As the haze enveloping Singapore hovers in the unhealthy range, schools are taking precaution by turning on air purifiers.
Teachers are to look out for students with pre-existing lung or heart conditions and ensure that they are moved to enclosed indoor spaces such as the school library, the Ministry of Education (MOE) said.
As national exams start - the Primary School Leaving Examination (PSLE) for listening comprehension takes place today - schools have made arrangements for all candidates to take their papers in enclosed spaces, such as classrooms or halls, the ministry told The Straits Times.
"Air purifiers will also be provided so that it is safe for the examinations to continue, should haze conditions unexpectedly worsen," it said. It explained that schools are guided to turn on the air purifiers when the air quality hits the "very unhealthy" range.
But they can assess the situation and choose to turn them on earlier when the one-hour PM2.5 readings are elevated.
There are four bands on the PM2.5 concentration scale: zero to 55 for normal, 56 to 150 for elevated, 151 to 250 for high, and very high for any higher readings.
The PM2.5 reading is a gauge for immediate activity, whereas the 24-hour Pollutant Standards Index (PSI) should be relied on when planning future activities.
The air quality is considered "very unhealthy" when the PSI ranges from 201 to 300.
A PSI reading of zero to 50 indicates good air quality, while a reading of 51 to 100 is in the moderate range, and a reading of 101 to 200 is considered unhealthy.
MOE said processes are in place to help students who are unwell during national examinations, including those affected by the haze.
If a student cannot sit the examination or continue with it, his health must take priority, it said.
"There are existing procedures for schools to escalate the situation to the Singapore Examinations and Assessment Board for special consideration so that the candidate will not be penalised."
Some parents told The Straits Times they hoped the PSLE would not be rescheduled as it would be disruptive, while others are not taking any chances and giving their children extra supplements and vitamins to help them stay well.
MOE said affected exam papers will be rescheduled and the exam period extended if school closures coincide with national examinations like the PSLE.
It had said it will consider closing schools when the air quality forecast for the next day is "hazardous" - when the 24-hour PSI rises above 300.
In 2015, when the PSI readings were near hazardous levels, schools were closed for a day.
Henry Park Primary School principal Martin Koh said Primary 6 pupils will be taking their exams in air-conditioned spaces like the school hall and classrooms.
"All classrooms are equipped with air purifiers and teachers are briefed on how they can support children who are affected by the haze," he said. "Internally, there is a team monitoring the PSI reading and will advise the student body when necessary."
He added that the school has cancelled an outdoor event - the Mid-Autumn Lantern Festival - for Primary 1 and 2 pupils that was to take place today.
Westwood Primary School principal Ng Yeow Ling said it is monitoring pupil and staff well-being, especially security guards and cleaners who work outdoors.
They are advised to take breaks, rest indoors and, if needed, use the masks that are provided.
Madam Alicia Lee, who has twin boys in Primary 6, said: "One of them has a sensitive nose. But I trust he can take care of himself."
Added the 41-year-old, who works in customer service: "They hope the PSLE will not be postponed due to haze as they want to get it over with as soon as possible."
Madam Joanne Chong, whose daughter is in Primary 6, said: "I told her to drink a lot of water, take probiotics, vitamins... her classmates have been down with cough and fever because of the haze."
The 40-year-old housewife added: "I really pity the kids, they have been studying very hard. It is like being ready to go to battle, and if the exam has to be rescheduled, it is a bit anti-climactic."