To fight Twin Cities smog, give up that lawn mower, diesel buses?

Unless Twin Cities residents get serious about giving up old lawn mowers, wood-burning stoves and diesel engines, the state of Minnesota could face costs of up to $240 million a year to meet tough new federal clean air requirements.

For years the Twin Cities region has bumped up against the federal ceiling for damaging pollutants such as soot and ground ozone. This year the U.S. Environmental Protection Agency is expected to tighten some of those standards — and that could force the state to produce a costly plan to reduce air pollution, according to the Environmental Initiative, an umbrella group of industry, government and environmental organizations in Minnesota.

The good news, according to a report prepared for release this week, is that air pollution from large single sources such as power plants and factories has dropped dramatically, thanks to new regulations and technologies.

But now the problem is — everyone else. Homeowners. Commuters. Landscapers. Small-business owners. School buses. Back-yard fires.

"That creates a whole different challenge," said David Thornton, assistant commissioner of the Minnesota Pollution Control Agency (MPCA).

In an effort to avoid the EPA's expensive regulatory crackdown, the Environmental Initiative has spent the past year trying to find consensus among pollution regulators, industry officials and representatives from clean air groups.

At a conference on Thursday they are expected to unveil their best ideas — from buying back old engines to educational campaigns.

"That's been an effective way to motivate," said Mike Harley, the group's executive director. "That's a real number and real price tag."

In its annual State of the Air report released this week, the American Lung Association said the region that includes Minneapolis, St. Paul and St. Cloud ranked 42nd out of 235 metro areas in levels of short-term particle pollution — an improvement from 36th last year. Based on annual averages for small-particle pollution, the Twin Cities was in the middle of the pack, ranking 116th out of 220, also an improvement from last year's ranking of 104th.

Thornton said Minnesota has violated the federal standard for daily particulate levels a number of times, but regulatory action kicks in only if averages exceed federal limits three years in a row.

"We are OK now," he said. "But we could flip back and forth in any given year."

However, the EPA is now considering new ozone rules, and if they come in at the low end of the spectrum, "we are going to be in real trouble, or close to being in real trouble," Thornton said.

In the Twin Cities, primary air pollution problems are soot and other small particulate matter, and ozone that develops close to the ground.

On any given day, half the tiny particles that float invisibly in the air come from burning wood and vehicle engines. Most of the rest comes from gases that react with ammonia in the atmosphere. But they produce particles that are small enough to get deep into the lungs and even into the bloodstream. They aggravate asthma, cause other lung problems and even heart attacks.

Ground ozone is created when chemical pollutants react to heat and sunlight. Along with small particles, it's a major component of smog, and can also cause serious lung problems. The MPCA estimates that the annual economic value of premature deaths caused by air pollution in Minnesota is about $30 billion, about $8 million per death. The annual economic value of all other health impacts of particulate and ozone pollution in Minnesota is about $400 million, officials said.

Those who participated in the Environmental Initiative's Clean Air Dialogue said identifying the problems was easy. Figuring out how to solve them, however, was not.

Thornton said the group wrestled with wood burning, including back-yard fires. "It's used as a form of recreation and enjoyment." he said. "There is a real tug and pull between what we know and what we like."

That's why the recommendations will be based on voluntary actions. They include improving the urban forest to filter dirty air, a rebate program for old leaf blowers and lawn mowers, incentives for fleets to switch to alternative fuels like natural gas, getting old cars off the road, and model city ordinances to manage wood burning systems.

Then, the question is how to pay for it. Gov. Mark Dayton included $900,000 for clean air initiatives in the MPCA budget, but that's still under debate at the Legislature. By next year the group should have some concrete proposals for lawmakers, because Harley said, "We need money."