Population Booms and Pollution Woes: Air Quality in America's 5th Most-Populous City

Maricopa county is one of the most populous in the U.S., and in 2017 grew by over 74,000 people, more than any other county in the nation.¹ Much of that gain went to the Phoenix-Mesa-Scottsdale metropolitan area, which takes the title of 11th largest metro area. Phoenix proper was given the distinction of fastest-growing city in the U.S. as well as claiming the 5th spot in the list of the most populous cities. That growth is great for the economy, local businesses and startups, and cultural enrichment. Such an influx of people also means more consumption, of energy, water, and fuel. It’s not surprising that the air quality in densely packed cities is worse than in less-populated areas, and the same can be said of Phoenix. The Environment Arizona Research and Policy Center released a report this past summer on the status of air quality across the U.S., and the Phoenix-Mesa-Scottsdale metro area had a whopping 110 days in 2016 during which the air pollution was at or above “moderate” levels according to the EPA standard.² That number surpasses metro areas with much larger populations, including New York and Chicago. As population numbers grow, so too does pollution.

In December 2017, The American Lung Association, American Public Health Association, Sierra Club, and other bodies concerned with the air quality of major population centers filed suit against Scott Pruitt, in his official capacity as EPA Administrator, for failing to meet the EPA deadline to designate air quality standards.³ In re Ozone Designation Litigation, was decided in a pretrial motion for summary judgment in favor of the plaintiffs (ALA, et al.) in March of this year by the U.S. District Court for the Northern District of California.⁴ The ALA (and co-plaintiffs) alleged that the Administrator’s, and therefore EPA’s, “failure to meet the deadline that Congress prescribed violates the Clean Air Act” and sought declaratory relief and an order for the Administrator to issue designations with all haste.⁵ Plaintiffs’ counsel noted that the designations had not been made for areas throughout the nation which are most affected by ground-level ozone—highly populated cities and regions.⁶ The court found that there was no dispute of material facts—the EPA did not dispute that it had failed to issue designations by the deadline.⁷ The court’s relief was to order the EPA to “promulgate by April 30, 2018 designations for all areas”.⁸ This was a major win for environmental advocates as EPA designations must be set for clean-up requirements to take effect. With national implications, this is especially important as urban centers such as Phoenix become more populated. In an article for the Journal of Environmental Health and Preventive Medicine, two researchers, Bingheng Chen and Haidong Kan, note the inverse relationship between economic development and related activities—including population growth and air quality.⁹ It will become increasingly important to monitor ground-level ozone levels as population levels rise and become increasingly clustered in the coming years.

There is some good news, as a report from the American Lung Association released this year notes that air quality across the nation has improved over recent decades.¹⁰ In Arizona, air pollution has decreased by 62% since 1990, though the state’s population increased over 80 during that period. Though this is encouraging news, progress must continue, as noted by the number of moderate or worse air quality days. With continued implementation of air quality standards—possible through the litigation mentioned above and continued vigilance—and an increasing shift towards renewable energy and fuel-efficient or electric vehicles, Phoenix and the surrounding metro area will be able to continue growing without fear of air quality-related repercussions.


¹ Jessica Boehm, Maricopa County Is Fastest-Growing In Nation, According to U.S. Census Data, ᴀᴢᴄᴇɴᴛʀᴀʟ (March 22, 2018, 10:52 a.m. MT), https://www.azcentral.com/story/news/local/phoenix/2018/03/22/maricopa-county-fastest-growing-county-nation-according-u-s-census-data-phoenix-mesa-scottsdale/449043002/.

² Elizabeth Ridlington and Christy Leavitt, Eɴᴠɪʀᴏɴᴍᴇɴᴛ Aʀɪᴢᴏɴᴀ, Trouble in the Air: Millions of Americans Breathe Polluted Air at 5 (Summer 2018), https://environmentarizonacenter.org/sites/environment/files/reports/Trouble%20in%20the%20Air%20vAZ.pdf.

³ Eᴀʀᴛʜᴊᴜsᴛɪᴄᴇ, Court Orders EPA To Move Forward With Implementing Strengthened Smog Standard (March 12, 2018), https://earthjustice.org/news/press/2018/court-orders-epa-to-move-forward-with-implementing-strengthened-smog-standard.

In re Ozone Designation Litig., 286 F. Supp. 3d 1082 (N.D. Cal. 2018).

⁵ Id.

⁶ Id.

⁷ Id.


⁹ Bingheng Chen and Haidong Kan, Air Pollution and Population Health: A Global Challenge 13 Eɴᴠᴛʟ. Hᴇᴀʟᴛʜ & Pʀᴇᴠᴇɴᴛɪᴠᴇ Mᴇᴅ. 94 at 94 (2008), https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2698272/.

¹⁰ Aᴍ. Lᴜɴɢ Ass'ɴ, State of the Air 2018 (2018), https://www.lung.org/assets/documents/healthy-air/state-of-the-air/sota-2018-full.pdf.

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