A wildfire haze filled Colorado skies Monday, July 22, from fires that continue to burn across the West.

The wildfire smoke muddled what was otherwise a bluebird morning in places like Summit County. In Breckenridge, one air quality monitoring station ranked conditions as “unhealthy for sensitive groups,” while stations located throughout most of the rest of the state indicated “moderate” air quality conditions, according to the federal government’s fire and smoke map.

“We do expect this smoke, this haze, this poor air quality to continue for the majority of the workweek,” National Weather Service forecaster Russell Danielson said Monday morning.

The wildfire smoke visible Monday wafted into Colorado from the north where wildfires are burning in Canada, Danielson said. As a high pressure system shifts eastward, he said wildfire smoke from blazes burning in Washington, Oregon and California will be drawn into the Colorado Rocky Mountains later in the week.

On Monday, the Colorado Department of Health and Environment issued an ozone alert warning that ozone concentrations in the “unhealthy for sensitive groups” category are possible throughout the northern Front Range region, including Denver, Boulder, Fort Collins and surrounding areas.

The highest concentrations of smoke Monday morning appeared at higher elevation locales in north-central Colorado, including the Park Range and northern parts of the Front Range, according to the state’s smoke blog.

Wildfire smoke — which is a mix of gasses and particles from burning trees, plants, buildings and other materials — can impact human health, irritating people’s eyes, nose and throat, causing wheezing, coughing and difficulty breathing, especially for those with asthma, bronchitis or other lung diseases, according to the Colorado Department of Health and Environment. Unusually sensitive people should reportedly consider reducing prolonged or heavy outdoor exertion due to air quality impacts.

The National Wildfire Preparedness Level is now at 5, the highest level, which indicates a “full commitment of national resources” and a high potential for significant wildland fires to emerge, according to the National Interagency Fire Center. Nearly 22,000 wildland firefighters are assigned to wildfires nationwide as 66 large, active wildfires burning nationwide have scorched more than 1 million acres, an area larger than the entirety of Yosemite National Park, the national fire center reports.

In Colorado, at least seven wildfires continue to burn on over 2,000 acres, according to the National Interagency Fire Center. The largest of those is the Oak Ridge Fire in the Sangre De Cristo Mountains, which on Monday had burned an estimated 1,300 acres, cost an estimated $18 million and was about 90% contained.

Climate change, driven by the burning of fossil fuels, has increased the risk and extent of wildfires in the western U.S. over the last two decades, according to the National Oceanic and Atmospheric Administration. Research shows that human-caused changes in climate are creating warmer, drier conditions that lead to longer and more active fire seasons.

Danielson said that as the week wears on, Coloradans are unlikely to see much reprieve from wildfire smoke.

“There are small chances each day of showers and storms but we’re not expecting them to really be enough to reduce the poor air quality, unfortunately,” Danielson said. “Maybe by the weekend we’ll see more of a chance of storms and perhaps an improvement in smoke. But the smoke forecast often is tough to do beyond a couple days.”