Administration rejects calls to toughen existing smog limits

WASHINGTON — The Trump administration declined to impose stricter limits on smog-forming pollutants Wednesday, saying national ozone standards set in 2015 are sufficient. Public- health advocates had pressed for lower levels of ozone, arguing the hazardous gas disproportionately affects the most vulnerable Americans.

Formed when chemicals from power plants, cars and industrial operations are exposed to heat and sunlight, ozone is linked to an array of illnesses including childhood asthma and lung disease.

The Clean Air Act requires the Environmental Protection Agency to set air pollution standards every five years to a level that protects public health. Under the Obama administration in 2015, the EPA l owered the standard from 75 parts per billion to 70 parts per billion, averaged over an eight- hour period.

EPA Administrator Andrew Wheeler said Wednesday the decision to keep the current ozone st andards followed a careful review of the best available science regarding its health effects, noting that pollution levels have sharply declined since the creation of the agency in 1970.

“Air quality has made progress in this country for decades and the last several years have seen spectacular improvements benefiting the health of millions of Americans,” he said.

Members of the EPA’S Clean Air Scientific Advisory Committee, all of whom have been appointed under President Donald Trump, endorsed the idea of keeping the National Ambient Air Quality Standards for ozone at the current level.

But many public- health experts argued it should be lowered to 60 parts per billion, given the growing scientific evidence that points to the heavier pollution burden carried by low- income and communities of color and ozone’s impact on at- risk groups.

The problem is made worse by a warming planet, said Paul Billings, senior vice president for advocacy at the American Lung Association. Higher temperatures make ozone more likely to form.