it possible to attribute the excesses to current levels of exposure or to a residual effect of previous higher exposure concentrations. The fact that young children did not follow the pattern suggests the latter. It was concluded, however, that current or previous exposures to the complexity of air pollutants in New York City was at least partially responsible for increased incidences of acute respiratory disease.

A double-blind cross-over trial of trimethoprim and sulphamethoxazole in chronic bronchitis

A double-blind cross-over trial comparing trimethoprim-sulphamethoxazole with sulphamethoxazole in patients with chronic bronchitis in their usual state of health showed that the combination was more effective in reducing the volume and purulence of the sputum. Although the patients preferred treatment with the combination, there was no objective improvement in respiratory function. There was a significant incidence of side effects.

An annual cycle in the ventilatory capacity of men with pneumoconiosis and of normal subjects

The forced expiratory volume over 0·75 second (F.E.V._0·75) was measured monthly for 3 years in 28 working ex-miners with pneumoconiosis and for one year in 17 normal laboratory workers. A significant annual cyclical variation of 0·044 litre amplitude was found in the ex-miners, with minimum and maximum values on 2 February and 3 August respectively. In the normal subjects the amplitude of the change was about 0·10 litre. An attempt was made to relate the changes in ventilatory capacity in the ex-miners to those in environmental temperature, relative and absolute humidity, and barometric pressure. Dry-bulb temperature showed a cyclical pattern in phase with that of ventilatory capacity, but there was no strong correlation between the deviations from these cyclical components, which would have been desirable to support a causal relation between change of temperature and of ventilatory capacity. There was no definite evidence of a relationship between any other of the environmental parameters and ventilatory capacity. Fourteen of the ex-miners had purulent sputum at intervals but remained at work. Immediately after these attacks the ventilatory capacity was not lower than before, but those having attacks showed a greater annual decline in their F.E.V._0·75. We think that the cyclical variation in ventilatory capacity is not directly caused by the environmental conditions measured, or by sputum purulence, but could represent an intrinsic biological rhythm which is perhaps modified by the environmental temperature.