MESA COUNTY, Colo. (AP)- A health advisory is in effect for the Grand Valley.

Mesa County Health Officials say the high levels of smoke, or pollution, is mainly produced from wood burning, vehicle exhaust and other combustion sources.

Individuals who are sensitive to smoke, including those with heart disease, respiratory illnesses, young children and the elderly are being urged to limit outdoor exertion until smoke levels decrease.

The department is urging all residents to limit travel by carpooling and eliminating unnecessary trips.