"Limited data and unreliable estimates on air pollution from oil and natural gas production is hindering the Environmental Protection Agency's efforts to police the drilling boom, the agency's internal watchdog said in a report released Thursday."

"Inspector General Arthur Elkins Jr. said the EPA has failed to directly measure emissions from some pieces of equipment and processes, and some estimates it does have are of 'questionable quality.'

'With limited data, human health risks are uncertain, states may design incorrect or ineffective emission control strategies, and EPA's decisions about regulating industry may be misinformed,' Elkins said.

The EPA, under President Barack Obama, has stepped up regulation of natural gas drilling, which has been booming thanks to hydraulic fracturing, or fracking. About 25,000 wells a year are being fracked, a process in which water, chemicals and sand are injected at high pressure underground to release trapped natural gas."

Dina Cappiello reports for the Associated Press February 21, 2013. [2]