On their final day to do so, residents submitted comments -- some lengthy -- to Indiana regulators on BP's controversial air permit.

The comment period on the permit necessary for BP's $3.8 billion refinery expansion closed Monday, with groups including Chicago contacting the Indiana Department of Environmental Management.

Representing itself and six other groups, the Natural Resources Defense Council sent a 35-page letter to IDEM condemning the permit for, among other things, not including into BP's estimates emissions from three new structures that burn off gas.

The consortium submitted an analysis from a California-based environmental consultant, who called it "more than wishful thinking" that the refinery would never turn on the structures, a large source of emissions.

In response to some comments already submitted, IDEM is re-examining the issue, spokesman Rob Elstro said. IDEM is trying to determine how it will deal with the concerns and will include any changes or adjustments in a permit addendum when it is issued, Elstro said.

Under the proposed permit, BP would emit lower amounts of four pollutants but would increase emissions of sulfur dioxide, particulate matter and lead.

BP officials have touted a predicted 15 percent production increase, in spite of a projected 7 percent decline in overall air emissions, with the permit.

The permit does not deal with an expected 30 percent to 40 percent -- or an annual 1.5 million to 2 million tons -- increase in carbon dioxide, a greenhouse gas.

The NRDC said the permit ignores a Massachusetts-based U.S. Supreme Court case that said carbon dioxide is a pollutant regulated under the Clean Air Act.

IDEM doesn't have carbon dioxide rules and therefore does not have the legal authority to regulate it, Elstro said.

In a joint letter to IDEM, Chicago and the Illinois attorney general questioned portions of the permit, including why it excludes a chemical analysis of the Canadian crude oil the plant will refine and certain emission data from recent years.

Some community leaders, contractors and union members have spoken out in favor of the permit, most recently at a hearing in Hammond.

As of last week, IDEM had received more than 150 comments, the majority of which have supported the permit, Elstro said.

IDEM could take three to six weeks to decide on the permit, depending on the volume and complexity of the comments, he said.