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U.S. cities with the dirtiest air

  • U.S. cities with the dirtiest air

    Poor air quality can rapidly deteriorate human health; it can lead to respiratory issues, which can, in turn, shorten lifespans. This is why it is vital for communities to monitor air pollution and make strides toward reducing it for the safety of its residents. To help identify poor-quality air, the Environmental Protection Agency has created National Ambient Air Quality standards. The two most relevant standards are 150 micrograms of pollutants per cubic meter of air over a 24-hour period for coarse particulate matter (PM10) and 12 micrograms of pollutants for fine particulate matter (PM2.5).

    For this article, Stacker researched the 50 American cities with the worst quality of air. This ranking was based on 2018 statistics and took into account 193 United States cities that the EPA reported their PM10 values for. Twenty-one of the cities included in this list came from just the state of California alone.

    The air quality was ranked according to the amount of particulate matter (PM) between 2.5 and 10 micrometers in the air. The higher the amount of particulate matter, the dirtier the quality of air. In the case of cities with equal amounts of particulate matter, the city with dirtier air was determined by which city had the highest particulate matter on the second dirtiest day. Cities that had an annual mean amount of particulate matter smaller than 2.5 micrometers were not included in this ranking. The second-highest days were also included to rule out unusually low outliers. 

    One important note about the data is that rankings were determined by typical or average values. Exceptionally high or low values were regarded as outliers and not used to quantify the mean average particulate matter upon which the rankings were based. We also included other explainers as to factors, such as industries and climate factors, that could also account for low air quality in these cities.

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  • #50. Chico, CA

    - Average coarse particulate matter (PM10) in 2018: 25 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 81 μg/m^3 (46% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 13.7 μg/m^3 (14% above EPA standard)

    A top cause of air pollution in the Chico area comes from the smoke from wildfires common in Northern California, in which temperature inversions trap particulate matter and make it hard for it to escape. Chico became a haven for those impacted by the Camp Fire of November 2018. Its population numbers have since skyrocketed, with reports from residents of traffic jams, housing shortages, and overly crowded public places, all likely to increase overall pollution in the area. 

  • #49. Santa Maria-Santa Barbara, CA

    - Average coarse particulate matter (PM10) in 2018: 25 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 103 μg/m^3 (31% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 8.6 μg/m^3 (28% below EPA standard)

    A large air pollution contributor in Santa Barbara comes from ash stirred up in the air in the aftermath of wildfires in surrounding areas. Local government agency Santa Barbara County Air Pollution Control District aims to help protect the environment and residents from the impact of air pollution, with on-staff experts in meteorology, engineering, and environmental science. 

  • #48. Laramie, WY

    - Average coarse particulate matter (PM10) in 2018: 25 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 113 μg/m^3 (25% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 5 μg/m^3 (58% below EPA standard)

    Wildfires, such as the Badger Creek Wildfire in 2018, have contributed significantly to the smoke pollution in the air. The Department of Atmospheric Science at the University of Wyoming has put up air quality monitors on top of the UW Engineering building to provide an accurate air quality index for Laramie.

  • #47. Redding, CA

    - Average coarse particulate matter (PM10) in 2018: 25 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 137 μg/m^3 (9% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: Not available

    A major contributor to air pollution in Redding is climate change and its effects on the ozone layer. Eight cities in California, including the Redding-Red Bluff area, saw an increase in unhealthy ozone days (throughout 2014–2016), according to the American Lung Association's 2018 State of the Air report. The study awarded Redding-Red Bluff an F grade, making it one of the smoggiest places in the country. 

  • #46. San Diego-Carlsbad, CA

    - Average coarse particulate matter (PM10) in 2018: 26 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 54 μg/m^3 (64% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 10 μg/m^3 (17% below EPA standard)

    The heat waves and wildfires common in San Diego have played a major role in increasingly unhealthy ozone levels. The American Lung Association explains that part of the  problem is that the mountains in the area trap the polluted air. While the group found from 2014–2016 there was a 42% increase in the average number of smoggy days per year over 2012–2014, the average is still significantly down from 1998–2000, which averaged 95 annual smoggy days. 

  • #45. Indianapolis-Carmel-Anderson, IN

    - Average coarse particulate matter (PM10) in 2018: 26 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 55 μg/m^3 (63% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 10.9 μg/m^3 (9% below EPA standard)

    A major factor for pollution is the lack of public transportation, which fuels high usage of cars and high emissions into the air. Another notable contributor is the coal-fired power plants that are carried by winds to other parts of Indiana as well.

  • #44. Sierra Vista-Douglas, AZ

    - Average coarse particulate matter (PM10) in 2018: 26 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 88 μg/m^3 (41% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 5.6 μg/m^3 (53% below EPA standard)

    The main contributor to air pollution in Sierra Vista is the high-ozone count in the atmosphere. Out of 228 metro areas, the American Lung Association ranked Sierra Vista #123 for high-ozone days, but the metro surprisingly tied for first place for the country's cleanest metro area in regards to 24-hour particle pollution. 

  • #43. Kalispell, MT

    - Average coarse particulate matter (PM10) in 2018: 26 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 99 μg/m^3 (34% below EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 7.5 μg/m^3 (38% below EPA standard)

    High traffic, especially during the wintertime, causes the amount of particulate matter in the air to increase. Temperature inversions are also another contributor to poor air quality in this area.

  • #42. Rock Springs, WY

    - Average coarse particulate matter (PM10) in 2018: 26 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 193 μg/m^3 (29% above EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 5.7 μg/m^3 (53% below EPA standard)

    A significant source of pollution comes from the oil and gas industries in the area and from the trona mines. Wyoming's Department of Environmental Quality has installed ambient air quality monitors in Rock Springs.

  • #41. Bishop, CA

    - Average coarse particulate matter (PM10) in 2018: 26 μg/m^3
    - Second-highest average coarse particulate matter (PM10) over a 24-hour period: 353 μg/m^3 (135% above EPA standard)
    - Average fine particulate matter (PM2.5) in 2018: 7.4 μg/m^3 (38% below EPA standard)

    The goal of government agency Great Basin Unified Air Pollution Control District is to help protect the environment and residents of Alpine, Mono, and Inyo Counties, the last of which Bishop is located within. GBUAPCD monitors multiple air quality cameras in the region in order to make sure the region is meeting federal and state air quality standards.