Although acknowledging that their calculations are not comprehensive, an advocacy group has concluded that at least 18 states, and possibly 14 others, are significantly undercollecting fees for permitted air pollution. In a time of tight state budgets and limited federal assistance, the shortfall in collections may be impeding state efforts to plan for, monitor, and enforce permits for many significant polluting facilities, and may result in underpayment for some of the burden on public health imposed by these facilities.
The findings are somewhat useful on their own, but also provide a template and starting point for journalists who can look into the issue in greater depth.
Under the federal Clean Air Act, states may collect a minimum of $39.48 per ton on at least the first 4,000 tons for each of five pollutants (sulfur dioxide, nitrogen oxides, volatile organic compounds, particulates, and hazardous air pollutants) emitted by sizable point sources such as power plants, refineries, chemical plants, cement kilns, and incinerators. States may also impose additional administrative and processing fees to help fund their oversight efforts.
In a report released March 7, 2007, the Environmental Integrity Project analyzed EPA or state data on three of the air pollutants (SO2, NOX, and VOCs), as well as data from selected states on the fees collected. Data on the two other pollutants (particulates and HAPs) was not consistently reported, though it may be available for your state. Data on fees collected also was not consistently and readily available for all states, although again, the data may be available to reporters who can dig through state documents.
EIP found that for the pollutants and states tracked, 18 states collected only about 30-80% of the emission fees that were legally available to them, missing out on at least $53 million per year. Contact: Eric Schaeffer,  202-296-8800 x1 or 202-263-4440. Report.  The available data also suggest that another 14 states may be similarly undercollecting.
EIP recommends that EPA should evaluate each state to see if the undercollection of fees is leaving the state short of funding to perform its required oversight functions. Schaeffer says that some crude indicators, such as inspection frequency, compliance status, quirks where hundreds of facilities are declared in compliance on the last day of the fiscal year, or statements by some states that they don't have enough funding for ambient air monitors, suggest that a number of states are underfunded. One starting point for this type of information is EPA'sECHO (Enforcement and Compliance History Online)database.  About ECHO. 
For reporters able to dig into this further, Schaeffer says EIP will share information on its methodology and the databases that are available, or may be available with further digging.