BOULDER, Colo. -- Residents along the Front Range woke up to hazy skies and the smell of smoke lingering in the air.

State health officials issued an air quality alert for the Front Range that remains in effect until at least 4 p.m. Wednesday. Smoke from the Fourmile Canyon Fire in west Boulder County is fueling air particulate pollution from El Paso County to Weld County, health officials said.

A Wildfire Smoke Health Advisory was issued for Boulder County as health officials urged people with health conditions -- heart disease, respiratory illnesses -- the very young, and the elderly to stay indoors when moderate to heavy smoke is present. That advisory also remains in effect until 4 p.m. Tuesday.

The Boulder Valley School District canceled recess for all schools in the district on Tuesday.

Read more: Fourmile Fire: Boulder air quality still poor, schools cancel outdoor recess - Boulder Daily Camera http://www.dailycamera.com/ci_16009224?source=rss#ixzz0yrrSjGrY DailyCamera.com

The heaviest smoke is expected to affect Boulder, Larimer, and Weld counties on Tuesday. Light-to-moderate smoke may reduce visibility in many areas of the Front Range as the fire generates a layer of haze, health officials warned.

"The fire is by far the overriding factor" in the air-pollution alert, state health spokesman Christopher Dann said.

"People need to pay particular attention to what the smoke is like in their neighborhood," he said. He cautioned people that smoke is unhealthy when visibility is less than 5 miles.

"When visibility gets down less than 5 miles that's when the health impacts become a real factor," Dann said.

"If smoke is thick or becomes thick in your neighborhood, you may want to remain indoors," the Colorado Department of Health and Environment warned in the Action Day Alert on its website. "Consider limiting outdoor activity when moderate to heavy smoke is present. Consider relocating temporarily if smoke is present indoors and is making you ill."