New Hampshire's Department of Environmental Services is expecting air pollution concentrations to reach unhealthy levels in Portsmouth and other seacoast communities.
The outlook for Tuesday is for unhealthy concentrations of ground-level ozone, the main component of smog. The unhealthy air quality comes from the persistence of high temperatures under sunny skies, which can combine with local emissions.
The department is advising area residents to take precautions to protect their health by limiting prolonged outdoor exertion. Sensitive individuals include children and older adults; anyone with lung disease such as asthma, emphysema, and bronchitis; and people who are active outdoors.
The department says even healthy people may experience mild health effects Tuesday and should consider limiting strenuous or prolonged outdoor activities.
The air is expected to be cleaner on Wednesday, with lower temperatures and cloudier skies.