Ventilation is key

For over a year now, scientists around the world have tried to make the case for airborne transmission of SARS-CoV-2, the virus responsible for COVID-19. But the World Health Organization has been slow to emphasize, and act on, this possibility and its implications. While it did mention in July 2020 that “short-range aerosol transmission… cannot be ruled out,” it was only in April 30 that it updated its website — quietly at that — to affirm that “the virus can also spread in poorly ventilated and/or crowded indoor settings, where people tend to spend longer periods of time.”

In part because of WHO’s previous stand, which was itself based on longstanding, uncritically accepted “scientific orthodoxy” (Greenhalgh et. al 2021), the mainstream view in health policy for over a year was that droplets were the virus’ main mode of transmission, serving as conceptual basis for public health protocols around the world that had emphasized individual actions like one-meter distancing and frequent handwashing. Such was the dominance of this view that dissenting opinions were dismissed as fake news and even censored from social media platforms.

The WHO’s change of guidance — followed by the US CDC a week later — is lamentably late, but it is better late than never. While the debate over the relative importance of droplets and aerosols remains up in the air, there is now stronger-than-ever consensus among researchers and global health institutions alike that ventilation is an important determinant of virus spread, and thus, beyond requiring individual-level actions like mask-wearing, governments should be working to ensure good circulation of air in all settings.

Some governments have already taken steps to act on this information. Notably, Singapore’s National Environment Agency released new guidelines on May 25 that called on indoor establishments to “open operable windows and doors as frequently as possible” and provide a range of ventilation measures from exhaust fans to daily air purging, especially for air-conditioned premises.

Countries like the Philippines need to follow suit, first of all by recalibrating their policies on indoor spaces. Especially in cities like Manila that’s dependent on air conditioning, ventilation standards should be developed and urgently implemented with government support. Just to reiterate, individual-level actions like mask-wearing remain critical, but there must be corresponding institutional-level measures.

Second, the emphasis on ventilation should further underscore the importance of promoting the outdoors as a safe space, where air circulation is excellent and COVID-19 transmissions are exceedingly rare. In fairness to the IATF and some LGUs, there have been some welcome steps toward this direction; for instance, endorsing the idea of active transport and bike lanes and promoting outdoor dining. However, in many other domains, the distinction between indoor and outdoor spaces continues to be under-reflected in our policies.

Third, the risk of airborne transmission has to be communicated in culturally sensitive ways. This will be very challenging, as, unlike face shields that are tangible (the weak evidence for requiring it especially outdoors notwithstanding), we do not have local concepts that neatly correspond to this abstract idea (“nasa hangin,” as some have floated, can be confusing as we actually want people to embrace the air outdoors). But, as Prof. Michael Tan hinted at in a recent column, terms like “kulob” can convey the need for better air circulation. Also, if I may add, “aliwalas.”

Finally, governments should commit to long-term investments in clean air, greenery, and well-ventilated spaces. The reason good ventilation is so hard to find in the country is because people have come to depend on air-conditioned spaces, which in turn is, at least in part, due to the dearth of trees and lack of accessible, comfortable, open public spaces. If we are to be proactive in our public health response, while also addressing the poor quality of life in our cities, we need to pursue badly needed environmental reforms.

Science is constantly evolving, and it shouldn’t be shameful either for WHO or for national governments to change policies based on changing science. What’s shameful is refusing to change policies when the science has changed. We must embrace ventilation as a key paradigm, and in doing so, spare people from bearing an undue and disproportionate burden of the pandemic response.

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