People wearing protective suits cleaning cabin in airplane to prevent spreading of Coronavirus

As Covid-19 numbers hit their highest levels since the pandemic began, the U.S. faces a problematic holiday season. Despite the risk, many people are traveling in ways that inevitably put them in close proximity with others.

Many transit companies have established frequent cleaning routines, but evidence suggests airborne transmission of Covid-19 poses a greater danger than surfaces. The virus is thought to be spread primarily by small droplets that hang in the air and larger droplets that fall to the ground within six feet or so. Although no mode of transportation is “completely safe,” there are ways to significantly reduce risk.

Airplanes

While air travel – which puts dozens of people in a confined space for hours at a time – seems dangerous, many planes use high-efficiency particulate air (HEPA) filters that capture more than 99% of particles in the air. Many airlines also now require passengers to wear a mask during flights (except for mealtimes), some are blocking off middle seats to allow more distancing, and rigorous cleaning procedures are being implemented between flights.

When flying, COVID risk comes down to how closely one sits to other people and for how long, whether or not everyone is wearing a mask, and how infectious passengers are at the time. If you are seated close to a person actively “shedding” the virus, especially on a long flight or that person is not wearing a mask, there is a higher chance you will get the disease. If you are seated relatively far from others, and everyone is wearing a mask, your risk is probably fairly low. Being in a crowded airport could be a bigger concern, actually.

Subways & Trains

As Covid-19 tore through New York City last Spring, some researchers blamed the city’s subway system, which carried 5.5 million commuters on a typical pre-Covid weekday. But later reviews of the evidence suggest mass transit systems have not been major drivers of viral spread. A September report by the American Public Transportation Association (APTA) examined the coronavirus’s spread in cities with a robust public transit system and found no correlation between mass transit use and transmission of the virus. The report suggested that commuters should reduce risk by wearing a mask and staying six feet apart, and that train cars should be well ventilated. Most major cities’ subways and trains constantly recirculate a mixture of fresh air and older air, both of which are pulled through a filter rated on the MERV (minimum efficiency reporting value) scale. MERV-13 filters are less efficient than HEPA filters, but the U.S. Environmental Protection Agency recommends them for reducing airborne viral particles.

Buses

Many buses have HVAC (heating, ventilating and air-conditioning) systems similar to those on subways and trains, with one additional factor: buses are more likely to have windows that open. Windows, as well as open ceiling vents, allow fresh air to enter the vehicle. Buses also make frequent stops, allowing outside air to flood in each time the doors open. In a case study of a bus in China, a passenger with Covid-19 infected many other riders, including those seated up to seven rows away. There seemed to be less risk of transmission, however, for people who were seated near windows and doors that could open.

In addition to window seats, bus riders should look for the same safety features they would on a subway: a mask requirement, good ventilation and adequate spacing between passengers. Limiting rides to short trips may also be helpful.

FHVs & Taxis

Before the pandemic, many people didn’t think twice about sharing a ride with a stranger to save a few bucks – but now the idea of being in an enclosed space with a stranger can seem overly dangerous. Keeping the windows open and making sure the air system is set to “fresh air,” rather than recirculated air helps reduce risk. Wearing a mask also helps, when drivers and passengers do so. Some drivers have installed partitions between the front and back seats, which also helps.

Shorter rides – especially those under roughly 15 minutes – pose a lower risk than long ones. And keeping conversation to a minimum also reduces the danger because talking is known to release aerosols that can spread the virus. Taking an occasional taxi or FHV is not a huge risk, provided drivers and passengers wear masks and keep the windows open as much as possible.

Source: Scientific America