Public buildings must enforce cleaner air

An international group of scientists calls for the introduction of indoor air quality standards.

Australia’s 2019-20 bushfire season was unprecedented in its intensity and size. An area the size of the United Kingdom burned (59 million acres). Billions of animals were killed or displaced. Thousands of houses were destroyed. Hundreds of human lives were lost or irrevocably changed.

It was also the first time Australians really realized the importance of good indoor air quality, he says Honorable Professor Lidia Morawska from the Queensland University of Technology. “I did a lot of interviews during that time. what to do, how to protect people. The advice I gave was to close the buildings as much as you can, make sure no air comes in from the outside and if you can avoid going outside, do it.’

Professor Morawska is a physicist who has been working on air quality for more than twenty years. Conduct research on 2003 SARS outbreak, and established much of the fundamental understanding of how particles from respiratory activities (such as breathing) behave indoors. “All this knowledge, these findings made me say “well, we clearly need to do something about building ventilation and protecting people indoors from airborne transmission.”

With most people in urban and industrial societies spending 80 – 90% of their time indoors, making sure the air they breathe is clean seems like an important thing, but she says in recent years it has become more difficult to get funding bodies to support her work, “For a very long time, once the SARS-1 outbreak was over, there was very little interest in it. Getting a grant for indoor air quality was almost impossible. In 2014, one reviewer even commented that it was impossible to transmit contamination through the air!”

And then, in December 2019, the world changed.

The COVID-19 pandemic, combined with the bushfires in Australia, have put air quality and ventilation in the spotlight. “I spoke to the same journalists again” says Morawska, “But this time my advice was 180° opposite – for COVID, I was saying open everything, don’t recirculate air, be outside as much as possible.”

“I remember very early in the pandemic, seeing these huge signs that said ‘wash your hands, save lives’ and I thought, ‘this is not going to save lives.’ Within days of seeing these posters, Morawska established what is now called “the group of 36”all the leading experts in air quality and aerosols. “It was when we had the first battle to recognize the transmission of airborne infections.”

At the end, Morauska was crucial to convince the World Health Organization (WHO) and other authoritative bodies to acknowledge that the coronavirus could be transmitted through the air – or more specifically, through exhaling and inhaling virus-laden aerosols. And since then, it has continued to support the provision of adequate indoor air quality for homes, schools and other spaces.

Call to action

In a new Insights paper, published this week at Science, Professor Morawska collaborated with 42 other scientists to call for the introduction of national indoor air quality standards for public buildings. They have proposed maximum levels of carbon dioxide (CO₂), carbon monoxide (CO) and fine particles (AFTER NOON_2.5), as well as an ideal ventilation rate (measured in liters per second per person).

“Most countries do not have legislated indoor air quality performance standards for public spaces that address indoor air pollutant concentration levels.” Professor Morawska explains. This contrasts with outdoor air, where national regulations and laws dictate minimum air quality standards have been widely adopted.

For many reasons, forcing air indoors is a much more complex endeavor. Indoor air contains much more diverse range of pollutants than the outside air, though some are common to both. Natural gas boilers emit nitrogen oxides (NO_X), wood stoves produce PM_2.5, building materials emit formaldehyde, VOCs are released from paints and carpets, fire retardants are commonly added to furniture, and mold thrives in damp and poorly ventilated buildings. And then there are emissions from the occupants of a building – us – exhaling carbon dioxide and occasionally viruses and bacteria. Indoor air is also greatly affected by outdoor air (the reverse is rarely true). This diversity makes it difficult to define what “good air” actually is.

Furthermore, while cities very often have numerous monitoring stations to measure outdoor pollutants, the same cannot be said for most public buildings. And even in those buildings that have installed air quality meters, “We can’t rely on watching in one room to infer what’s going on in the next room,” says Morawska. “There are no technologies yet that can measure pathogens in real time. Really, we need surveillance in every room of any public building, which means it has to be done well, but in a much simpler, much more realistic way, because otherwise it won’t be possible.”

The three metrics that Morawska and colleagues presented in their paper can be considered useful, easily measurable proxy for all other pollutants, and the proposed ventilation rate provides a way to assess the ventilation quality of a building. The overall goal is to dilute and remove pollutants at a higher rate than they are produced to prevent them from accumulating in indoor air.

“We propose a CO₂ concentration level of 800 ppm [parts-per-million] provided that outdoor concentration is used as a basis, says Morawska. “For PM_2.5we recommend using the WHO air quality guidelines as a basis [15 µg/m³]but reducing the time average.” They have also suggested 15-minute, 1-hour, and 8-hour averages of CO levels, with 14 l/s per person as the optimal ventilation rate for an occupied room.

Achieving this may involve expensive retrofits or a wholesale redesign of public buildings – another developing area of ​​research for Morawska – but he says, the advantages are clear, “While there are short-term costs, the social and economic benefits to public health, well-being and productivity will likely far outweigh the investment in the cost of achieving clean indoor air.”