The air quality has worsened slightly in Singapore and parts of Malaysia.
In Singapore, the three-hour Pollutant Standards Index (PSI) hit 79 at 12pm yesterday, up from 64 at 6am. As of 7pm, it was 67.
The 24-hour PSI reading - which the Government has said is a better indicator of whether people should worry about their health - also rose yesterday. At 7pm, it was 66-72 for the whole of Singapore, up from 58-62 at 12am.
A reading from 51 to 100 is in the moderate range, while a reading of 101 to 200 is considered unhealthy.
In Malaysia, the country's Natural Resources and Environment Minister, G. Palanivel, said that places like the Klang Valley and Nilai had moderate air quality, due to small fires at local levels amid the hot and dry weather.
As of 11am yesterday, the Air Pollution Index for 15 areas recorded good air quality while another 31 areas had moderate air quality, he said in a statement.
"None of the areas recorded unhealthy air quality," he said.
The Malaysian Meteorological Department said the hazy conditions in Malaysia might worsen in the next two months, if the dry season continues.
Recent observations also showed that Malaysia might encounter moderate transboundary haze if the heatwave continues.
Transboundary haze is the movement of haze from one country to another, explained Hisham Mohd Anip, a senior meteorologist from the department's National Weather Centre.
He said there might be an increase in haze in Malaysia and neighbouring countries, even as far as north Australia, if the dry season progresses.