So far in 2015, Connecticut had nearly triple the number of unhealthy ozone days compared to the previous year.
In 2014, the state experienced eight days in which the 8-hour average ozone level exceeded the national standard of 75 parts per billion. This year, so far, there have been 22.
That’s a 175 percent increase.
The number of unhealthy days may vary from year to year due to weather conditions, said the US Environmental Protection Agency. The agency recently announced it was tightening the 75 ppb standard to 70.
Connecticut saw spikes in the number of days when ozone monitors in New England recorded concentrations above levels considered healthy in 2010, 2012, and 2015. Those were the same years the state experienced the warmest average daily temperatures in the summer, according to data from the National Weather Service.
Over the long-term, New England has decreased the number of unhealthy ozone days over the decades.
In 1983, New England had 113 unhealthy days, compared with 24 this year. This downward trend is due to a reduction in the emissions that form ozone, according to the U.S. Environmental Protection Agency.