Researchers are calling for a “paradigm shift” in indoor ventilation systems to combat COVID-19 and other airborne pathogens.
Since the 1800s, scientists have pushed governments to overhaul water supply systems for cleaner, safer water to stop the outbreak of waterborne pathogens. Today, researchers are calling for a similar “paradigm shift” in indoor ventilation systems to combat COVID-19 and other airborne pathogens.
Evidence of surface sanitation has popped up everywhere amidst the global COVID-19 pandemic. From a dramatic increase of hand sanitizing stations to cashiers wiping down the checkout belts and card readers, to waiting areas closed and replaced by a text notification when your exam room or table is ready, public spaces have made drastic efforts to reduce physical contact with the coronavirus pathogen.
Yet as scientists have warned of the deadly virus spreading through the air for over a year, nothing has widely addressed the need for air quality control.
Air-quality expert Professor Lidia Morawska and 39 researchers from 14 countries published a call for change in Science.
“There is great disparity in the way we think about and address different sources of environmental infection. Governments have for decades promulgated a large amount of legislation and invested heavily in food safety, sanitation, and drinking water for public health purposes. By contrast, airborne pathogens and respiratory infections, whether seasonal influenza or COVID-19, are addressed fairly weakly, if at all, in terms of regulations, standards, and building design and operation, pertaining to the air we breathe,” the paper says. “It starts with a recognition that preventing respiratory infection, like reducing waterborne or foodborne disease, is a tractable problem.”
While a nationwide overhaul of air filtration sounds costlier than our economy can bear, Morawska argues that we cannot afford the cost of control. The global financial damage from COVID-19 has been estimated at $1 trillion per month. Cleaner indoor air wouldn’t stop at fighting our current pandemic. It would also help lower the risk of all airborne respiratory disease. The annual cost of influenza in the US is approximately $10.4 billion.
“No one takes responsibility for the air,” Morawska said. “It’s kind of accepted that the air could be of whatever quality -- containing viruses and pathogens.”
The Science study calls on WHO to extend air quality guidelines to cover airborne pathogens, for building ventilation standards to include higher airflow, filtration and disinfection rates, with monitors that enable the public to gauge the air quality of the space.
Morawska says that whether we breathe, speak or sing, concentrations of aerosols are created in a “cloud” like effect.
“This cloud which stays around in the air may contain the virus. And if that’s the case, they stay suspended in the air, and they can stay suspended in the air for quite a long time until they are somehow removed from the air.
In places where ventilation is inefficient, insufficient, they... could easily stay in the air for a few hours.”
She clarifies that it depends on the air conditions as to whether or not this “cloud” would stay infectious. This type of virus prefers cool, dry air, like in an office building. Outside where it is hot with UV radiation, the virus would be deactivated in a “very short time.” Dilution is also much faster in outdoor conditions than in indoor environments.
“We should have virus-free air indoors.”
Last July, Morawska and a colleague published an open letter calling on authorities to:
- Provide sufficient and effective ventilation (supply clean outdoor air, minimize recirculating air) particularly in public buildings, workplace environments, schools, hospitals, and aged care homes.
- Supplement general ventilation with airborne infection controls such as local exhaust, high efficiency air filtration, and germicidal ultraviolet lights.
- Avoid overcrowding, particularly in public transport and public buildings.
“Most minimum ventilation standards outside of specialized health care and research facilities only control for odor, CO2 levels, temperature and humidity. Ventilation systems with higher airflow rates and which distribute clean, disinfected air so that it reaches the breathing zone of occupants must be demand controlled and thus be flexible,” Morawska said.
“None of this means that every indoor space should become a biosafety facility, but a building should be designed and operated according to its purpose and activities conducted there, so that airborne infection risk stays below an acceptable level.”
Since last spring, masks had become the public requirement for slowing the airborne spread of COVID-19. Recently many businesses and state governments have dropped their mask mandates, now more so on the heels of the CDC’s updated mask guidance. The CDC now says that fully vaccinated individuals no longer need to wear a mask.
About 37% of the country’s population has now been fully vaccinated. But researchers are now saying that the goal of “herd immunity” is likely unattainable. The focus now is on making the novel coronavirus a “manageable threat.”
