Cross-State Air Pollution Update


This rule is a health-protective, science-based update to EPA’s Cross-State Air Pollution Rule, which reduces harmful air pollution that travels across state lines.

S.J. Res. 21 is sponsored by U.S. Sen. Pat Toomey (R-Penn.).


Did you know that some of the pollution in the air we breathe comes from hundreds of miles away? This “secondhand smog” can put health at risk in downwind communities.

The U.S. Environmental Protection Agency’s (EPA) Cross-State Air Pollution Rule (CSAPR) targets air pollution that crosses state lines and worsens air quality in downwind states. CSAPR requires certain states, all in the eastern half of the U.S., to reduce power plant emissions that contribute to high ozone and particle pollution in downwind states.

Under the Clean Air Act, EPA sets health-based limits on ozone, particle pollution, and other outdoor air pollutants that harm human health. Ozone and particle pollution can cause asthma attacks, heart problems, and even premature death, and certain groups, like children and seniors, are at greater risk. (Learn more here about the health impacts of these pollutants.) EPA is also required to periodically review the science on these pollutants, because new research often shows that they are more harmful than previously thought. If the current research shows that a limit is not strong enough to protect public health, EPA has to update it.

CSAPR is designed to be updated to reflect these new air pollution limits. In September 2016, EPA finalized an update to CSAPR bringing it in line with ozone standards set in 2008. The update is projected to further reduce ozone-forming emissions from power plants in 22 states.

EPA estimates that the update, along with other changes underway in the power sector, will result in benefits worth up to $880 million, which is a maximum benefit-to-cost ratio of 13 to 1, and will prevent:

  • More than 67,000 asthma attacks
  • Almost 56,000 days of missed work and school
  • More than 240 hospital and emergency room visits
  • Up to 60 premature deaths

The air we breathe doesn’t respect state boundaries. Air pollution can blow from hundreds of miles away into states and cities that can do nothing by themselves to stop it. Breathing air pollution that blows across state lines exposes millions to secondhand smog. Congress recognized this, and included a “good neighbor” provision in the Clean Air Act that gives states the help of EPA to get the upwind pollution cleaned up to keep the secondhand smog away.

Unhealthy levels of air pollution can harm anyone, but some are at greater risk than others. Children; the elderly; people with lung diseases like asthma, COPD, and lung cancer; people with heart disease; people who work or exercise outdoors; and people with low incomes are all more vulnerable to health problems from ozone and particle pollution.

Thanks to the Clean Air Act, the nation has made enormous progress in cleaning up these harmful air pollutants, including pollution that blows across state lines. But with more than 4 in 10 Americans still living where pollution levels are dangerous to breathe, now is not the time to roll back or block clean air protections.


There has been good progress when it comes to protecting the public from pollution blowing across state lines, but Senator Pat Toomey introduced a resolution to block a life-saving update to the Cross-State Air Pollution rule.


Janice Nolen, American Lung Association,, (202) 715-3444


Coming soon.