Long-term Trends
The EPA provides consistent raw data from 1980 to 2020 showing very rapid improvements from 1980-2000 and continued, but slower improvements in the last 20 years on 7 measures of air quality. For each item, reductions from 1980-2020 and from 2010-2020 are listed.
Carbon monoxide: -81%, -12%
Lead: N/A, -86%
NO2: -64%, -21%
Ozone: -33%, -10%
Particulate Matter 10 (medium): -26% since 1990, +9%
PM 2.5 (fine): -41% since 2000, -18%
Sulphur Dioxide: -94%, -74%.
More details at this website:
National Air Quality: Status and Trends of Key Air Pollutants | US EPA
Decade by decade data.
Air Quality – National Summary | National Air Quality: Status and Trends of Key Air Pollutants | US EPA
The EPA publishes an annual report/web page to summarize results. In addition to the colorful graphs, its shows sources of pollution and describes the effects of individual pollutants. It provides statistics that normalize pollution measures against GDP which has grown greatly across 40 years, highlighting the even greater achievements by that measure. It shows pollution by city. It details EPA program areas and improvements. It notes that measures of more than 100 “toxic” air pollutants are down (but not zero). It shows that annual “unhealthy days” in the nation’s 35 largest cities have fallen by two-thirds, from 2,100 to 700/year between 2000 and 2015. It shows that “visibility” in scenic areas continues to improve. This report provides significant extra detail in an easy to drill down format.
Our Nation’s Air 2021 (epa.gov)
Our Nation’s Air – Air Quality Improves as America Grows (epa.gov)
Comparisons
Based on the fine particulate measure, the US ranks 84th best of 106 countries (top 20%).
World’s Most Polluted Countries in 2020 – PM2.5 Ranking | AirVisual (iqair.com)
US state measures vary quite widely. Indiana ranks 45th, 46th and 48th by 3 measures.
State Pollution Rankings | US News Best States
Air Quality By State 2021 (worldpopulationreview.com)
see national air pollution tab.
Explore Air Pollution in the United States | 2020 Annual Report | AHR (americashealthrankings.org)
Recent Concerns
The particulate matter measures have historically had the slowest reductions of the 7 measures. The medium particle (10 microns or less) rate increased between 2010 and 2020. The fine particles measure stopped falling at the end of the decade.
w26381.pdf (nber.org)
Bad Air Quality Plagues California, Washington, Oregon Cities : NPR
The Trump administration has loosened regulations, reduced funding and attempted to limit the ability of states to set tougher standards than those at the federal level.
What is the Trump administration’s track record on the environment? (brookings.edu)
NACAA2021PresidentialTransitionDocument-01152021.pdf (4cleanair.org)
Opportunities for Improvement
Interest groups, like the American Lung Association, portray the data to show that the glass is half-empty. The ALA focuses on the two weakest measures (fine particles and ozone). They drill down to daily peak events rather than average annual rates. They drill down to the city or county level to highlight the lower performers. They take the national quality standards and construct a “grading system”, so that the worst “F” cities and their scores can be emphasized. They use these results to show how many people are negatively effected by poor air quality. They emphasize that most of these cities are in the west and southwest. They point out that minority groups are disproportionately impacted by pollution. They link extreme heat and wildfires as causes of recent pauses in progress, noting that global warming is the underlying driver.
Key Findings | State of the Air | American Lung Association
Air quality in US dramatically worse, says new ‘State of the Air’ report – CNN
A recent United Nations article evaluates the last 50 years in the US, highlighting the improvements summarized above. The article emphasizes the health costs of poor air quality and the economic benefits of improved air quality. The “tone” and the “title” are negative. The report highlights the recent uptick in particle measures. It points to the lack of a decrease in CO2/greenhouse gases. It notes that the US is one of the top 10 worst air polluters ranked by number of deaths (not per capita). Finally, it says that the US EPA also agrees that there are major problems.
The United States Clean Air Act turns 50: is the air any better half a century later? (unep.org)
Overview of Greenhouse Gases | Greenhouse Gas (GHG) Emissions | US EPA
Pollution and Health Metrics: Pollution by country data and rankings (gahp.net)
The EPA website lists 4 challenges.
- Meeting increased science/health based standards.
- Climate change
- Reducing toxic pollutants
- Protecting the ozone layer
Air Pollution: Current and Future Challenges | Overview of the Clean Air Act and Air Pollution | US EPA
Summary
Like many public policy issues, especially environmental issues, there are competing ways to assess the current situation. The big picture data clearly shows ongoing improvements across 40 years. The fine particulate matter measure stands out as one that may be threatened by climate and fire issues. Federal, state and local regulators, together with businesses, governments, not-for-profits and individuals have taken steps to improve air quality and appear likely to continue in this direction.
On the other hand, air pollution above certain levels, in specific locations, especially for toxic substances, even for short periods of time, does have negative health and economic impacts. There are opportunities for improvement. The U.S. measures are just average compared with similar highly developed economies.
The world, including the US, has made great strides in reducing the emission of gases that threaten the ozone layer. However, CO2 levels in the US in 2020 are the same as in 1990. While US GDP has increased significantly since 1990, so we are more environmentally “efficient”, that does not matter when trying to globally reduce “greenhouse gases”.
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