In Singapore, people managed to breathe a little easier yesterday afternoon, when thundery showers in the western part of the country brought respite from the haze.
As of 7pm, the 24-hour Pollutant Standards Index (PSI), a measure of air quality, had dropped to between 69 and 77, at the high end of the moderate range, which is from 51 to 100.
On Tuesday, it had entered the unhealthy range, which is from 101 to 200.
The improvement occurred even though the number of hot spots detected in Sumatra, Indonesia, jumped from 38 on Tuesday, to 140 yesterday.
Showers are forecast for late morning and early afternoon today, the National Environment Agency said yesterday.
But the haze is expected to persist today, as prevailing winds are forecast to continue blowing from the south or south-west, carrying smoke haze from Sumatra here, the agency said.
The 24-hour PSI is expected to be at the high end of the moderate range and low end of the unhealthy range.
The haze may deteriorate further if the winds are unfavourable.
The elderly, pregnant women and children are advised to minimise prolonged or strenuous outdoor activity, while those suffering from chronic lung or heart disease should avoid these activities when the 24-hour PSI exceeds 100.