The World health Organization (WHO) which rates only mega cities of the world has rated Delhi the fourth most polluted city ion the world. However compared to other cities in India, Delhi is not at the top of the list of polluted cities. Our country has several pollution hotspots. The recent release from the Central Pollution Control Board (CPCB), Parivesh, January 2003 states that Ahmedabad’s air is most noxious flowed by Kanpur, Solapur and Lucknow with small particulate levels (PM10) 3-4 times the standard of 60 microgram per cubic meter (mg/m3 ). The report has ranked 29 cities according to Respirable Particulate Matter (RSPM) levels recorded during the year 2000. This report thus confirms the fact that Indian cities show high particulate pollution with 14 cities hitting critical levels.
Nitrogen dioxide levels in most major cities are generally close to the acceptable annual standard of 60 mg/m3 . However sharp increases have been noticed in a few cities with heavy vehicular traffic and density as in a few locations in Kolkata and Delhi indicating stronger impact of traffic. The CPCB indicates vehicles as one of the predominant sources of air pollution. How-ever the impact of hard measures implemented in Delhi over the last few years such as introduction of Euro II standards, lowering the sul-phur content in fuel to 500 ppm and implementing Compressed Natural Gas program has succeeded in improving the quality of air. Rapid urbanization of smaller cities especially those situated near the big commercial centers have an enormous increase in traffic load espe-cially in the most polluted segment such as two and three wheelers and diesel vehicles combined with poor quality fuel contribute to the deterio rating air quality in a big way. It is alarming to note that residential locations in India are fast outpacing industrial locations in air pollution implying that vehicular fumes are responsible for this trend. The Supreme Court’s order of April 5, 2002 has directed the Central Government for an action plan forother polluted cities. Absence of any local initiatives for action and delay in air pollution control mea-sures will only make the situation worse.
The Supreme Court also played a vital role protecting the Taj Mahal. Being exposed to sulphur dioxide and suspended particulate matter, the Taj had contracted ‘marble cancer’, a fungal growth that corroded its surface giving it a yellowish tinge. The SPM deposits blackened it. Shri MC Mehta an environmental lawyer filed a public interest litigation in 1984 expressing concern over the havoc the polluting units in Agra were wreaking on the Taj Mahal. Twelve years later the Supreme Court ordered 292 industries in the vicinity to either adopt pollution control measures or shut down. It also made it manda-tory for these units to either switch over to eco-friendly fuels like natural gas or shift out of the area.
Air quality monitoring
India does not presently have a well established system of monitoring air pollution. When air quality monitoring began in India in the late 1960s planners focused only on a few pollutants namely sulphur dioxide, nitrogen oxides and suspended particulate matter. Other pollutants such as carbon monoxide and lead were monitored only on a limited scale. The threat from other air toxins such as benzene, ozone, other small particulates is not known as these are not monitored at all. A database on ambient air quality in Indian cities has been prepared by the monitoring networks of the National Environ-mental Engineering Research Institute (NEERI), Nagpur. The Central Pollution Control Board (CPCB) initiated its own national Ambient Air Quality Monitoring (NAAQM) program in 1985.
Data to the NAAQM is supplied by the respec-tive state pollution control boards, which is then transmitted to the CPCB. Experts feel that the present air quality-monitoring network cannot capture the true profile of urban air pollution due to the lack of adequate monitoring stations. Moreover critical toxins have still not been in-cluded in the list of pollutants to be monitored.