EAST PROVIDENCE, R.I. (WPRI) — New England saw a slight increase in days with unhealthy air quality over the summer, according to new information released by the U.S. Environmental Protection Agency (EPA).

The EPA’s New England office said the uptick was based on data collected between March and September 2022.

In total, there were 24 days when ozone concentrations reached unhealthy levels across New England last year, compared to 23 days in 2021.

“Thanks to the hard work and dedication of federal and state efforts, we made great progress in reducing ozone pollution over the past several decades and providing cleaner air for our communities,” EPA New England Regional Administrator David Cash said.

Here’s a look at the number of unhealthy ozone days in each New England state:

  • Connecticut: 23 days (up from 21 in 2021)
  • Rhode Island: 5 days (5 in 2021)
  • Massachusetts: 4 days (4 in 2021)
  • Maine: 2 days (4 in 2021)
  • New Hampshire: 2 days (3 in 2021)
  • Vermont: 0 days (0 in 2021)

“Unfortunately, New England, and especially coastal Connecticut, continues to experience an unacceptable number of days with unhealthy air quality,” Cash added.

Cash said the EPA will keep working toward improving the air quality by taking steps like reducing pollution from vehicles and power plants.

What is ozone?

Ground-level ozone forms when organic compounds and oxides of nitrogen interact with the strong sun during the summer. Cars, trucks, and buses typically omit pollution that create ozone. The EPA says that gas stations, print shops, household products such as paints, cleaners, lawn and garden equipment contribute to ozone.

What makes an ‘unhealthy’ day of air pollution?

Any day that experiences ozone levels exceeding 0.070 parts per million (ppm). Many factors impact the number of days each year, especially weather conditions. Hot, sunny, and summer-like weather greatly helps ozone formation. For example, this past summer was hot and dry, with many local areas experiencing extreme drought conditions.

Since 1983, New England has experienced a decrease in the number of unhealthy ozone days, according to the EPA. In fact, in 1983, New England had 118 unhealthy days, compared to 24 in 2022.