Cape Town International Airport (CTIA) is dead quiet as South Africa enters the third wave. The engine of one of the world’s great tourist destinations, it has fallen victim to the Covid-19 pandemic. My first flight in over a year is from CTIA to my birthplace, Harare, a dusty and damaged city. A melancholy trip in a melancholy time.

International air travel has resumed, at low levels, and all passengers must show a negative Covid test, but many are wary. Is it safe to be in a “tin can” 30,000 feet up for several hours, with dozens of other passengers in close proximity, breathing the same air? Airlines claim it is. One reason is that modern passenger jets are equipped with systems that circulate the air through filters multiple times per hour.

To enter CTIA you must pass through the thermal scanning station. Is temperature scanning an effective form of screening for Covid-19? Not really. It’s unreliable and a US CDC report last year disclosed picking up Covid in only one in 85,000 travellers screened at American airports in highly resource-intensive screening programmes.

With only a few people in the airport — a large building — and all wearing face coverings, you are unlikely to acquire Covid in the check-in, arrival or departure halls. I whip out my carbon dioxide (CO₂) meter (also measures temperature and relative humidity) and confirm low CO₂ levels, around 450ppm (parts per million). As President Cyril Ramaphosa has pointed out, avoiding Covid requires good ventilation. CO₂ levels reflect the amount of exhaled air that is being shared by people in an indoor space. CO₂ meters are portable and relatively inexpensive. The ventilation in CTIA is good, so far.

Through customs and emigration, the departure hall has been largely emptied of seating. This is irrational, as Covid-19 is rarely transmitted by contact surfaces. Spacing lines, and seats — to space people — does make sense.

The bus from terminal to plane does not depart until every passenger is on board. We are packed in, mostly standing, all 30 or so passengers. Perhaps it would make sense to run two buses. But, the windows are open to fresh air and the CO₂ level is fine. On a short ride, this can be no worse than travel on the New York subway where ridership has shown no relation to Covid-19 infection rate.

On board, the crew give us each a tiny, packaged antiseptic hand towel. Maybe these are talismanic. One assumes the plane has already been sanitised, between flights.

My companion and I had chosen seats up front — 7A and 7B. Because Covid is airborne, being close to doors (and windows) is a good idea. The aircraft door is shut and we taxi for takeoff. The CO₂ level rises — past 800, a useful threshold for safe indoor spaces, to 1,200 and all the way to 1,800 by the time we are off the ground. We are breathing quite a bit of other people’s air — potentially containing SARS-COV-2 (or other germs), but are wearing Korean KN94 consumer masks with good filtration properties that fit us well.

We look to the back of the plane, noticing that about 80% of passengers are seated in the front half of the plane. We rise and move to a back row, as far as possible from other passengers, where the CO₂ level is only about 650. From a Covid point of view this seems to be a safer place to sit.

During the flight, frequent announcements remind passengers to keep their masks on, covering nose and mouth. Most comply, except when eating the boxed packed meal of course, but some have masks that fit so poorly it’s almost impossible for them to do so, even if they were willing. Shouldn’t airline staff check this safety equipment before take-off the way pilots check other crucial air safety systems?

The number of people who have acquired Covid while flying is not fully established. There have been several published reports and the rate quoted overall is one in 27 million. It’s hard to know if the disease is acquired during arrival or departure procedures, queuing in crowded spaces, or on the plane. Viral genomic (RNA) analysis can help to determine who got Covid from whom.

Arriving in Harare, formalities are strict; we have to fill in four different forms all covering more or less the same information. Symptoms of Covid are inquired about and we must show the result of a PCR test obtained within 48 hours of departure — R850 out of your pocket. But can the authorities tell genuine from fake test results?

The return trip five days later is similar. Another Covid test! Ironically, Zimbabwe has vaccinated four times more people than SA, per capita. At Harare airport’s entrance, a man carrying a large nondescript can directs its connected tubing and nozzle to ourselves and our bags. Clear liquid of uncertain nature coats the suitcases. We object, but it’s too late. Fumigating and fogging are discredited as methods for prevention of Covid, but probably quite profitable for the fumigation vendor.

The flight home again sees the plane unoccupied at the rear so we head there. From door closure to airborne, the CO₂ level rises to 950, then reduces.

On patrol up and down the plane I measure the CO₂: around 1,200ppm up front, where more occupied, 650 in the back. A passenger is curious, he wants to know what the device is; it resembles a brick cellphone from the 1980s. I tell him the CO₂ level is just about normal. I don’t want a stampede to the rear! The crew are mystified and not a little suspicious.

Saturday afternoon and our flight provides the only passengers in the sad and forlorn arrival hall at CTIA. The Department of Health form asks which seat we occupied and whether we changed. Information used in contact tracing?

This was a trip during which we were unlikely to contract Covid-19. Airlines and airports are trying hard to protect us, but could make a few changes. They should ditch the spraying of baggage while ensuring and monitoring ventilation (air exchanges per hour, air filtration, CO₂ levels) and that decent quality masks are properly worn. Thermal scanning has only ritual value. Screening is expensive and ineffective; requiring Covid tests might be all that’s worth doing. Airlines could space passengers better via online seating or after boarding.

Covid-19 transmission during air travel occurs, but is rare. Tourists, please come back. Especially those from highly vaccinated countries! DM