Air quality concerns persist Thursday in Massachusetts due to the wildfire smoke continuing to stream in from Canada, and health officials are urging people to take precautions.

Canadian wildfire smoke map

Statewide air quality alerts, issued by the Massachusetts Department of Environmental Protection, are in effect through midnight.

The air is considered unhealthy for sensitive children and adults, including those with asthma, lung or heart disease, and older adults. Sensitive groups should limit prolonged outdoor activity, or heavy outdoor exertion.

AQI Boston

The Air Quality Index in Boston is expected to be 140 today.

Why is the sky yellow?

Experts say what we’re seeing is part of a growing pattern fueled by bigger and longer wildfire seasons.

Click here for more on the science behind our wildfire smoke-darked skies.

It’s the second day that Boston’s been blanketed by hazy skies from Canadian wildfires. Here’s everything to know about where it’s coming from, how air quality is affecting it and the science behind it.

Smoke in Boston… when will haze clear?

There was a clearing Wednesday night which helped for those enjoying the fireworks in Boston for the tall ships, and the Little League championship game between Boxford and Beverly.

“So we were monitoring it, and I was kind of seeing if they’re going to cancel the game. But we live near the ocean, a lot of wind, and it seemed to have cleared up. And I’m comfortable having my son play tonight without any concerns,” Bob McGraff said.

Meteorologists says unfortunately the air quality is expected to get worse as the day goes on.

Tomorrow sees a temporary improvement, but we’ll continue tracking the smoke as long as the fires continue to burn.

Since they’re not expected to be extinguished for a long time, smoke is likely to be in our forecast (at varying degrees) for weeks to come.

Doctors say these conditions are especially harmful to vulnerable groups.

People with lung disease are at greater risk from exposure to ozone, while people with either lung disease or heart disease are at greater risk from exposure to particle pollution.

Sensitive groups should take more breaks and do less intense activities, and follow asthma action plans and keep quick relief medicine handy.

Pay attention to your body. If you notice symptoms like tightness in your chest, wheezing or coughing, staying indoors with filtered AC is the best remedy.

Otherwise, wearing an N-95 mask and staying hydrated are key.