The agency said it wants to limit ozone pollution to between 65 to 70 parts per billion of ozone in the air, a range the EPA said is based on extensive scientific data about the harmful effects of smog. The EPA said it will take comment on a level “as low as 60 parts per billion.” Those limits are below the current level — set at 75 parts per billion — which was set in 2008 under the then-President George W. Bush administration.

“Bringing ozone pollution standards in line with the latest science will clean up our air, improve access to crucial air quality information, and protect those most at-risk,” said EPA Administrator Gina McCarthy in a statement.

Ozone in the air is an oxidant that can irritate the air ways and cause coughing, a burning sensation, shortness of breath, and other lung diseases. Children, people with lung disease, older adults, and those who are active outdoors are most sensitive to ozone, according to the EPA. Ozone, or smog, is particularly likely to reach unhealthy levels on hot sunny days in cities. The agency on Wednesday said the proposed standards would also help low income and minority families who are “most likely to suffer from asthma or to live in communities that are overburdened by pollution.”

The EPA said its scientists examined numerous studies as it considered the most recent review of the ozone standards, including more than 1,000 new studies published since the last update.

The proposal is expected to reignite a spat between businesses and environmental groups, Wall Street Journal reported. Back in 2011, the EPA estimated that the proposed standard — then set at the toughest level the agency had yet considered — could cost $90 billion a year to utilities and other businesses. President Barack Obama delayed issuing it, WSJ reports.

Seemingly anticipating some resistance on costs, the EPA statement on Wednesday said every dollar invested to meet clean air standards would return “up to three dollars in health benefits.” For example, the EPA estimated that health benefits gained from fewer asthma attacks, premature deaths and other health effects would be valued at $19 billion to $38 billion annually in 2025 for a standard 65 parts per billion. Annual costs were estimated at $15 billion for that same standard.

The EPA didn’t disclose how it determined those estimates.

The agency, which is seeking public comments on the proposal and will hold three public hearings, expects to issue final ozone standards by next October.