The hot and sunny weather across the province may be a welcome change, but officials warn the air quality in many urban areas of B.C. is becoming harmful to your health.

The official air quality risk was rated moderate for many B.C. communities Wednesday.

The worst readings came from the Fraser Valley, Prince George, the Central Okanagan and Metro Vancouver.

Air quality in the eastern parts of the Lower Fraser Valley is forecast to be fair to poor because of higher-than-average concentrations of ground-level ozone generated by the warm temperatures.

This air pollution is caused by car exhaust and other pollution trapped by the hot, dry air.

The advisory means anyone with breathing or heart problems should consider reducing physical exertion outdoors, officials said.

Air quality is expected to improve closer to the weekend.