Ventilation audits in schools across New South Wales have come under fresh scrutiny after two reviews of the same Blue Mountains school weeks apart resulted in the student capacity of one classroom rising by 500%.
The government announced last year it would conduct ventilation audits at the 2,200 public schools across NSW to ensure there was enough fresh air inside classrooms, libraries and halls to prevent the spread of Covid-19.
But as schools return for 2022 amid high community transmission of the Omicron variant in the state, new questions are being asked about the audits. The Guardian obtained copies of two audits conducted for the same school, which came to dramatically different conclusions about student capacity.
In one example, a 55.4 sq metre “teaching space” was originally classified as having capacity for 25 students. But a second audit conducted less than three weeks later found that 154 students could safely occupy the room.
In another case, a slightly larger room went from a capacity of 26 students to 77. In a third, the school’s bay was changed from a capacity of six to 19. In another, the result went the other direction; a classroom designated as being safe for 77 students was downgraded to 39.
The department did not respond to questions about specific schools, but said they “worked with schools and provided guidance on how spaces should be used relative to the availability of natural ventilation”.
“In many cases, this resulted in updated information on reports which were reissued to schools.”
The Guardian understands the second audit was based on an in-person inspection of the school and the individual characteristics of the teaching spaces, while the first was an indicative measurement based on the room’s size in square metres.
But experts have questioned how the audits could have come to such dramatically different conclusions.
Lidia Morawska, director of the International Laboratory of Air Quality and Health at the Queensland University of Technology, said the audit for the school was based on calculations that resulted in classroom capacity below 1 sq metre per person.
“If the space per person is less than 1 sq metre people would be touching each other like sardines so at this close distance ventilation does not help much,” she said.
“It is a very big concern if people could be at such a close proximity to each other – then they are at a very high risk of inhaling high concentration of particles emitted, and if the particles contain the virus then getting infected.”
Morawska also questioned the widespread use of air conditioning in schools with windows that do not open. Dubbed “sealed schools”, there are 48 of them across the state.
The department has said that air conditioning has been installed in all “sealed schools”, and the Guardian has seen correspondence from one principal that states the units will be kept running at all times.
But with no carbon dioxide monitoring, Morawska said the plan for classroom ventilation remained unclear regardless of the use of air conditioners.
“I’m amazed that they pretend they are doing something,” she said.
Despite NSW and Victoria working closely together to develop a return to school plan, the two jurisdictions had different approaches for school ventilation audits.
Geoff Hanmer, a professor of architecture at the University of Adelaide and the chair of OzSage’s ventilation group, said Victoria’s approach was “not perfect” but “driven by more science” compared with NSW’s because it involved CO2 monitoring.
“If you want classrooms to be safe then you need to check ventilation, which means measuring using a CO2 monitor,” he said.
“If people get this wrong the consequences are quite serious. There’s been a tendency to want to believe that schools are not a place where Covid spreads despite all the evidence to the contrary.”
NSW is currently conducting a pilot program using CO2 monitors in some public schools across metropolitan, regional and NSW but the approach is not widespread.
In Victoria, the state government gathered data from a range of ventilation assessments across 100 schools that comprised a representative sample of different building types, including the use of CO2 monitors, to determine ventilation.
After the audit, the state government delivered 51,000 air purifiers to schools on a needs basis.
NSW Labor’s shadow education minister, Pru Carr, said the government had “provided no proof that they actually know whether ventilation in schools is sufficient”.
“Education Minister Sarah Mitchell and School Infrastructure NSW gave school communities assurances that the ventilation audit undertaken was comprehensive. It’s unclear then why significant changes to some room capacities were made and reports altered,” she said.
“For schools without openable windows, there are also concerns that air-conditioning systems now being used are not filtered to prevent COVID-19 from spreading.”
A department spokesperson said its ventilation and “asset use” was informed by NSW Health advice, research from the Doherty Institute, guidelines from the World Health Organisation and independent, peer-reviewed advice from building services consultants Steensen Varming.
“The ventilation guidelines from the World Health Organisation for Delta are appropriate for the Omicron variant,” the spokesperson said.
