Here is the health advisory from Haze.gov.sg
"The health impact of haze is dependent on one’s health status, the PSI level, and the length and intensity of outdoor activity. Reducing outdoor activities and physical exertion can help limit the ill effects from haze exposure. Given the air quality forecast for the next 24 hours, healthy persons should avoid prolonged or strenuous outdoor physical exertion. The elderly, pregnant women and children should minimise outdoor activity, while those with chronic lung or heart disease should avoid outdoor activity. Persons who are not feeling well, especially the elderly and children, and those with chronic heart or lung conditions, should seek medical attention."
In addition, if you have asthma or sensitive airways, please use your salbutamol inhaler if you are feeling short of breath. If that doesn't relieve the symptoms, please seek medical attention.