President Obama's decision to scrap tighter smog standards is a reprieve for businesses and drivers in the Portland, Salem, Eugene and Medford areas, which would have likely been pushed into violations of federal clean air law by the new rules.

But

estimates indicate the stricter rule would have cut asthma attacks in those areas, as well as reducing premature deaths. Oregon environmental regulators

, noting that Oregon's asthma rates are well above the national average.

The ground-level ozone standard proposed by the EPA would have reduced allowable levels of ground-level ozone, the main ingredient of smog, by up to 20 percent.

The president

after several EPA delays in issuing it, citing concerns about the cost to business and regulatory uncertainty.

In Oregon, the new rules could have led to expanded vehicle emissions testing around cities, more pollution control at factories and power plants and expanded retrofits of diesel engines to reduce emissions of nitrogen oxides, a key component of ozone.

Ground-level ozone results when car exhaust, chemical solvents, power plant pollution and industrial emissions react to sunlight. It's worst on hot days with stagnant air.

The new "primary" standard would have reduced allowable levels of ground-level ozone75 parts per billion of ozone over an eight-hour period to between 60 to 70 parts per billion.

At 60 ppb, the new standard would yield health benefits from $35 billion to $100 billion a year by 2020, the EPA estimated, eliminating 58,000 cases of aggravated asthma and from 4,000 to 12,000 premature deaths that year. Annual costs would run from $52 billion to $90 billion by 2020, the agency said.

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