Air quality around Billings steadily deteriorated on Monday as smoke from wildfires on the west side of the state began moving east.
By 3 p.m. Monday, the state Dept. of Environmental Quality had classified the air around Billings as unhealthy for people with sensitive lungs, bumping it from moderate, where it had been classified most of the morning.
By 4 p.m. the level was raised again, and the air was classified unhealthy for all populations. The air quality scale has six categories, ranging from "good" to "hazardous," with the two unhealthy categories in between.
"You can't really control it," said Clark Snyder, a coordinator for environmental health at the Yellowstone County health department. So, it's important for county residents to limit their exposure, he said.
Those most at risk are people who have asthma, those who have heart and lung disease, children whose lungs are still growing, senior citizens and pregnant women.
Wildfire smoke is dangerous because it's filled with microscopic particles — ash, debris and even liquids — that irritate the sensitive tissue in the lungs. For those who deal with asthma, chronic obstructive pulmonary disease or other lung issues, wildfire smoke in the air can be particularly dangerous.
"Environmental smoke will cause inflammation in the lungs," said Robert Merchant, a critical care and pulmonary disease doctor at Billings Clinic.
Merchant had three patients in the hospital Monday with breathing issues because of the poor air quality in Billings.
Both Merchant and Snyder are telling those with sensitive lungs to stay indoors, keep the windows shut and run the air conditioner.
"Be much more attentive to your symptoms," Merchant said.
If breathing becomes difficult or if other symptoms show up, Merchant recommends folks increase their medications or call their doctor.
Merchant and Snyder cautioned against exercise and strenuous activities outdoors while air quality remains poor. Physical exertion causes the lungs to draw in air more deeply and absorb extra oxygen. That leaves them particularly sensitive to the particulate matter in the air.
The best thing people can do is "avoid prolonged exposure," Snyder said.