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|7||West Valley City, Utah|
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(local time)SEE WORLD AQI RANKING
12:39, Dec 1
live AQI index
|Air pollution level||Air quality index||Main pollutant|
|Good|| 37 US AQI||PM2.5|
PM2.5 concentration in Hartford is currently 1.8 times the WHO annual air quality guideline value
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|Tuesday, Nov 28|
Good 10 AQI US
|Wednesday, Nov 29|
Good 44 AQI US
|Thursday, Nov 30|
Good 46 AQI US
Good 37 AQI US
|Saturday, Dec 2|
Good 46 AQI US
|Sunday, Dec 3|
Good 50 AQI US
|Monday, Dec 4|
Good 28 AQI US
|Tuesday, Dec 5|
Good 8 AQI US
|Wednesday, Dec 6|
Good 10 AQI US
|Thursday, Dec 7|
Good 9 AQI US
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Hartford air quality index averaged a value of 32, “good,” in 2019, showing a slight improvement from its AQI score of 34 in 2018. While air quality generally poses little to no health risks, unhealthy ozone days are not uncommon in the warmer summer months.
The number of unhealthy ozone days has been on the decline in recent decades. The most recent monitoring period of 2016 to 2018 still experienced an excess over the federal target, but only slightly.1 It was the closest Hartford has ever been to meeting daily ozone targets.
Hartford challenges with ozone pollution are in sharp contrast to the city’s success in managing fine particulate pollution, or PM2.5. Hartford has met attainment levels for annual PM2.5 levels since 2004, and 24-hour PM2.5 levels since 2005. Since 2014, the city has not experienced any unhealthy days for PM2.5 pollution. Moreover, in the most recent monitoring period of 2016 to 2018, Hartford tied for cleanest metropolitan area in the country for 24-hour particle pollution.
Live air quality index data for Hartford, Connecticut is displayed at the top of this page. Due to the dynamic and fast-changing nature of air quality, it is always best to rely on real-time AQI ratings in Hartford.
While the Hartford-East Hartford region is tied for cleanest metropolitan area in the country for 24-hour particle pollution, the region ranks 25th for worst ozone pollution out of 228 surveyed metropolitan areas. Hartford ozone rankings places the city to a comparable status to Milwaukee (ranked 24th), and Philadelphia (ranked 23rd) for worst ozone pollution.
Hartford County has long been challenged by ozone pollution. While the 2016 to 2018 monitoring period represents the lowest ozone levels since monitoring began, Hartford still exceeds national standards and was rated an “F” for ozone pollution by the American Lung Association.
Ozone is a colorless and odorless air pollutant. As it concentrates with other pollutants, namely particulate matter, we tend to refer to it by another name — smog. Unlike most pollutants commonly measured and regulated by the Environmental Protection Agency (EPA), ozone is not emitted directly into the air by human activity. Rather, ozone is formed when sunlight, or UV radiation, and heat create a reaction from precursor pollutants in the air, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs). Due to this property, ozone is currently one of the least well-controlled pollutants in the United States.
Heightened ozone levels in Hartford County can aggravate respiratory problems in the nearly 830,000 residents defined as sensitive to pollution, including children, the elderly, and those with preexisting heart and lung disease.
Breathing unhealthy levels of ozone has been linked to short-term effects such as coughing, wheezing, chest tightness, asthma attacks, and increased risk of respiratory infection as well as long-term health effects including cardiovascular harm, reproductive harm, harm to the central nervous system, and early death.
Unhealthy ozone days are categorized into “orange” and “red” days. Orange days describe conditions when the AQI is between 101 and 150, temperatures are in the 80s and 90s, and winds are light. Red days describe conditions when AQI is between 151 and 200 on days that are hot, hazy and humid, the air is stagnant with little chance of precipitation.
In 2018, Hartford County experienced 17 orange days and one red day.2 Other nearby counties, such as Fairfield County in Ohio, Middlesex County in New Jersey, and New London County and New Haven County in Connecticut, all experienced even more frequent and severe unhealthy ozone days. Overall, Connecticut air quality ranks 10th in the US for worst ozone pollution.
The majority of air pollution in Hartford comes from outside of the city. Former Gov. Dannel P. Malloy (2011–2019) described Connecticut as the “tailpipe of the nation” for the significant amount of transboundary pollution the state experiences.3 Air pollution flows into Connecticut from neighboring states to the west and south, including Ohio, Pennsylvania, New York, and New Jersey.
Gas and coal-powered plants in the Midwest and industrial activity in states to the south, may contribute as much as 90% of the air pollution in Connecticut according to the director of the Planning and Standards Division in the Bureau of Air Management.4
In an effort to regain control over Connecticut's air quality, the State requested that the US EPA enforce more stringent air pollution standards in 9 surrounding states with power plants harming Connecticut air quality, and later sued the EPA to compel enforcement.
The Bureau of Air Management has also teamed up with NASA to better understand the origin and flow of emissions across the New England area with the hopes that additional understanding will provide a better outline for necessary regulations.5
Local emission sources in Hartford include vehicular emissions, local industry, and wood burning stoves, which are popular in the New England area, particularly during cold winter months.
Hartford has received a failing grade for ozone pollution, according to the American Lung Association, and experiences some of the worst ozone air pollution in the eastern US.
While Hartford’s air quality faces challenges in meeting safe ozone levels, the city fares well for PM2.5 pollution. Its annual PM2.5 average of 7.7 µg/m³ is safely within the US AQI index rating of “Good” and additionally meets the more stringent World Health Organization’s annual target of 10 µg/m³.
Hartford’s air quality additionally meets federal attainment levels for all other measured criteria pollutants, including PM10, NO2, SO2 and CO.
A study conducted by New York University estimates that 168 deaths and 472 hospital visits every year are related to unhealthy air pollution levels in Connecticut. The study found, moreover, that more people die in Connecticut each year from air pollution than in any other state in New England. The majority of this burden is thought to be attributed to the state’s ozone levels rather than concentrations of other pollutants.
There are a number of programs aimed at addressing Hartford air pollution and air pollution in the state of Connecticut. The most significant of these are the 1990 Clean Air Act Amendments and Connecticut Air Toxics Control Regulation.6
The 1990 Clean Air Act Amendments identified 174 common emission sources, including a wide range of facilities from power plants to dry cleaners and furniture manufacturers. The Environmental Protection Agency (EPA) developed unique standards for each of these sources. The Act additionally established a national permits program and enforcement program to help ensure compliance. A peer-reviewed EPA study found that the success of the 1990 amendments have resulted in large health benefits for people across the country, preventing an estimated 237,000 deaths up to 2020.7
The Connecticut Air Toxics Control Regulation dates back to 1986, and was deemed the most comprehensive pollution regulation for the time. The legislation set occupational standards for 30-minute and eight-hour emission limits, and compliance is maintained through engineering calculations, testing, and inspections conducted by the Connecticut’s Department of Energy and Environmental Protection (DEEP).
In order to better understand transboundary air pollution originating from outside of the state and local emission sources, Connecticut works with NASA’s Air Quality Applied Sciences Team (AQAST) to use satellite data to monitor the flow of fine particulates and nitrogen dioxide across the state.
+ Article Resources
 American Lung Association. (2020). State of the air – 2020.
 Shay J. (2019, April 24). Connecticut ozone pollution among worst in U.S.
 Hladky G. (2019, April 24). Connecticut’s air pollution is among the worst in the eastern U.S., according to new report.
 Hladky G. (2016, August 10). New study: Air pollution killing 168 in Connecticut each year.
 NASA. (2020). Connecticut: Tracking air pollution.
 Connecticut Department of Energy and Environment Protection (DEEP). (2020). Connecticut's management of toxic air pollutants.
 United States Environmental Protection Agency (EPA). (2020). Benefits and costs of the Clean Air Act 1990-2020, the second prospective study.