Ventilation, short trips can reduce COVID-19 risk in public transport

MANILA, Philippines — Proper ventilation and short trips can greatly reduce the risk of contracting the new coronavirus on buses and trains, according to a global study published this week, amid a growing consensus that taking public transport is by itself not a major driver in outbreaks.

Ventilation and brief trips are part of five key factors identified in a recent study published by the Collaborative Group for Modeling COVID and Mobility in Colombia that can help determine “a safe return to higher occupancies in public transportation operations while preventing the transmission of the new coronavirus.”

The research looked into the COVID-19 mass transit policies adopted in Japan, France, Austria, China, Germany and Singapore.

Apart from user behavior, i.e., mask-wearing and not talking on public transportation, distancing and regular disinfection, ventilation and shorter trips play key roles in reducing transmission among commuters, the research said.

Trips lasting less than 15 minutes, for example, can lessen the chances of contracting the new coronavirus, the COVID-19 agent.

“Short trips generate less exposure,” the research said. “After 15 minutes, there is now greater risk.”

Ideally, vehicle ventilation—both natural (windows) or heating, ventilation and air-conditioning systems—must also allow for air renewal at least once every three minutes to mitigate the spread of airborne droplets that carry the virus, it added.

It noted that four minutes of talking inside vehicles was equivalent to 30 seconds of sneezing.

The researchers—transport experts, epidemiologists and data scientists from different universities around the world—also pointed out that several cities and countries have adopted a specific numerical value for allowed occupancy in public transport.

Reduced capacity

In the Philippines, that number is either 50 percent (on buses, taxis and ride-hailing company cars) or 15 percent (on trains).

But the study said, “It is difficult to provide a numerical estimate that is useful for all the country’s systems and different types of vehicles, since there are many factors that intervene…”

“It is the combination of these actions that mitigate the risk,” said research group member Carlos Pardo.

It’s “also interesting to see how in many cases, transit vehicle ventilation is safer than that of residential and commercial buildings, which tend to have relatively lower rates of air renewal,” he added.

The study recommended “not to close public transport services as a preventive measure against contagion,” and instead to take “special care with periodic testing and monitoring of symptoms especially for system drivers, who due to their higher risk of contagion, mobility and occupation, may suffer more infections compared to the user population and in general.”

It also called for staggering schedules, teleworking and promoting active transport “must be permanent, even when the health emergency is overcome.”

Virus resurgence

A resurgence of the coronavirus in Metro Manila is partly blamed on the resumption of public transportation in June, with the relaxation of a lockdown to reopen the country’s battered economy.

On Sunday, the Department of Health (DOH) recorded 2,378 additional coronavirus infections, bringing the national total to 189,601.

The DOH reported that 16,459 more patients had recovered, raising the number of COVID-19 survivors to 131,367. It was the second time that the DOH reported thousands of recoveries since Aug. 16, when it announced that 40,397 patients had gotten well.

The big leaps were the results of the DOH’s new strategy of counting as recovered mildly ill people and asymptomatic patients after they have completed 14 days of isolation, counted from the time their samples were taken for testing.

Sunday’s report cited 32 deaths, raising the death toll to 2,998 and leaving the country with 55,236 active cases.

Of the newly reported fatalities, 20 died this month, eight in July, three in June and one in May.

Of the additional infections reported on Sunday, the DOH said 1,022 were from Metro Manila, 132 from Cavite, 128 from Laguna, 115 from Rizal and 96 from Cebu.

—With a report from Tina G. Santos