US Air Quality Fact Sheet 2021

While studies show that air quality in the US is significantly better than it was 50 years ago, the World Health Organization (WHO) is updating its standards of what acceptable air quality is.

With the WHO’s new safety guidelines of no more than 5 µg/m³ of particulate pollution, it seems that the vast majority of Americans (~97%) are at risk of unsafe levels of air pollution.

You might be thinking, “How is that possible?” This can be further clarified by understanding the Air Quality of Life Index (AQLI).

What is the AQLI?

The AQLI translates Particulate Matter 2.5 (PM2.5) pollution into terms of life expectancy. It takes the WHO’s acceptable PM guidelines and applies them to regional pollution levels to determine its effects on overall health and longevity. This index helps us understand how relative levels of PM2.5 can affect the average American’s life expectancy.

The Bad News:

  • Collectively, the US emitted 67 million tonnes of pollution into the atmosphere in 2021.
  • The average US PM2.5 pollution is around 7 µg/m³, which slightly exceeds the WHO’s safety guidelines.
  • Regions with high incidences of forest fires, such as California, have consistently high levels of PM2.5 pollution that often double or triple the recommended level.
  • Around 102 million people nationwide reside in counties with air quality concentrations above the National Ambient Air Quality Standards (NAAQS), putting them at risk of health issues related to air pollution.

The Good News:

  • By 2020, US CO2 emissions had decreased back to 1980 emission levels.
  • Air toxins have decreased by 74% from 1990 to 2017.
  • By reducing PM2.5 concentrations since 1970, many US states have gained up to 3 years in life expectancy.
  • Residents in some of California’s most polluted counties, such as Sierra County (13 µg/m³) and Mariposa County (22.6 µg/m³), can gain up to 1.7 years in life expectancy by reducing their PM2.5 concentrations to acceptable levels.
  • We have qualitative data that shows us how life expectancy can be increased with a thorough awareness of localized PM2.5 concentrations and how they measure up to the WHO’s safety guidelines.

Weather Considerations

While pollutants, such as PM2.5 concentrations, play a large role in determining regional air quality standards, weather conditions are another major force at play when it comes to air pollution. As we have seen in the case of California’s wildfires, extreme weather events can result in high levels of air pollution (e.g., 22.6 µg/m³ in Sierra County, CA).

Overall Improvements Still Warrant Caution

While the overall levels of particle pollution have drastically decreased in recent decades, there is still much diligence to be taken on a collective and individual level to ensure safety and wellbeing. One way to do this is to stay up to date on local air quality and compare it to the WHO’s current recommendations. You can easily do this with the help of PurpleAir’s air quality map.

The PurpleAir Map provides a visual of real-time air quality updates in your area. Check the PurpleAir Map to stay in the know about PM2.5 levels according to air quality monitors near you.

References

https://aqli.epic.uchicago.edu/wp-content/uploads/2021/09/USFactSheet_2022.pdf

https://www.epa.gov/air-trends/air-quality-national-summary

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