PROVIDENCE, R.I. (AP) – The number of smog days in New England doubled this year compared with last year, an increase federal officials blamed on a streak of hot summer weather.

The Environmental Protection Agency on Monday reported that the number of unhealthy ozone days doubled to 26 this year from 13 last year.

Rhode Island had eight days of unhealthy air this summer, an increase from four in 2004.

The picture was worse in Connecticut and Massachusetts. Both those states had 20 days of unhealthy air this summer – up from six last year in Connecticut and eight last year in Massachusetts.

EPA officials attributed the increases to an unusual number of 90-degree days this summer. Sunlight and warm weather accelerate the production of ground-level ozone, more commonly called smog.

Exposure to high levels of ozone can make people more susceptible to respiratory infection and harm those with asthma and other breathing ailments.

Over the long term, ozone levels have declined in the region, the EPA said. For example, in 1983, New England had 90 unhealthy days, more than three times the number in 2005.