For cleaner air...

a plan to regulate the emission of particulate matter smaller than 2.5 micron (micron is one-millionth of metre), technically known as pm 2.5, is on the cards of the us Environmental Protection Agency ( epa ). The debate on implementation continues as critics and researchers battle over the issue. Very little data is available about the effects of pm 2.5 on health. In June 1997, the epa announced a new Clean Air Act standard that envisages regulation of pm2.5 emissions throughout the us . It would cost us $100 million to install the monitors in the country. The project will be fully operational only after four years, as one year is required for designing monitoring networks and three years to install the instruments across the us .

At present, only the states of California, Utah, Texas, Arizona and Alaska have started monitoring pm 2.5 emissions. The monitoring equipment, costing between us $6,000 and us $20,000, would start providing the data in 2002. These monitoring instruments are so advanced that filters retaining the particulate matter are automatically changed after 24 hours. The epa 's new annual standard sets a maximum annual limit of 15 micrograms per cubic metre (