Fluctuations Of Daily Air Pollution Levels And Respiratory Symptoms By Health Diary In 4 Communities From The Prospective Health Survey, Bombay

As part of 3 year study of health morbidity in relation to air pollution around Bombay, of 4129 subjects 2232 were chosen to record daily health diary. By end of third year 1338 subjects kept it regularly; major causes for lapses were change of residence and noncooperation. There were no significant difference in the trends of each area over 3 years except in the 'urban medium' area where with a decline in the pollution, the morbidity decreased. Generally, the 'urban high' area showed the highest SO2 and S.P.M. levels. The levels of NO2 were highest in 1978 but in later 2 years these were similar to the 'urban medium' area. The latter site had lower SO2 but similar S.P.M. levels. The 'urban low' area showed low SO2, moderate NO2 and high S.P.M. levels. The rural area had only high S.P.M levels. The prevalences for common colds were highest in the 'urban medium' area around 30-55 percent; those for cough were 15-45% and dyspnoea 2-7 percent. The respective values for the 'urban high' area were, 15-35% (colds), 8-19% (cough) and 1-8% (dyspnoea). The values for the 'urban low' area were 5-20% (colds), 4-19% (cough) and up to 3% (dyspnoea). The prevalences for the rural subjects were very low. Generally the worst month was August, then September, May and June. The prevalences for common colds were worst in monsoon months. All the urban areas had high prevalences for diarrhoea. The trends revealed a significantly high morbidity around days with higher SO2 pollution in all urban - areas. The monthly trends revealed that the fluctuations in colds and cough corresponded broadly to S.P.M. levels in 1978, 1979 but to SO2 in 1980 (when S.P.M. levels were lower). There was no relationship with the duration of a particular symptom but to the intensity as reflected by need for medical treatment. It is concluded that in Bombay, the health morbidity fluctuates to a significant degree with air pollutant fluctuations.