(HealthDay News) – Two western U.S. states issued air quality alerts over the weekend as heavy smoke from fires blazing in Canada drifted south.

Both Colorado and Montana experienced air quality issues because of dozens of Canadian fires. A third state, Utah, noted that it was beginning to see smoke, while Idaho had experienced haze last week, the Associated Press reported.

“People with heart or lung disease, older adults and children should avoid prolonged or heavy exertion; everyone else should reduce prolonged or heavy exertion,” Colorado’s Department of Public Health and Environment said in its alert.

It issued air quality alerts and advisories for the eastern part of the state, including Denver.

Air quality is considered unhealthy for sensitive groups when particle pollution is between 151 and 200. Parts of Colorado’s Front Range were at 168 on Saturday, the AP reported.

In the province of Alberta, Canada, fires have led to the evacuation of thousands of residents. The health impact was “very high risk” on Saturday in the cities of Calgary and Edmonton, the AP reported.

The smoke in Montana was mostly in the central and eastern parts of the state.

In its alert, the Montana Department of Environmental Quality advised residents to avoid outdoor exertion if they could see haze or smoke.

More information

The American Lung Association has more on the impact of wildfires on lung health.

SOURCE: Associated Press

Source: HealthDay