The 3-hour PSI reading went up to 153 at 10pm. The PSI reading was 142 at 9pm.
A PSI reading of 101 to 200 means air quality is in the "unhealthy" range and 201 to 300 means "very unhealthy".
Anything above that means "hazardous".
Based on the 24-hour PSI readings, the Ministry of Health (MOH) advises that Singaporeans limit prolonged or heavy outdoor activities.
In particular, children, the elderly, and those with heart or lung diseases, should avoid outdoor activities and seek medical treatment early if they feel unwell.
MOH has activated the hospitals to prepare for the anticipated increase in the number of cases of asthma, bronchitis and conjunctivitis.
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