Trends in background air pollution parameters over India

The Background Air Pollution Monitoring Network (BAPMoN) data from ten stations in the Indian region for the period 1973–1990, has been used to determine the background trends. Falling pH and increasing turbidity trends have been noticed in all but one of the stations. The post 1982 epoch has witnessed fall in annual mean pH at Vishakhapatnam, Allahabad, Pune and Nagpur though the reduction of mean values are not statistically significant at 5% level of confidence. Frequency distributions of the values of turbidity coefficient B(500 nm) for the epochs 1974–1980, 1981–1985 and 1986–1990 are also presented here. The trend of atmospheric burden is seen to be positive upto the second epoch and stable subsequently. The source identification for chemical constituents of rainwater has been examined by carrying out principal component analysis and using BAPMoN rain chemistry data collected in the entire period of 1974–1988.