Air quality advisory issued for parts of Lower Mainland, Fraser Valley

The hot, sunny weather has resulted in an air quality advisory from Metro Vancouver for eastern parts of the region and the Fraser Valley.

High concentrations of ground-level ozone areexpected to persist until at least Mondayor longer if hot, sunny weather continues, Metro Vancouver said in a statement.

Ground-level ozone is formed when pollutants emitted from burning fuel mix withvolatile organic compounds and react in the air in the presence of sunlight.

The highest levels of ground-level ozone are generally observed between mid-afternoon and early evening on summer days.

WATCH: Metro Vancouver explains ground-level ozone.

The advisory comes at the same time as a special weather statement for Metro Vancouver and the Fraser Valley about a brief hot spell for these areas.

Environment Canada says aridge of high pressure has been building over southern B.C. this weekend with temperatures peaking today and then gradually declining as the week progresses.

Abbotsford in the Fraser Valley hit almost 35C on Sunday, according to the agency.

Metro Vancouver is asking people in the eastern area of the region and in the Fraser Valley to avoid strenuous outdoor activities from mid-afternoon to early evening.

It says people with underlying conditions such as lung or heart disease are more at risk from poorer air quality.

Metro Vancouver is a federation of 21 municipalities, one Electoral Area and one Treaty First Nation that collaboratively plans for and delivers regional services such asdrinking water, wastewater treatment and solid waste management.

It also regulates air quality.