The State of the Air 2019
Too many cities across the nation experienced more ozone and more particle pollution in 2015-2017. Many reached or tied their highest levels ever.
The "State of the Air" 2019 found that, in 2015-2017, more cities had high days of ozone and short-term particle pollution compared to 2014-2016 and many cities measured increased levels of year-round particle pollution.
The "State of the Air" 2019 report shows that too many cities across the nation increased the number of days when particle pollution, often called "soot," soared to often record-breaking levels. More cities suffered from higher numbers of days when ground-level ozone, also known as "smog," reached unhealthy levels. Many cities saw their year-round levels of particle pollution increase as well.
The "State of the Air" 2019 report adds to the evidence that a changing climate is making it harder to protect human health. The three years covered in this report ranked as the hottest years on record globally. High ozone days and spikes in particle pollution zoomed, putting millions more people at risk and adding challenges to the work cities are doing across the nation to clean up.
The 2019 report—the 20th annual release—uses the most recent quality-assured air pollution data, collected by the federal, state and local governments and tribes in 2015, 2016 and 2017. The "State of the Air" 2019 report looks at levels of ozone and particle pollution found in official monitoring sites across the United States in 2015, 2016 and 2017. For comparison, the "State of the Air" 2018report covered data from 2014, 2015 and 2016.1 The report uses the most current quality-assured nationwide data available for these analyses.
The report examines particle pollution (PM2.5) in two separate ways: averaged year-round (annual average) and short-term levels (24-hour). For both ozone and short-term particle pollution, the analysis uses a weighted average number of days that allows recognition of places with higher levels of pollution. For the year-round particle pollution rankings, the report uses averages calculated and reported by the U.S. Environmental Protection Agency (EPA).
The "State of the Air" 2019 found that ozone and short-term particle pollution worsened in many cities in 2015-2017, compared to 2014-2016. Even levels of year-round particle pollution increased in some cities.
More than four in 10 Americans, approximately 43.3 percent of the population, live in counties that have monitored unhealthy ozone and/or particle pollution. The number of people exposed to unhealthy air increased to nearly 141.1 million. That represents an increase from the past two reports: higher than the 133.9 million in the 2018 report (covering 2014-2016) and the 125 million in the 2017 report (covering 2013-2015). Close to 20.2 million people, or 6.2 percent, live in 12 counties with unhealthful levels for all three measures.
More than 4 in 10 people live where the air is unhealthy.
Still, progress continues, thanks to the tools in the Clean Air Act. While this is a significant spike in areas with unhealthy levels of ozone and particle pollution, it remains still far below the 166 million in the years covered in the 2016 report (2012-2014).
Los Angeles remains the city with the worst ozone pollution as it has for 19 years of the 20-year history of the report. Fresno-Madera-Hanford, CA returned to the most-polluted slot for year-round particle pollution, while Bakersfield, CA, maintains its rank as the city with the worst short-term particle pollution.
More must be done to address climate change and to protect communities from the growing risks to public health. This year's report covered the three warmest years in modern history and demonstrates the increased risk of harm from air pollution that comes despite other protective measures being in place. The Clean Air Act must remain intact and enforced to enable the nation to continue to protect all Americans from the dangers of air pollution. This law has driven improvements in air quality for nearly 50 years, improvements that the "State of the Air" 2019 continues to document. Figure 1 from EPA shows that since 1970, the air has gotten cleaner while the population, the economy, energy use and miles driven increased greatly.2 We must ensure that the Clean Air Act’s tools remain in place, funded, and followed.
The "State of the Air" 2019 report shows, again, that climate change makes it harder to protect human health. This year’s report shows the spike in high ozone days and in unhealthy particle pollution episodes driven by wildfires. While most of the nation has much cleaner air quality than even a decade ago, too many cities suffered increased ozone from the increased temperature 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. 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.
As climate change continues, cleaning up these pollutants will become ever more challenging.
The Clean Air Act must remain intact and enforced to enable the nation to continue to protect all Americans from the dangers of air pollution. At its core, the Clean Air Act protects public health and has driven improvements in air quality for nearly 50 years, as shown in Figure 1. Since 2000, the "State of the Air" reports have also documented these improvements, as shown in trend charts for counties and cities available at www.stateoftheair.org. That progress is not certain to continue, as some in Congress seek to remove or weaken that law, and as the administration seeks to repeal or reverse the safeguards in place to enforce the law.
- A complete discussion of the sources of data and the methodology is included in Methodology.
- U.S. Environmental Protection Agency. Air Trends National Summary, 2019. Sources are: CO2 emissions estimate through 2016 (Source: 2015 US Greenhouse Gas Inventory Report); Gross Domestic Product: Bureau of Economic Analysis; Vehicle Miles Traveled: Federal Highway Administration; Population: Census Bureau, Energy Consumption: Dept. of Energy, Energy Information Administration; Aggregate Emissions: EPA's Air Pollutant Emissions Trends Data.