As Covid-19 pops up in more places, the Ministry of Education and NIWA are investigating how well ventilated New Zealand classrooms are.
NIWA air quality scientist Dr Ian Longley says opening doors and windows is one of the best ways to reduce the risk of transmission of the virus.
Some schools have concerns their ventilation isn’t up to scratch though, with a handful raising issues with the Ministry of Education according to the agency.
This week the organisation has tested carbon dioxide levels in 18 rooms across three schools in Lower Hutt, Taupō and Invercargill.
“If the room is not well-ventilated, the carbon dioxide from my breath builds up and accumulates very rapidly within a few minutes to an hour, so you can tell very quickly, you can distinguish which rooms have got good ventilation, which ones have got poor ventilation,” said Dr Longley.
“The point of this study really was to establish how our classrooms are performing in terms of how well their windows and doors open and whether they can achieve the level of ventilation we need to keep the classroom safe.”
Dr Longley said wind is great at diluting contaminants in indoor environments.
“All we need to do is get a little bit of that wind, which we get for free of course and bring it into the classroom.”
Poor ventilation was a factor in some schools not returning to onsite learning in Auckland this year.
In October, Kia Aroha College principal Haley Milne told the Ministry of Education the South Auckland school has an open plan structure and is located below Auckland Airport’s flight path.
"The buildings are sound attenuated which means windows are fixed and do not open – therefore we will not be able to meet the requirements of ventilation," Milne said in a letter.
"We also have extensive ongoing issues with our air conditioning systems which have been a problem for us for years," she said.
The school is planning to reopen in the new year.
Epuni School Principal Janet Evans said she was happy for her school to take part in the study as she supported the creation of New Zealand data and detailed guidance that will help schools understand if their ventilation is efficient in classrooms.
“I was really interested to just find out about what the readings were in our school, we've got really old buildings and what that would mean for us going forward and how I can make sure that my tamariki and staff are safe in this Covid environment,” she said.
“Some windows open really well, some don't… and what do we do in the winter, what is going to look like when we can't open all the windows and doors as easily as we can in the summer?”
The Ministry of Education states on its website that suppliers are trying to sell air cleaning equipment to schools, but these products are not a substitute for ventilation.
"If you have been approached by a supplier, it’s important to understand that products on the market vary greatly in how they function, their suitability in a teaching space, quality and accuracy and where they’re ideally located," it stated.
The agency states some systems can produce ozone or other pollutants that can be harmful inside the classroom.
Ministry of Education associate deputy secretary Sam Fowler said he expects the study results to be “pretty positive.”
“It's to fine-tune our interventions in those schools to make sure we're giving the right advice to give schools the confidence in the use of those spaces,” he said.
Fowler said schools that have ventilation concerns should contact the ministry.
Experiments with a range of air equipment were carried out as part of the study in an empty classroom at Epuni School.
Dr Longley said the current indoor standard for carbon dioxide levels is 1500 parts per million.
"But international studies are showing that to reduce the risk of Covid-19 transmission, you really need to increase ventilation so that CO2 stays below about 800 ppm," he said in a statement.
It’s expected some schools may need training on how to improve classroom ventilation through measures like opening windows more regularly, while a small number may need to make property or equipment changes.
The study is expected to be complete early next year, with results set to be shared with schools.