Metro Vancouver has lifted an air quality advisory for  eastern areas of Metro Vancouver and the Fraser Valley because cooler temperatures have reduced the level of air pollution.

Despite the lifting of the district's advisory, the provincial government's Air Quality Health Index is still forecasting pollution levels across the region will range between four and five on a scale of one to ten on Wednesday.

The worst air pollution in the province is in Quesnel, Prince George and Williams Lake, where the Air Quality Index hit six, seven and eight on Wednesday morning

After a week of record breaking heat, temperatures are expected to cool across B.C. over the coming days, with rain in the forecast for the weekend.

Nevertheless several significant wildfires continue to burn across parts of B.C.

Ground-level ozone concerns

Metro Vancouver's advisory was first issued on Sunday by the the regional district because of high concentrations of ground-level ozone.

Ground-level ozone is formed from several factors including nitrogen from vehicles and other fossil fuel consumption, volatile organic compounds from sources such as paint, and hot weather and sunlight.

While ozone in the earth's upper atmosphere helps block harmful ultraviolet rays from the sun, at ground level it can cause health problems for humans.

Exposure is particularly a concern for infants, the elderly and those who have underlying medical conditions such as lung or heart disease and asthma.