The re-opening minefield

I asked a gathering of fictional characters what they were doing to minimize pandemic re-opening hazards. The conversation had a lot of one-upmanship about risk, so I’ve rearranged the order of topics from highest risk (kissing) to what I consider the lowest risk (solo running).

1. “Kissing? I’ll bet it is the most efficient way of delivering the thousand virus copies needed to start an infection. And it’s not just open-mouth kissing, either. Touching lips will suffice, as someone’s upper lip ridgeline catches nasal outputs that their previous sniffle didn’t hold back. And for this coronavirus, nasal drips are virus-laden several days before symptoms begin. Blowing kisses from a distance will come back in style.

I guess that kissing is okay if you are sharing a bed with someone — and already sharing their microbiology. Family’s okay to kiss, but not extended family — that’s my motto. Maybe we ought to ration kisses. That will make a kiss much more desirable.”

2. “Cheers and shouts? I suppose, if you are trying to infect your companions, shouting is less efficient than kisses — less direct delivery, but the shower of invisible saliva droplets from that person behind you in the bleachers can do the job, as one droplet easily contains 1,000 virus copies, and you have several hours to catch one. There was recently a super-spreading event from a curling match in Canada. One-third of the people contracted Covid-19.

No more crowded sports events for me. Until they switch to requiring cloth face masks for spectators, to catch those outbound droplets, my sofa is safer. I don’t have to worry about loud-mouth splatter, only about the microwave burning the popcorn.”

3. “Singing in a choir may be worse. Remember those news stories about choir practice, when one person infected 52 others — 87% of those in the same room? And the choir was already taking standard pre­cautions for the time: stay home if feeling a bit off, no hugs and kisses, no handshakes. But singing for 2.5 hours did the job anyway.”

4. “I think we will needWhisper in Confined Spaces signs in the elevators and similar sardine cans. The vocal cord vibrations create a lot of tiny air bubbles inside the mucus that contain virus aerosols. Quiet breathing generates some, but speech generates a lot. You have probably seen those news stories that say viruses can linger in the air for more than 14 minutes after talking stops — but that is in the still air of a small test chamber. With ordinary air turnover in a large room, that cluster will disperse. Elevator fans need to be set on high, and vocal cords set to whisper.”

5. “That reminds me that noisy dining rooms are a big problem because others at the same table must raise their voices, creating four times more droplets in their air stream. And when that fails, they lean toward you to shout their third repetition of what they originally said. And so the dining room becomes even noisier.

Cohabiting pairs and family members already share their risk and so dining out together may be acceptable, even when dining with co-workers adds risk. Sitting at an outdoor table may improve the ventilation problem, but it may be just as noisy because of nearby traffic.”

6. “After decades of good-for-alcohol-sales advice to make their indoor spaces noisier with piped-in music and hard surfaces, restaurant and pub owners are going to find themselves finally doing what the hard-of-hearing seniors have long requested: installing soft surfaces (wall hangings, carpets, partitions, and acoustic tiles on the ceiling).

Nice quiet booths are going to be in high demand, even deemed essential in retirement communities and assisted-living facilities, where infections are more likely to have deadly outcomes simply because people are over 65.”

7. “Noisy workplaces have the same problem. That’s likely one reason why meat-packing plants have so many Covid-19 cases: the room is sufficiently noisy that workers have to shout at one another, plus they work in cold rooms that have minimal room air turn­over, to save money on re­frigeration. Viruses survive much longer in cold air. There are now outbreaks in 115 such plants with 5,000+ workers infected and 20 dead. Time for better OSHA regulation. Workers may need hoods with filtered air piped in, plus audio links to coworkers.”

8. “Airplanes are much like the meat-packing plants except for losing the refrigeration hazards: they are noisy, encou­rag­ing shouting, plus they minimize air turnover to save fuel. One of the first super-spreader events was in 1977 when one passenger managed to infect many others at the far end of the plane, likely while awaiting takeoff clearance, with the ventilation shut down. When turned back on after a three-hour wait in stale air, air flow probably moved a dense aerosol cluster around the plane.

Packing density is their other problem; an empty middle seat and maximum air flow rates without much recirculation, masks mandatory, would seem the bare minimum that the airlines must do to attract riders back. Employees traveling regularly ought to get combat pay as soldiers do.”

WHC: I can imagine personal masks with an adaptor tube that fits over the usual pressurized air nozzle overhead. It won’t protect against the recirculating aerosols, but it would allow you to avoid those virus-containing droplets from people seated nearby. The droplets cannot get inside the mask because air will always be flowing outwards from the edges of the mask as you inhale. If you can keep your mouth shut, then the nose-only CPAP masks will work.

Twisting the air nozzle ought to provide a comfortable pressure. All we lack is an adapter that will fit the usual CPAP air hose to the nozzle, maybe with a clip to keep it from falling off.

9. “Indoor conference rooms are not quite as bad as choir practice, because not everyone has a loud voice at the same time. Remember that the table surface is going to accumulate the larger droplets that would have settled to the floor.”

10. “Hugs without skin contact still get you too close to another’s exhaled droplet cloud, which is denser if they are speaking while hugging. One invisible droplet contains more than 1,000 virus particles. Weddings, funerals, and birthday parties were 10% of early spreading events for the coronavirus.”

11. “Parties and after-hours gatherings. Reinvent them. Start by moving outdoors. Four chairs around a big table that seats eight. Gather under a waterfall. A large shower stall might do; a really fine spray setting on the shower heads ought to sink those virus droplets generated by conversation. Keep a hand over your wine glass.”

12. “Public transit presents multiple ways to convey 1,000 virus particles. The air-turnover-rate standard for transit vehicles is much lower than for workplaces, and so virus aerosols accumulate in the air that is breathed, despite a mask. Touch surfaces are heavily used. The nightly wipedown may minimize the problem on the early morning commute but not on the afternoon return. And, because it is so noisy, conversations are loud.”

13. “Note that all bets are off if someone sneezes. Allergy season can increase your coronavirus risk. The air stream may start out at 200 mph and carry the smallest droplets clear across the room. As they evaporate water en route, the tiny air bubbles within the mucus droplet will pop, releasing virus aerosols that will linger at face height and that your cloth mask will not filter out. But otherwise, the spread of the disease involves infectious droplets in the airspace around you and smears on the surfaces that you touch.”

14. “Uh, guys, we’ve missed the hard ones. Classrooms? Recess?” No good answers, but see my earlier piece on re-opening strategies for research universities.

15. “And we missed Public Restrooms with all of those surfaces to grab (use your elbow), and also high hourly usage. You might be alone in the restroom but viruses from several hundred previous visitors may be lingering. There is also a special aerosol hazard generated by flushing toilets without a covering, typical of workplaces, despite OSHA. At home, one can at least lower the lid before flushing.”

16. “Floors accumulate the heavier droplets and get they tracked around. Even if you avoid touching the floor, you may touch children or pets that frequent the floor.”

17. “Solo running has almost no hazards by itself, but running partners add some risk when speaking loudly, and those stampedes of runners are bad form by any standard. Droplets will have settled by the time you occupy the same airspace as the runner currently ahead of you, given sufficient spacing, and while there is still an aerosol cloud left behind another runner, a very brief passage time makes it difficult to get the minimum 1,000 virus particles to start an infection. But for a droplet, it only takes one droplet with 1,000 inside; wear a mask.”

18. “Shopping with a mask and six-foot spacing still has the problem of what other people handled and put back. Viruses only infect while they are fresh; they go stale within a few days. While some may last longer, the minimal 1,000 for starting a new infection is much more difficult to achieve after several days.

Viruses do survive a long time at refrigerator temperatures, so wipe down new containers before putting them in the refrig­erator. Boxes and cans that have sat unhandled for a few days at room temperatures are probably safe.” Sterilization by neglect is not perfect, but it does allow you to focus on the more likely routes of infection.

19. “Standing around talking outdoors in the manner of dogwalkers and New York City police officers is still subject to the six-foot rule, to allow droplets to settle. Go ahead and be standoffish.” Speak softly but carry a big stick. An ordinary cane or ski pole, held horizontal at arm’s length, is about right to measure that six feet.

20. “What about the elbow bump as the new handshake? With a mask, it may be low risk because it is a very brief entry into another’s air space, and it does not involve skin that is in frequent contact with your eyes and nose. It should be difficult to acquire 1,000 virus particles even from multiple elbow bumps. But a bow or nod is even safer, and that custom is already in wide use around the world.”

So, your choice. But remember that your choice is not so much about protecting yourself as it is about protecting others from your viruses, should you be a carrier. When you omit a common precaution, you may be endangering others, rather like the chief narcissist and his imitators.

To repeat, remember that a carrier’s sneezes, whether from infection or allergy, remain a hazard in any setting, because their high air flow can project droplets up to ten steps ahead, the width of many a conference room. Your mask might protect you from the expelled droplets but when speech and sneeze droplets evaporate enough to expose the little air pockets within, the aerosols released will allow clouds of virus to linger at the right height to inhale, even through a cloth face mask.

I have rewritten the previous version of this essay because of good advice from a marketing psychologist: to be cautious about telling people what not to do, because about a third of them in any culture will interpret it negatively, as taking away their freedom of choice. And that may make doing the wrong thing more attractive. The same people, faced with something in short supply, will find that something much more attractive — a trait exploited in those “Only three left in stock” come-on messages above the lighted buy button.

For those who really want to know where the numbers come from, there is an excellent article on how viruses spread by a pro, Dr. Erin Bromage, frequently updated. It uses knowledge developed over the hundred years that virologists have been studying the influenza viruses. There may be relevant additions to the risk list here because of differences between the flu viruses and the novel coronavirus, but they have not yet been studied in any detail.

I will be updating this list using your comments and any new develop­ments, just as Dr. Bromage is doing for the epidemiology. Consider getting a fresh copy of each before forwarding to someone who needs the information.


— Will

William H. Calvin, Ph.D., is the president of and a professor emeritus at the University of Washington School of Medicine in Seattle. His 17th book is “Extreme Weather and What to Do About It.”



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William H. Calvin

President, Professor emeritus, University of Washington School of Medicine in Seattle. Author, many books on brains, human evolution, climate