More than a million advised to stay inside in three states

More than a million Americans are advised to limit their time outdoors due to unhealthy air quality levels.

“Unhealthy” levels of air quality are detected in parts of Indiana , Michigan and Illinois as of 6 a.m. ET on Monday, marked in red on the Environmental Protection Agency’s AirNow map.

In areas with unhealthy air quality, residents are advised to limit prolonged or strenuous outdoor activities and take breaks when needed.

Why It Matters

High levels of particle pollution can cause a range of health problems, ranging from coughing and wheezing up to asthma attacks, heart attacks, strokes. It is also linked to early death for people with heart or lung disease, according to AirNow.

The risks are highest for sensitive groups such as young children, elderly people, those with ex