The air in American cities is getting safer to breathe, the U.S. Environmental Protection Agency reported Thursday.
Since 1990, there has been a nearly 60 percent reduction in mercury from human sources such as coal-fired plants, a 66 percent decline in benzene, and an 84 percent fall in lead, which harms brain development in children.
About 3 million tons per year of pollutants such as particulate matter and sulfur dioxide have also been reduced from cars and trucks, the EPA said.
There has been a reduction of about 1.5 million tons per year of hazardous air pollutants such as arsenic, benzene, lead and nickel from stationary sources, and another reduction of 1.5 million tons per year of these pollutants from mobile sources, according to the agency.
These pollutants are known or suspected to cause cancer and can harm people's immune, respiratory, neurological, reproductive and developmental systems, the EPA said.
The agency's report is the final of two required under the Clean Air Act to inform Congress of progress in reducing public health risks from urban air pollution.
"This report gives everyone fighting for clean air a lot to be proud of because for more than 40 years we have been protecting Americans -- preventing illness and improving our quality of life by cutting air pollution -- all while the economy has more than tripled," EPA Administrator Gina McCarthy said in the news release.
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"But we know our work is not done yet. At the core of EPA's mission is the pursuit of environmental justice -- striving for clean air, water and healthy land for every American; and we are committed to reducing remaining pollution, especially in low-income neighborhoods," she added.