The Pittsburgh City Council passed a "clean construction" law more than 18 months ago. But, to date, no dozers, diggers or dump trucks have had to comply.
Called the Clean Air Act of 2010, the law focused on construction sites that received public dollars. If the development's budget was larger than $2.5 million and it received at least $250,000 in public subsidies, it would have to retrofit a percentage of its diesel equipment.
Regulations for the ordinance haven't been finalized, making it unenforceable.
Supporters of the ordinance have cried foul.
"If we truly want to be the most livable city, we have to contend with our air pollution," said Rachel Filippini, the executive director of the Group Against Smog and Pollution, known as GASP. "And one way to do that is to clean up construction vehicles."
GASP was part of a coalition of health, environmental, faith, industry and labor organizations that helped draft the legislation. It is similar to "clean construction" laws that have sprouted across the country, and it is modeled after New York City's version.
The Environmental Protection Agency has set standards for new diesel engines, but it's the old engines that produce what's known as "dirty diesel" fumes.
Dirty diesel exhaust contains tiny particles of soot, also known as black carbon. The smallest of these particles can go straight into the bloodstream and are linked to cancer, asthma and stroke.
Children, the elderly and people with chronic lung and heart conditions are among the most vulnerable to dirty diesel's impact. And workers who operate diesel equipment are the first to breathe the emissions.
Pittsburgh City Councilman Bill Peduto, who was the main sponsor of the ordinance and is running for mayor in the May 21 primary, sent copies of New York City's regulations to Pittsburgh's Law Department.
Meetings concerning the regulations to implement the ordinance have been going on for more than a year, according to Mr. Peduto's office.
However, the regulations have not been finalized, said Daniel Regan, Pittsburgh's solicitor.
Mr. Regan said they are waiting to hear from several city departments. He had no estimate of when the regulations might be in place.
"We weren't involved, nor were we asked to be involved, in drafting the legislation," Mr. Regan said, adding that they thought it was important for the sponsors to review it.
Doug Anderson, the deputy city controller whose inspectors will be in charge of enforcing the retrofitting requirements, said his inspectors haven't been trained.
Councilwoman Natalia Rudiak, co-sponsor of the ordinance, said she hopes the regulations are written as soon as possible. Ms. Rudiak, representing neighborhoods in the South Hills, is running for re-election in the May primary.
"Until it's implemented, it's just words on a page," she said.