An Inconvenient Truth: COVID-19 Spreads Through Indoor Air
By Greta Fox
27 August, 2020
COVID-19 is an airborne virus. Airborne transmission, particularly indoors, turns gatherings into super-spreader events. Many months into a deadly, society-disrupting global pandemic, which as of this writing is killing an American every 80 seconds, indoor air quality engineering is finally starting to get more play in the media, but why isn’t it front and center in the requirements for essential services and their guidelines to make opening schools and business safer?
The CDC advises that it is more likely to be transmitted from person to person than from surface contact, but they do not place enough emphasis on managing indoor air quality. Masks, hand hygiene, surface disinfection, social distancing, avoiding crowds, testing and contact tracing are all essential to the creation of green zones. But the hard truth is that these measures are not enough, partly because no one measure is 100% effective, but also because they’re not always possible, and because it’s not realistic to expect a socially divided, economically stratified society to universally, consistently adopt and follow them.
Halfway measures are not cutting it. Symptom screening and temperature checks are less than 50% effective. Testing in theory is a major piece of the solution, but testing is still a mess. There is no efficient system in place for timely results, and no clear data on how long after exposure the virus will show up on testing. Tests are far from accurate, with a false negative rate of 30%, and we don’t know how long immunity lasts in those who recover. Mixed messaging about wearing a mask “when social distancing isn’t possible,” rather than a clear message that both are necessary together, is creating confusion. Six feet of separation substantially reduces the spread of large droplets, but even though we know that it is much less effective for smaller aerosol droplets, it remains the standard. We know that speaking, singing, and even just exhaling, produce aerosols, and that aerosol plumes can linger for hours, likely in direct proportion to occupancy and in inverse proportion to ventilation mixing. And just to make it really interesting, they can travel and carry viral content for tens of meters. Mask wearing, which has become shamefully politicized, is essential for reducing droplet and aerosol spread, but aerosols will leak, and the more time more more people spend gathered indoors, the more virus will be in the air if infected individuals are present. Opening a window is not always enough, and it’s not always possible.
As a nurse practitioner, I’m hoping a vaccine will be possible and effective, but it may be a long time off and is not guaranteed. But even a vaccine is only one tool in the toolbox. Science tells us that the vaccine may not eradicate the virus, so we need even bigger tools. Air quality measures are key: Updating and properly maintaining HVAC systems, use of HEPA filters and UV-C technology, setting and maintaining standards for air flushing and purification based on occupancy, should be government mandated and supported.
This pandemic is out of control. Reducing indoor airborne transmission is a major missing piece. Until we face this, the sacrifices of quarantine are wasted if we cannot safely reopen and operate schools, universities, office and public buildings, hotels, restaurants, event venues, places of worship, public ground and air transportation, or even health care facilities, where health care workers wearing PPE (when they can get it), as well as patients, are getting infected.
We are facing an ultimately unsustainable cycle of failed phased re-openings and lockdowns, with ever-dwindling reserves as both human resources and supply chains are exponentially disrupted. Meanwhile the CDC, NIH and WHO call for more research. I call bullshit. Just how precisely do we need to differentiate between surface and airborne transmission of COVID-19 before we act, and how many more people will sicken and die in the meantime? While you were reading this, two people died of COVID-19 in the U.S. “It is scientifically incongruous that the level of evidence required to demonstrate airborne transmission is so much higher than for other transmission modes (Morawska et al, Environment International, Sept 2020).” We have enough evidence, and we have the technology to do this now.