“The scary thing is, I have no idea how I caught it.” We’ve all heard variants on that sentiment in recent months from those infected with Covid-19. While there is always uncertainty, and even those taking sensible precautions can be unlucky, I worry that one unexplored explanation is a widespread lack of understanding about how the virus spreads. Combined with the behavioural recommendations outlined in UK government guidance, this has led people to take more risks than they otherwise would.
While nothing in science is settled, the consensus opinion is now that Covid-19 can sometimes hang, spread, or be projected through the air for longer and further than initially thought, constituting a form of aerosol transmission (i.e. it remains airborne).
Early in the crisis, it was presumed the virus spread overwhelmingly via larger droplets – miniature drops of water that leave our mouths and nose when we talk loudly, sneeze, cough or more. That meant it could infect you by hitting you directly when too close to someone, or if you touched a surface where droplets had fallen. Hence, guidance such as to wash or sanitize hands regularly, keep 2m distance, put up perspex screens, bump elbows instead of shake hands or, more recently, to wear masks indoors.
Pretty early on, however, it became clear that aerosol transmission might occur too. Aerosols are microscopic droplet particles that hang in the air for longer after being emitted from our mouths, rather than falling to the floor. Studies of superspreading events, including in restaurants, choirs, public transport, and offices, showed people becoming infected at greater distances from the infected, as people talked or sang, or air conditioning systems pushed air around. Some studies even alluded to aerosol transmission from faecal matter.
Now, the scientific consensus is that there is more of a droplet-aerosol continuum, with airborne transmission possible and maybe very significant in certain badly ventilated settings. Distance mitigates infection risks but doesn’t prevent them. Yet, bafflingly, government guidance hasn’t kept pace with new knowledge, at least in terms of its emphasis, and may have combined with recommended behaviours to worsen risks for lots of people.
The Government’s most recent lockdown guidance began by reiterating “Hands. Face. Space”. The implicit message: if you keep your hands clean, wear a facemask indoors, and keep 2m away from people, you’ve done what you can to eliminate infection risks. Yet with indoor aerosol transmission, that’s not necessarily true. While these precautions do still help on the margin, even a mask and 2m distance will not fully protect you if you are spending prolonged amounts of time in rooms without decent airflows (see this excellent explainer from El Pais). That’s why some people are already warning of the risk of disastrous superspreading events at certain vaccine sites, where vulnerable people are herded in for 30 minutes or more to wait and be observed afterwards.
The Peltzman effect
In fact, the lack of government guidance may interact perniciously with mask-wearing mandates. In economics, we often talk about the “Peltzman effect.” Named after Chicago economist Sam Peltzman, the idea is that sometimes safety regulations, by lowering the perceived risk of an activity for the individual, actually encourage more risky behaviour to the cost of others.
Peltzman worried, for example, that mandating airbags in cars might cause people to drive more recklessly, leading to more accidents. This Peltzman effect need not overwhelm the pro-safety regulation’s benefit. What the net effect will be is an empirical question. But acknowledgement of it reminds us that by changing perceived risks, mandates or guidance can alter human behaviour.
Due to the inadequate government guidance on the possibility of aerosol transmission, I fear we’re seeing a societal Peltzman effect with mask wearing.
Granted, masks can help curb the spread of the disease at the population level. They do provide a layer of protection that can reduce the possibility of droplet and aerosol transmission and possibly even reduce viral load for those infected. But if some people think masks all but eliminate the risk of infection indoors, they may be more inclined to engage in the kind of prolonged indoor activity that exposes them to the risk of infection.
As I discuss in my forthcoming book, Economics In One Virus, public health officials feared Peltzman effects for mask wearing last year. They worried community mask wearing would give people a false sense of security, leading to less physical distancing (an effect observed in online experiments), so offsetting the first-order public health benefits of the mask, particularly if people also touched their face more, wore less effective cloth masks, or wore masks incorrectly.
I think the major Peltzman effect here is people thinking masks reduce indoor risks more than they do. This perception makes them more willing to engage in working in offices, indoor shopping for groceries, or (outside of lockdown periods) visiting other poorly ventilated households. In Britain, dine-in restaurant attendance rebounded spectacularly last summer, with people wearing masks into restaurants before sitting in busy rooms to eat and talk without them. Mobility during this lockdown has not fallen to spring 2020 lockdown levels, with workers being more willing to go into the office or spend time in businesses that are dubbed ‘Covid-compliant’.
The problem here is not so much the mask itself, but the emphasis on the government’s guidance. When I asked people I knew what they had been up to in the week before their infection, one said “only going shopping for food”, another said that her daughter “had visited for an hour, but we’d both worn masks for the full period”, and a third was going into the office and wearing a mask in communal areas. All of them seemed oblivious to the potential of infection.
The importance of being ventilated
Polling data from Savanta shows that only just over 5% of the public think the government has emphasised “avoiding unventilated indoor spaces” as the most important precaution against Covid-19 in recent months (unsurprising, given there has, to my knowledge, been only one government advert about this and it doesn’t figure prominently in regular briefings). When asked what steps people would take to protect themselves if a plumber visited for two hours, opening windows was the precaution they’d be least likely to take, compared with mask-wearing, cleaning surfaces, handwashing, and keeping a 2m distance.
It’s high time the Government strongly emphasised the risks of aerosol spread. Call it “Hands. Face. Space. Aerate”, at least until someone comes up with something better.
Rather than impose more punitive lockdowns restrictions, they should remind people about the risks of prolonged indoor gatherings, even with masks, and the importance of keeping windows and doors open when indoor contact does occur. This emphasis should include encouraging vaccine centres to take ventilation seriously, by perhaps worrying less about the the need for prolonged post-vaccine observation for relatively low probability adverse reactions. One would hope such guidance would lead some businesses to reassess whether going into the office was truly essential too.
No doubt some in government and beyond would object that there will be economic costs to such guidance, as it deters some market activity through fear. And there would be. But, as we have seen, the economic costs of a rapid spread of the disease and the subsequent lockdowns tend to be far greater.
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