It’s been a hot summer in Boston, with air-quality alerts issued as the temperature and humidity levels climb. Poor air quality can pose dangers for those who have asthma and other lung diseases.

Hot, humid air traps ozone and particulate matter, which can irritate the lining of lung airways, triggering wheezing and breathing difficulties in asthma patients, according to Dr. Elliot Israel, director of the respiratory therapy department at Brigham and Women’s Hospital.

But it’s tough to tell a 9-year-old with asthma that he can’t play capture the flag or soccer at an outdoor summer camp for days on end.

On “yellow” air-quality days — which means the air quality is acceptable for most but may pose some problems for those with lung conditions — kids with asthma can probably continue their normal activities but should keep their inhaler on hand just in case they need to use it more. But if it’s a hazardous air-quality day — an orange or red on the government’s air-quality index found online on airnow.gov — they should head for sitting activities in the shade and stick to indoor exercise in an air-conditioned facility, Israel recommended.