Companies and organisations have suspended services or activities because of the haze, and made changes to help workers.
Fast-food restaurants like McDonald's and KFC, for instance, stopped their delivery services as of last night.
In a Facebook post yesterday night, McDonald's said that it will be halting delivery orders until further notice to ensure the safety of its riders. KFC also said that it will resume delivery services "as soon as condition permits".
Mr Max Loh, Asean and Singapore managing partner of professional services firm EY, said the firm has an ongoing flexible working programme where staff can request to work from home on an ad-hoc basis as agreed with their team leaders. "Given the current haze situation, staff can leverage this programme if they wish to minimise commuting to and from work," he said.
Professional services firm PricewaterhouseCoopers Singapore said that it had given staff N95 masks and stopped outdoor activities, and was ready to put additional measures in place.
The Singapore Sports Hub also suspended all strenuous activities at its outdoor venues due to the deterioration of air quality yesterday. Outdoor venues affected include the OCBC Aquatic Centre and Water Sports Centre, said the Sports Hub.
It will "continue to monitor and assess the haze situation hourly". Outdoor venues will reopen and activities will resume when the air quality improves, it added.
The haze is also taking a toll on people here.
Dr Koh Hau Tek, medical director of Parkway Shenton, said its clinics are already seeing a 15 per cent increase in the number of patients with haze-related symptoms in the last two weeks after the haze started. "In the last two days alone, we are seeing a further 5 per cent increase in such cases," he said.
"If the PSI readings remain high over the next few days, we would expect to see even more cases as the typical presentation occurs only several days after prolonged exposure to severe haze."
And Dr Yik Keng Yeong from Tan and Yik Clinic and Surgery in Bishan said he has seen about 20 per cent more patients in the last two weeks with haze-related health issues, including bronchitis, respiratory tract infection and dermatitis.
A Ministry of Health (MOH) spokesman said hospitals were asked to ensure ample circulation of clean air indoors. For naturally ventilated wards, measures including closing windows and using portable air coolers have been implemented.
Since Sept 16, MOH has also activated the haze subsidy scheme, which subsidises treatment for haze-related conditions at participating general practitioners and polyclinics.
Lim Yi Han, Joanna Seow and Kok Xing Hui