Washington, Jun 29 (IANS): Millions of Americans are on alert for unhealthy air quality as wildfire smoke from Canada continues to drift to the US.

The US National Weather Service (NWS) on late Wednesday issued air quality alerts for at least 20 states from Minnesota to as far south as Georgia, reports Xinhua news agency.

The unhealthy air quality alerts even extended to the Northeast including all of New York state and New Jersey.

"Unhealthy levels of smoke are expected for a wide swath of the Midwest. Smoke from wildfires in Canada is impacting the area," the NWS tweeted.

"If you have to be outside, take breaks indoors and consider using an N-95 mask to help reduce the smoke you breathe in," the NWS suggested.

Wildfire smoke from Canada is currently blanketing large swaths of the US.

Wildfire smoke and ash can irritate eyes, nose, throat and lungs, making people cough or wheeze and can make it hard to breathe, according to the Centers for Disease Control and Prevention (CDC).

The most effective way to protect from wildfire smoke is to stay indoors or limit time outdoors. This is especially important for those with heart or lung conditions who are at higher risk for adverse health effects, the CDC added.