Smoke from hundreds of wildfires in Canada is lingering over the northern U.S., spreading across to roughly a dozen states from Wisconsin to Maine.

The smoky air poses potential health risks for people including children, older adults and those with heart or lung disease.

Air quality alerts were issued across the Northeast and Midwest US on August 5 due to elevated PM2.5 levels from Canadian wildfire smoke. Affected states include New Jersey, New York, Connecticut, Pennsylvania,