Nur Shahidah Nazri, who is a certified assessor from the Department of Occupational Safety and Health (DOSH), said a Non-Dispersive Infrared (NDIR) CO2 monitor serves as a ventilation marker.
“NDIR CO2 monitors can indicate how well a space is ventilated. If the CO2 concentration is high, this means that the room has poor ventilation. This could pose a danger to everyone in the room as CO2 is a proxy to Covid-19,” said the Melchers Malaysia IAQ assessor.
Nur Shahidah warned the public to be wary when buying cheap CO2 detectors as fake monitors are widely sold online and that genuine NDIR monitors typically cost around RM250 and above.
She claimed that the guidelines given to schools for school reopening did not come from indoor air quality experts or DOSH.
“Removing curtains and carpets in classrooms is not the solution,” she said, adding that most schools in urban areas were air-conditioned, posing a greater risk of Covid-19 transmission if proper ventilation was not introduced.
“Air-conditioned classrooms use a split unit system which will only recirculate air without the introduction of any fresh air to dilute the contaminants in the classroom.
“If there was a Covid-19 infected student in the classroom, the air the student exhales (which contains the virus) would linger and possibly infect other students,” she said.
She said it was time for the government to follow the best practices of other countries to ensure a safer learning environment for students.
A normal range of CO2 levels in classrooms should be around 500 to 600 ppm which would be an indication of a well-ventilated space for students, she said.
One way to dilute the air system in classrooms was to open all windows 30 minutes before classes and 30 minutes after as this would help purge and flush the contaminated air.
“After all, keeping doors open continuously may introduce other contaminants such as particulate matter (PM) 2.5 into the classrooms.
“Schools can also install an exhaust fan or an industrial blower to improve air circulation further,” she said.
Nur Shahidah hoped schools would consider these suggestions as the virus will only continue to evolve and thus ventilation would play an essential role in the fight against Covid-19.
International Islamic University Malaysia’s (IIUM) Dr Maryam Zahaba said all schools should follow the set standards on IAQ by DOSH.
“There are mitigation measures by DOSH on how to reduce the risk of Covid-19 transmission. Schools may follow these guidelines to reduce indoor air contaminants such as through the installation of an exhaust fan or the use of air purifiers that can eliminate Covid-19,” she told FMT.
Like Nur Shahidah, Maryam agreed that using NDIR CO2 monitors was important to help measure the level of ventilation in a classroom, adding that the CO2 levels should also be below 800 ppm.
Maryam also noted that SOPs such as physical distancing, the use of hand sanitisers and the wearing of masks indoors must be continued in addition to the set standards by DOSH.