our ancestors seemed to have taken air quality more seriously than we do today; for example, in ancient Indian villages, the location of kilns was compulsorily some distance from human habitation. Formal smoke control regulations in several Indian towns date from as far back as the middle of the 19th century. However, the first scientific and regular monitoring of air quality was started only in 1967 by the Nagpur-based NEERI (National Environment Engineering Research Institute). neeri started regular monitoring of air quality at three stations - one each in a prominent industrial, residential and commercial area - in 10 major Indian cities.The parameters monitored included dust-fall, sulphation rate (rate of sulphur production) and emissions of sulphur dioxide (so₂), oxides of nitrogen (no_x) and suspended particulate matter (spm). spm was further analysed for heavy metals, carcinogens and other specific chemical pollutants. It should be noted, however, that data available represents the years from the mid-"60s to early "90s. It is, therefore, shocking to observe that the deterioration in air quality had set in long ago and the trend only seems to be getting worse.

Emissions: a veritable spread
so₂ emissions were considered the most critical pollutants in the neeri study during the 1960s-80s review period. so₂ causes bronchial irritation in humans and damage to vegetation even at low concentrations. Higher so₂ concentrations could result in acid rains. Mumbai, with its high degree of industrialisation, large number of vehicles and rather adverse topography and meteorology, reported a few incidents of acid rain, and the industrial area of Chamber and its environs earned the epithet "gas-chamber of Mumbai". so₂ concentrations in ambient air in the 10 cities monitored by neeri shows an apparent decline in five of them after 1980 (See table: Sulphur spurts). This perhaps can be attributed to liquid petroleum gas replacing wood, coal and kerosene as a cooking fuel. But among the 10 cities surveyed, Delhi and Kochi showed a significant rising trend in so₂ emissions after 1980, essentially caused by large, unplanned and uncontrolled industrial and urban growth. In the southern cities of Bangalore and Mysore in Karnataka, based on surveys conducted by the Karnataka state pollution control board, the annual average concentrations of so₂ were not of significant concern at less than 30