Indoor air quality: why are we ignoring it?

PROFESSOR Lidia Morawska carries a carbon dioxide (CO₂) monitor with her at all times and wears a mask whenever she is in a public indoor space – and it’s not just about the risk of catching COVID-19.

“If it was only about COVID, I probably wouldn’t be putting all my efforts into this because, hopefully, we are towards the end of this pandemic,” Professor Morawska told InSight+, in an exclusive podcast.

Professor Morawska is a physicist by training and is the Director of the International Laboratory for Air Quality and Health at the Queensland University of Technology. She and her co-authors, Professor Guy Marks, Head of Epidemiology at the Woolcock Institute of Medical Research and Liverpool Hospital, and Professor Jason Monty, Head of Mechanical Engineering at the University of Melbourne, have written a Perspective for the MJA on indoor air quality in Australia.

• Podcast with Distinguished Professor Lidia Morawska

“I’ve been working in this field since (severe acute respiratory syndrome [SARS]) 1,” says Professor Morawska. “Since then, I have realised how big the burden of [poor indoor air quality] is on the whole society across the world and in Australia.

“In Australia, it’s estimated that poor indoor air quality costs Australian society annually about $2.6 billion. And those estimates are already old and did not take into account all the factors [in play] now.

“Looking only at lower respiratory infections, this [burden] is annually about $1.6 billion in Australia.

“Of course, by improving ventilation as best as possible, it doesn’t mean that we would eliminate all infections in shared spaces. But let’s say that if we eliminate only half of this, we are still talking about $1 billion a year.”

Although outdoor air quality is monitored in Australia via stations operated by over 170 contributors, there are no standards at all for indoor air quality.

“[Indoor air quality] is a regulatory ‘no man’s land’,” wrote Morawska and colleagues in the MJA.

“Every state has an agency which monitors outdoor air quality,” Professor Morawska told InSight+. “There are outdoor air quality standards, there is regulation, there is monitoring of compliance. And if there is no compliance to the standards, then there are actions taken to mitigate this.

“But indoors, who is responsible for the air quality depends on the type of building. The Department of Education is responsible for classrooms, the Department of Health is responsible for hospitals – then there are hospitality spaces, office buildings and retail spaces.

“It is a no man’s land because nobody owns the land. In legislative terms, the ‘land’ doesn’t belong to anyone,” she said.

Apart from particulate matter (PM_2.5) from the environment, humans emit “pollutants” every time we breathe.

“To put it simply, we need to remove our respiratory effluents (CO₂ and respiratory particles) at a sufficiently high rate in relation to their production, so they do not accumulate in indoor air,” wrote Morawska and colleagues.

“Even though the concept [of ventilation] is simple, its implementation poses many challenges … An added complexity is that there is no clear answer to the question of which parameter or pollutant should be selected as the basis for a standard targeting airborne infection transmission, and what the numerical value should be, because it is not feasible to directly monitor infectious pathogens in real time.”

Carbon dioxide, says Professor Morawska, is a good proxy.

“If carbon dioxide concentration is low, it doesn’t mean that the risk of infection is eliminated, because these two don’t quite go together,” she told InSight+.

“If carbon dioxide concentration is elevated, there’s no doubt that the risk of infection is there as well.”

In their MJA article the authors wrote that:

“One way to assess the quality of ventilation is by a visual display of CO₂ concentration: if it increases above an accepted threshold level in relation to the outdoor concentration, it means that ventilation is inadequate.

“In this way, CO₂ readings are a proxy for ventilation, and like any proxy, it has limitations. However, CO₂ sensors are now readily available, low cost and robust, and can be used in every interior in the same way as smoke alarms.”

Professor Morawska is, frankly, baffled as to why Australians don’t seem to be concerned about the quality of the air they breathe indoors.

“We are an educated society, we know how infection spreads,” she said. “If we see somebody infected with a cold, coughing and sneezing, and that person is in our vicinity, we have enough understanding to know we are at risk.

“Pre-pandemic, it was completely socially acceptable to come to the office coughing, sneezing, and it was ‘bravery’ and ‘I’m working’. And nobody seemed to worry about this.

“It’s completely something I can’t explain. Even during the pandemic, having gone through the pandemic, we are still kind of indifferent to this. Compare it to, spitting into a public fountain — everybody would jump at this. ‘What are you doing?’ How come polluting water with pathogens attracts this attention, but not air? This is a sociological phenomenon which I cannot understand.”

Professor Morawska and her co-authors called for immediate action by governments to make all new buildings better ventilated.

“Estimates suggest that investment in new generation management systems to address airborne infections would likely result in less than a 1% increase in the construction cost of a typical building,” they wrote.

“Australia already has a sophisticated building infrastructure, public health regulatory frameworks, and public health law mechanisms to support the required advances.

“All buildings, public and private, will require modernisation, which will take time, but it is not a case of building from nothing.

“We must act now, starting with setting appropriate [indoor air quality] standards.

“Will the COVID-19 pandemic, with its countless outbreaks in shared spaces lacking adequate infection control measures, be the ‘[John Snow] pump handle moment’ in Australia in relation to airborne infection transmission?”

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