Respiratory health of brickworkers in Cape Town, South Africa. Symptoms, signs and pulmonary function abnormalities.

The respiratory health of 268 brickworkers in five brickworks was investigated by means of a questionnaire, a physical examination, and pulmonary function testing. The prevalence of respiratory symptoms ranged from 7% for chronic bronchitis to 52% for morning cough to 27% for both chest tightness and wheeze and 9% for dyspnea at effort. A stepwise logistic regression analysis showed the symptoms to be significantly predicted by combinations of smoking and exposure to dust, while a multiple linear regression showed an effect of dust exposure on forced vital capacity and forced expiratory volume in 1 s but no smoking effect. Smoking generally had less of an effect than dust and predicted early/mild symptoms only.