Metro Vancouver issued an air quality advisory on Wednesday for the eastern regions of the Lower Mainland.
The air quality advisory applies to Coquitlam, Port Coquitlam, Surrey, Langley, Maple Ridge, Pitt Meadows and the Fraser Valley Regional District.
The advisory is due to high levels of ground-level ozone, which is created when nitrogen oxides – pollutants emitted when fuels are burned – and volatile organic compounds react in the air.
Officials are advising people to avoid strenuous outdoor activities during mid-afternoon to early evenings, when ozone levels are at their highest.
Wildfire smoke in the interior is affecting visibility in the region, but it’s not harming air quality.
READ MORE: Scorching heat hits Lower Mainland
With a heat warning still in effect, people should remember to hydrate and spend time in cool, air-conditioned spaces.
Infants and the elderly and those with underlying medical conditions are at highest risk to experience negative symptoms such as chest discomfort, shortness of breath, coughing or wheezing.