Symptoms suggestive of chronic bronchitis or chronic productive cough were found in 29.0% of 100 workers exposed to flour dust in a flour mill, 26.0% presenting with chronic cough and 29.0% with phlegm. In the control group, the prevalence of chronic cough and phlegm was only 6.6% in each category. While 22.0% of the workers complained of chest tightness on exposure, and 18.0% developed symptoms and signs of bronchial asthma, only 3.3% of the controls complained of chest tightness and 3.3% of asthma. Respiratory measurements before and after the working shift showed a significant drop (p less than .001) in the forced expiratory volume in 1 sec (FEV1.0) and forced vital capacity (FVC) in the exposed group. Fifty-eight percent of the exposed workers experienced a drop in FEV1.0 and FVC measurements. A positive skin reaction to wheat flour extract was recorded among 31% of the exposed workers vs. 10% of the controls. The prevalence of other associated allergic symptoms was 17.0% and 19.0% for sinusitis and conjunctivitis, respectively; in the unexposed group, the prevalence of the same symptoms ranged between 3.3% and 6.6%. A strong association was revealed between exposure to grain and flour dusts and the prevalence of respiratory and allergic disorders.

This study has been carried out to investigate the prevalence of byssinosis and other respiratory symptoms among 311 Sudanese workers in different sections of the Khartoum Weaving and Spinning Company. The prevalence of byssinosis was 67% among blowers, 40% in carders and draw-frame workers, 42% in simplex workers and 37% in ring-frame workers. The prevalence of chronic bronchitis ranged between 29 to 47% in all groups. A significant fall in FEV1 was recorded in carders and draw- and ring-frame workers. There was also a statistically significant decrease in FVC after shift in all groups except in the ring-frame group. The result of the present study revealed that the prevalence of byssinosis was very high in mills processing coarse cotton. Application of control measures and the early detection of exposure effects will reduce the prevalence of byssinosis and other respiratory impairments.