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Explainer: Montana’s air quality ratings

Posted at 4:12 PM, Aug 16, 2018
and last updated 2018-08-16 18:12:18-04

Smoke continues streaming into Montana from wildfires burning in the western United States, causing hazy skies and increased health risks.

The Montana Department of Environmental Quality (DEQ) provides daily updates about wildfire smoke and air quality. While decreasing air quality often leads to hazy conditions, it can also present health risks.

The DEQ rates air quality based on the amount of particulate matter (PM) in the air, which is often caused by smoke from wildfires.

In addition to being emitted from wildfires, PM can also come directly from other sources, such as construction sites, unpaved roads, fields, and smokestacks. The EPA says that PM is a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.

The air quality ratings in Montana are assigned a color code. The color green, for example, means that there are no negative health effects, and no precautions are necessary for outdoor activity.

“Moderate” (yellow) means that there is the possibility of aggravation of heart or lung disease for people with cardiopulmonary disease, and the elderly.

Here are the other ratings, listed in order of increasing danger or health risks:

  • Unhealthy for Sensitive Groups (orange): Increasing likelihood of respiratory symptoms in sensitive individuals, aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly. People with respiratory or heart disease, the elderly and children should limit prolonged exertion.
  • Unhealthy (red): Increased aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; increased respiratory effects in the general population. People with respiratory or heart disease, the elderly, and children should avoid prolonged exertion; everyone else should
  • limit prolonged exertion.
    Very Unhealthy (Purple): Significant aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; significant risk of respiratory effects in the general population. People with respiratory or heart disease, the elderly, and children should avoid any outdoor activity; everyone else should avoid prolonged exertion.
  • Hazardous (maroon): Serious aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; serious risk of respiratory effects in the general population. Everyone should avoid any outdoor exertion; people with respiratory or heart disease, the elderly, and children should remain indoors.

The DEQ publishes a daily Wildfire Smoke Update, you can find it here.

Reporting by David Sherman for MTN News