Prime Minister Lee Hsien Loong warned that the haze could last for weeks as air pollution indexes spiked to record levels, The Straits Times reported Thursday.
The haze is caused by forest fires in Indonesia's Sumatra Island, officials said.
At 1 p.m., local time, Singapore's pollution standards index reached 371. A PSI reading above 200 is considered "very unhealthy" while a PSI measuring above 300 is "hazardous."
At a news conference, Lee said the Health Ministry will begin a special program where people suffering from respiratory problems or conjunctivitis because of the haze can see their physician, pay $10, and the ministry will settle the rest of the bill. The program applies to Singaporeans less than 19 years of age or more than 64, Community Health Assist Scheme card holders and PA (public assistance) and Medical Fee Exemption Card holders.
The haze, Lee said, could "easily last for several weeks and quite possibly longer until the dry season ends in Sumatra."
The air quality has led to accusations between Singapore and Indonesia over who's responsible for the smog, the BBC reported.
Environment officials from the two nations held an emergency meeting in Jakarta Thursday.
Vivian Balakrishnan, Singapore's minister for Environment and Water Resources, posted on his Facebook page he will demand "definitive action" from Indonesia.
"No country or corporation has the right to pollute the air at the expense of Singaporeans' health and well-being," he said.
Indonesian Minister for People's Welfare Agung Laksono said Singapore was "behaving like a child."
"This is not what the Indonesian nation wants, it is because of nature," he said.
Parts of Malaysia have also recorded "hazardous" pollution levels, the BBC said. More than 200 schools in the country's south were ordered closed and the Malaysia's Environment Department, which also banned open burning in some states.