An air quality advisory has been issued for Vanderhoof and Prince George due to high concentrations of fine particulate matter.
The advisory is expected to continue through Thursday.
People with chronic underlying medical conditions should avoid strenuous exercise until the advisory is lifted.
Staying indoors and in air conditioned spaces will help reduce fine particulate exposure.
Exposure is particularly a concern for infants, the elderly and those who have diabetes, and lung or heart disease.