Earning perfect scores were Reps. Patrice Arent, Joel Briscoe and Carol Moss, and Sens. Patricia Jones and Karen Mayne, all Democrats representing Salt Lake County communities, and Sen. Evan Vickers, R-Cedar City.
Three Republicans earned a 0 percent score: Sen. Aaron Osmond, South Jordan; Sen. Daniel Thatcher, West Valley City; and Rep. Jim Bird, West Jordan.
"We acknowledge the limitations of this study: the relatively small number of bills in the study, a problem exacerbated by the fact that for the bills that didn't pass, one house or the other didn't even vote on it," said CleanAirNow! activist Carl Ingwell.
For example, the Senate last year killed a bill that would have lifted the state's ban on wood-burning outdoor boilers, without a floor vote.
Thatcher and Osmond never had a chance to win a point by voting against HB394, which cleared the House in a 59-12 vote. Bird did not cast a vote.
Kanab Republican Rep. Mike Noel, who received a 20 percent score, sponsored the bill.
Thatcher and Osmond voted yes on SB21, which limited the size and authority of grass-roots boards that guide the Department of Environmental Quality, including the Air Quality Board. They also voted no on HB96, which renewed tax credits for those who drive natural-gas vehicles.
More than 67 percent of senators and 61 percent of representatives got grades of "D" or worse in the CleanAirNow! analysis.
"This study was not a great way to assess the commitment of legislators in their resolve to ensure clean air," Osmond said in an email. "In my case, five of my 10 votes were never cast."
The senator said he supports public education on air quality, as well as state regulation, and noted he supported some of the clean-air measures but got no credit.
"We have to do something," Osmond said, "while balancing the need to protect our personal liberties with the health and safety of society."
Air-quality town hall Wednesday
The Tribune's Jennifer Napier-Pearce will moderate a town-hall discussion on Utah's air quality challenges with a panel of experts at 7 p.m. on Wednesday, Jan. 29, at the Salt Lake City Main Library, 210 E. 400 South.
The discussion will be broadcast live on KCPW 88.3/105.3 FM and at sltrib.com. You can submit questions in advance by sending an email to firstname.lastname@example.org.