A major attempt to streamline-or, critics claim, politicize-the revision of important air-quality standards has run into trouble. One year ago, the U.S. Environmental Protection Agency (EPA) overhauled its lengthy process of updating the National Ambient Air Quality Standards (NAAQS), which have far-reaching impacts on many regulations. Some critics feared the move would allow politics to trump science by giving agency appointees more say and sidelining external scientific review.

Ariyalur, the land of fossils, is found to be embedded with rich limestone deposits. Hence around 9 cement factories have been established in and around Ariyalur. This becomes one of the source of air pollution in this area.