The skies over Colorado have been hazy the last few weeks due to all the wildfires burning in the west. That's meant itchy eyes, stuffy noses and maybe even asthma attacks for some residents.
The state public health department issued 10 advisories as a result of the smoke, recommending Coloradans stay inside. And overall, about a fifth of the days this year, 43, have prompted such air pollution advisories. Something invisible -- ground-level ozone -- is responsible for the majority of those.
But that's not out of the ordinary. There have been 24 ozone-related advisory days so far this year, compared with 17 in 2014 and 32 in 2013.
"It's certainly reasonable to say that the number of pollutant-related advisories so far in 2015 falls well within the normal range," said Christopher Dann, a spokesman for the Colorado Department of Public Health and Environment who spoke with Colorado Matters host Ryan Warner.
The federal Environmental Protection Agency has proposed new stringent standards to lower ozone levels in Colorado, but business leaders claim they would harm the state's economy and Gov. John Hickenlooper isn't sold on the idea, according to CBS4 News.
Other than ozone and smoke, action days are issued for fine particulate matter in the air, carbon monoxide or other pollutants.
On those days, the air is considered potentially unhealthy for 24 hours. Some groups, like the elderly, people with asthma and other respiratory conditions, and children may be more vulnerable than others. Health officials advise actions such as fueling up vehicles after the sun goes down to lower than chances that vapors "cook" in the hot summer sun and become harmful ground-level ozone.