Due to smoke from Canadian wildfires, the Massachusetts Department of Environmental Protection (MassDEP) has issued an air quality alert effective until at least 11:59 p.m. tonight in five counties in western and central Massachusetts.

Smoke is expected to impact air quality in Berkshire, Franklin, Hampshire, Hampden and Worcester counties.

The anticipated air quality may be unhealthy for sensitive groups. Sensitive groups include people with heart or lung disease, such as asthma, older adults, children, teenagers and people who are active outdoors. People with either lung disease or heart disease are at greater risk from exposure to air pollution.

MassDEP advises people in sensitive groups to reduce prolonged or heavy outdoor exertion, take more breaks, do less intense activities, follow asthma action plans and keep quick relief medicine handy.

More details, including forecasts and real-time data, can be found at MassDEP’s MassAir Online site.