Year-round particle pollution levels are continuing to drop across the nation, maintaining a long-term shift. Between 2014 to 2016, most cities experienced fewer days of spikes in this pollution — caused by power plants or car exhaust, for example — according to the American Lung Association’s new 2018 “State of the Air” report.

The cleaner air trend in the United States, however, is threatened by a Congress and presidency that seem intent on rolling back gains made in air pollution over the past 45 years.

“Unfortunately, some in Congress seek changes to the Clean Air Act that would dismantle key provisions of the law and threaten the progress made over nearly five decades,” the authors of the report, released Wednesday, explained. Furthermore, the Trump administration’s proposed budget for 2019 “claims to put a priority on ‘improving air quality’ but would cut EPA funding for that work significantly,” according to the report.

Primary particle pollutants are emitted directly from sources such as construction sites, unpaved roads, smokestacks, or fires. Other particles, known as secondary particles, are emitted from power plants, factories, and automobiles. These secondary particles make up most of the fine particle pollution in the United States.


Overall, the number of Americans exposed to unhealthy levels of air pollution has increased to almost 134 million people according to this year’s report. This is higher than the 125 million people exposed to air pollution identified in the association’s 2017 report, which covers the years between 2013 and 2015.

The health risks of air pollution are significant, with asthma and lung cancer two of the top problems experienced by people who live in high-pollution areas. Many people also are at great risk from smog and particulate matter, especially if they already have chronic health problems such as cardiovascular disease or diabetes.

Environmental Protection Agency (EPA) Administrator Scott Pruitt, however, has signaled his agency will restrict the research that it will allow scientists to consider in their decision making, and plans to eliminate major scientific research that supports strong clean air standards.

“The Clean Air Act has saved lives and improved lung health for nearly 50 years,” American Lung Association National President and CEO Harold Wimmer said Wednesday in a statement. “We call on President Trump, EPA Administrator Scott Pruitt and members of Congress to fully fund, implement and enforce the Clean Air Act for all pollutants — including those that drive climate change and make it harder to achieve healthy air for all.”


This is the 19th year that the American Lung Association has released its clean air report. The association obtained the data on air quality from the EPA’s Air Quality System, formerly called the Aerometric Information Retrieval System database. It also contracted with Allen Lefohn of A.S.L. & Associates to study certain ozone and particulate matter information.

The researchers found that on a county-by-county basis, more than four in 10 people, or 41.4 percent, in the United States live in counties that have unhealthy levels of either ozone or particle pollution.

Ozone pollution worsened significantly in the 2014-2016 period, according to the report. Many cities across the nation experienced more days when ground-level ozone, also known as “smog,” reached dangerous levels, including most of the cities with the worst ozone problems.

Increased heat in 2016 likely drove this increase in ozone. Warmer temperatures stimulate the reactions in the atmosphere that cause ozone to form, and 2016 saw the second warmest temperatures on record in the United States.

Los Angeles topped the list again for the most unhealthy air days in the nation. The city has held this distinction for all but one of the 19 annual clean air reports issued by the American Lung Association.

NEW: More than 4 in 10 Americans live in counties with unhealthy levels of #ozone or particle #pollution https://t.co/viZps4WKx3 #StateOfTheAir pic.twitter.com/fYe8uCO1ca — American Lung Assoc. (@LungAssociation) April 18, 2018

In fact, 11 of the 25 most polluted cities in the nation are located in California despite the many policies implemented by the state to improve its air quality. For example, the state has threatened to move forward on its own if the federal government weakens the federal standards for vehicle fuel efficiency.


Meanwhile, the Southwest continues to fill most of the remaining slots. Only six of the 25 most polluted cities are located east of the Mississippi River: New York City, Philadelphia, Hartford, Connecticut, Chicago, Sheboygan, Wisconsin, and Atlanta.

The American Lung Association has also reported on elevated levels of unhealthy ozone in places where the construction of oil and gas production wells, processing plants, transmission pipelines and storage units have increased. These activities emit harmful gases, including methane, volatile organic compounds and other pollutants.

With its rebirth as an industrial center from the growth of the natural gas industry in Pennsylvania, the city of Pittsburgh ranked in the top 25 most polluted cities from year-round particulate pollution.

“Despite this, EPA has recently proposed steps to weaken or roll back health-protective standards the Agency had adopted in 2016 to reduce harmful emissions of these gases from new and modified sources within the oil and natural gas industry,” the report said.

The EPA even backed off collecting data from the oil and gas industry about the location and size of their facilities. Under President Obama, the EPA requested information from the industry about emissions from these existing sources. The industry objected, and in March 2017, the EPA, under the leadership of Scott Pruitt, withdrew its request for updated information on their facilities.

Source: American Lung Association's 2018 "State of the Air" report

The “State of the Air” report said six cities qualified as the nation’s cleanest cities. To rank as one of the nation’s cleanest, each city must experience no high ozone or high particle pollution days and must rank among the 25 cities with the lowest year-round particle pollution levels. The cities on the list were Bellingham, Washington; Burlington-South Burlington, Vermont; Casper, Wyoming; Honolulu, Hawaii; Palm Bay-Melbourne-Titusville, Florida; and Wilmington, North Carolina.

The report emphasized that climate change will make it harder to clean up certain air pollutants. While most of the nation has much cleaner air quality than even a decade ago, many cities suffer increased ozone from rising temperatures and continued high particle pollution from wildfires driven by changing rain patterns.

“As climate change continues, cleaning up these pollutants will become ever more challenging,” the report said. “Climate change poses many threats to human health, including worsened air quality and extreme weather events. The nation must work to reduce emissions that worsen climate.”