A road dust advisory has been issued for the Bulkley Valley and Lakes, including Smithers by the Ministry of Environment and Northern Health.
High concentrations of coarse particulate matter are expected to persist until there is precipitation or the streets are cleared of winter traction material.
Levels tend to be highest around busy roads and industrial operations.
This advisory is in effect until further notice.
People with chronic underlying medical conditions should postpone strenuous exercise near busy roads until the advisory is lifted.
Exposure is particularly a concern for infants, the elderly and those who have diabetes, and lung or heart disease.