Thick haze from land-clearance fires in Indonesia has continued to shroud parts of Malaysia.
Visibility in the capital, Kuala Lumpur, remained poor on Monday as officials ordered schools closed in Kuala Lumpur and Selangor state.
In Singapore air quality continued to improve after last week's record haze, as wind conditions changed.
Indonesia is working to control the blazes but so far cloud-seeding has not produced enough rain, an official says.
Sutopo Purwo Nugroho, a spokesman for Indonesia's national disaster agency, said they had "carried out 14 water-bombings, dropping a total of 7,000 litres (1,820 gallons) of water onto the fires".
He added that altogether, four helicopters had been deployed for water-bombing operations while two planes were conducting cloud-seeding, AFP news agency reported.
However, Indonesian disaster agency official Agus Wibowo told AFP that two cloud-seeding attempts tried in Riau province over the weekend were not successful.
"The cloud-seeding technology is meant to speed up rainfall, but with few clouds, there's little we can do. The rain was more like a drizzle."
On Sunday Malaysia declared a state of emergency in two southern districts as air pollution levels reached a 16-year high, leaving two towns in virtual shutdown.
Conditions eased somewhat in the south on Monday but worsened in other parts of the country.
The Air Pollutant Index (API) in Kuala Lumpur was near the 200 level, or "very unhealthy", on Monday, while in Port Dickson, located across from Sumatra, it reached 335, or "hazardous".
The smog is being blamed on illegal land-clearing fires burning in Indonesia's Sumatra island, mainly in Riau province.
Malaysia's environment minister is scheduled to meet his Indonesian counterpart on Wednesday to discuss the situation.
Malaysian and Singaporean officials are also seeking to move forward a meeting of the Association of South-East Asian Nations (Asean) haze committee to next week instead of in August, reports say.
Singapore's prime minister has warned that the problem could continue for weeks, as teams struggle to bring the fires under control amid dry weather.
Meanwhile air quality in Singapore improved over the weekend "due to a change in the direction of the low-level winds", the National Environmental Ministry (NEA) said in an advisory.
"The prevailing wind conditions are expected to persist for the next few days," NEA said.
However, Singaporean Prime Minister Lee Hsieng Loong said on his Facebook page that Singaporeans "must expect the haze to come back".
Singapore's Pollutant Standards Index hit a record high of 401 on Friday - the previous high was 226 in 1997 - before slowly dropping over the weekend. On Monday, readings remained below 100.