State officials issued an air quality advisory Monday for the Portland-Vancouver metro area as temperatures skyrocketed for another day in the region.

The Oregon Department of Environmental Quality said ozone pollution from the heat could reach a level unhealthy for sensitive groups through Tuesday evening. Pollution levels peak in the late afternoon and early evening.

Health officials recommend sensitive groups limit outdoor activity when pollution levels are high. Those at greatest risk of harm from breathing air containing ozone include elderly people, children and people with asthma and lung disease.

The general public can help limit smog pollution by taking public transit, not using lawn mowers and other gas-powered machinery, limiting paint projects and avoiding idling their cars.

Smog forms when high temperatures and low wind combine with pollution from cars, gas-powered engines and chemicals in paints and aerosols. The pollution reacts with sunlight and heat to produce haze.

You can monitor ozone, fine particle pollution and nitrogen dioxide pollution in Oregon on an interactive map.