State issues air quality warning for Willamette Valley and northern Umatilla County • Oregon Capital Chronicle

While residents are battling triple-digit temperatures, Eastern Oregon and the Willamette Valley are facing high levels of smog, partly caused by the heat.

The Department of Environmental Quality, Lane Regional Air Protection Agency and Southwest Clean Air Agency issued an air quality alert Monday due to elevated ozone levels. They said it will affect northern Umatilla County through Monday and continue in the Portland-Vancouver region and Willamette Valley through Tuesday — along with the heat wave.

On Monday afternoon, air quality was worst in Eugene, Silverton, south of Portland and Hermiston across the state.

Health officials said certain groups are particularly vulnerable to the health effects of smog, including children, pregnant women, older adults and people with heart or respiratory conditions. They recommended limiting outdoor activities when pollution levels are high.

They also said people should:

• Limit driving and use public transportation or carpooling instead.
• Avoid unnecessary engine idling.
• Refuel your vehicle in the cooler evening hours.
• Avoid using petrol-powered equipment in the garden.
• Postpone painting and spraying work.

Smog is created when high temperatures and light winds combine with air pollution from cars, gasoline engines and chemicals in paints and aerosol cans. They react with sunlight and heat to create ozone and haze.

Pollution increases throughout the day as the sun beats down, with levels highest in the afternoon and early evening, when it’s also hottest. This means that an air quality monitor that shows clean air in the morning can quickly reach unhealthy levels later in the day.