When it comes to improving air quality, the onus is on commercial operators to figure it out for themselves.

Every day, you breathe in 11,000 litres of air. You also breathe in whatever is in that air: dust, air pollution, pollen –  and viruses. New Zealand has averaged 3,000 Covid cases per day in the last week, with case numbers on the increase. As an airborne disease, most of these cases will have been caused by people breathing in the virus. 

“If you have a massive dirty glass of water, you’re not going to drink it, or even bathe in it,” says Julie Bennett, a senior research fellow at the University of Otago who studies the impact of indoor air quality on public health. “And yet people are happy to breathe pollution and virus-laden air.” 

Bennett says there are two main ways to improve indoor air quality and reduce the risk of airborne disease transmission. The first is ventilation, which dilutes the harmful particles in indoor air, making it less likely you’ll breathe them in. The second is filtration, where all the air in a room is regularly passed through an ultrafine filter to clean it, or sterilised by UV light. While viruses, including Covid, are microscopic, Bennett says they tend to be attached to larger particles in the air, and will be caught in such a filtering system. 

Air filtration and ventilation work best in tandem with more visible protective measures, like masks, says Bennett. “Masks reduce the viral load in the air, so you’re not breathing in high quantities of viruses,” she says. In places where masks can’t be used – when people are eating, for instance – high airflow and filtration can significantly reduce risk. 

But both these methods for ensuring clean air have limitations. Air filters need to be the right size for the volume of air in a room, and work most effectively if they’re placed in the centre of a room, which can get in the way. And not all spaces have equal access to windows and doors that can be opened to provide ventilation. 

Ensuring airflow in an underground bar, for instance, can be quite tricky – as Rohan Evans, proprietor of Karangahape Road’s The Wine Cellar found. The live music venue in Auckland’s St Kevin’s Arcade has little access to outside air. “We definitely spend a lot of time with the doors open in the bar room to create a through-flow from the arcade,” Evans says.

He started improving the ventilation in the building back in 2015, but funding available for live venues after the first lockdown allowed him to install extra air conditioning in both of the venue’s main rooms. “The context of the pandemic made it more important to make as much of a difference in ventilation and movement of air as we could,” he says. 

While private businesses are currently given little to no guidance by the government on how to make sure the air in their premises is clean, keeping staff and customers safe makes good business sense, says Jane Arthur, co-owner of Wellington’s Good Books bookshop. Arthur has purchased air filters for her space, made a policy of keeping the door open at all times, and provides staff with high-quality masks. “Our business doesn’t exist without our staff, so a lot of the measures are about trying to protect [them],” she says. “It’s not cheap, but it’s a health and safety necessity – protecting our staff lets us keep the doors open so the money can keep rolling in.”

This stance has received positive feedback from customers, too. “We’ve had people come in and say that they’ve been too nervous to go anywhere for months but knew that if they came here the risk wasn’t so high,” says Arthur.

Despite the benefits of cleaning the air, filtration can be expensive. Even small HEPA filters can be several hundred dollars, and the filters inside them need periodic replacing. “Ventilation is free,” Bennett notes; it’s simpler and cheaper than filtration (although buildings like apartments have less natural airflow, so often require air conditioning and ventilation systems to be installed while they’re being constructed). 

While there has been some government support for schools to improve ventilation, providing CO2 monitors and air filters, and even fixing window opening mechanisms, commercial operators are essentially on their own. A page on the Unite Against Covid-19 website lists the benefits of ventilation, and notes that buildings with HVAC systems have to maintain ventilation as part of building Warrant of Fitness inspections. 

Maybe policy for air quality can change. Arthur undertook considerable research to figure out what size of filter to get for her business in Wellington; she also uses a CO2 monitor. Even if the government doesn’t fund ventilation, she thinks providing tools for businesses to assess how much ventilation their space needs could be helpful.

Another policy intervention to put ventilation on the radar would be mandating indoor air quality standards, Bennett says; Aotearoa currently has standards for pollutants outside, but not inside. This could have benefits that go far beyond the pandemic. “Improving air quality and reducing CO2 concentrations can go a long way to improving productivity and reducing other disease transmission too,” she says. 

While there are complexities to setting up ventilation and filtration in indoor spaces, Arthur says that with a little research, it’s pretty simple – and definitely worth it. “I walk past other shops and the doors are closed and masks are off and all I see is breath now,” she says. “It’s like – just open the doors! Get some airflow! It’s easy!”