Unventilated public transport has the potential to create multiple Covid-19 super-spreader events countrywide that will see the pandemic continue to destroy lives and livelihoods.
Many South Africans have to use public transport even though this puts them at relatively high risk during the Covid pandemic. New research by the GreenFlag Association has found ways to reduce the risk of catching the virus while travelling in public and shared transport.
As South Africa, and especially Gauteng, is in the midst of one of the country’s biggest spikes of Covid-19 transmissions yet, commuters need to understand what they can do to help keep themselves safe.
More than 15 million people travel by taxi every day in South Africa. Some minibus taxis transport up to 16 people, while others can carry up to 35 people, jammed shoulder to shoulder. Ride hailing services like Uber and Bolt are increasingly popular, and many commuters travel by train.
The GreenFlag Association, a public benefit organisation focused on promoting awareness of good ventilation in closed spaces to combat Covid, has found that public transport is the perfect environment for spreading Covid-19, especially in freezing winter temperatures, when commuters prefer to keep vehicle windows closed.
GreenFlag is working with students at the Durban University of Technology (DUT) to research air quality in minibus taxis. They have conducted various experiments to test air quality with different windows and air vents open and closed, to determine the optimal environment for safe air.
According to the DUT researchers, keeping windows closed in public places or public transport during winter will promote carbon dioxide (CO2 ) build-up in the closed space from exhaled air. CO2 acts as the proverbial canary in the coalmine, which means that as the concentration of CO2 increases, so does the risk of Covid infection. A well-ventilated space maintains CO2 concentrations below 800 parts per million (ppm)
“What it comes down to, is if you can smell something like cigarette smoke or body odour in a closed space, there is not enough ventilation, which makes it an unsafe space to be in,” says Sean Chester, CEO of the GreenFlag Association.
One of the ways that Covid transmits is through aerosols. These are tiny particles that can hang suspended in the air over long periods of time. The more people exhale over a longer period of time in a closed space, the bigger the build-up of the viral load in the unventilated space.
Studies have shown that in a stuffy, confined space, such as a taxi with the windows shut and the airconditioner recirculating air, these airborne droplets (containing viruses) from breathing and talking can remain airborne for a long time, and infect people within the entire space of the vehicle.
“One of the most powerful ways to limit the rate of Covid-19 transmission is by educating the public about the importance of good ventilation,” says Chester.
Some minibus taxis, for instance, have two airflow options via the installed air conditioning system. One recirculates the air inside the vehicle and the other introduces fresh air into the vehicle. This setting should ideally be set on introducing fresh air, rather than recirculating air. However, even that is not sufficient to keep concentrations of CO2 – and the associated viral load of Covid – below the required levels.
“Achieving that level requires that at least four windows are open including the front cabin and both rear windows. The fresh air mode on the climate control system should always be open and the fan on full ball, and passengers should always wear masks,” says Chester.
In a limited study carried out by Market Research firm, FuseFactory, for the GreenFlag Association over Facebook, between 24 May and 7 June 2021, it was evident that 74% of South African respondents understood that the risk of contracting Covid-19 was higher in a closed space with closed windows.
“The results are encouraging, but unfortunately South Africans don’t seem to be taking the message about ventilation seriously enough,” says Robert Randolph, CEO of Apex Environmental and one of the expert panellists for the GreenFlag Association.
“We want to emphasise that good ventilation is a key weapon to combat Covid-19 transmission, as the country has officially entered its third wave of infections on 6 June (based on the seven day moving average) and falling winter temperatures are prompting people to gather in closed spaces and shut off the flow of fresh air.”
Poorly-ventilated spaces help spread many airborne diseases – not just Covid-19 – but others like the common cold, seasonal influenza (flu) and tuberculosis.
“Our message to taxi operators, drivers and passengers is simple: put on an extra jersey and open the window. Also, always wear a mask.”
The same principles on ventilation apply to any other closed space, including other forms of public or shared transport, as well as offices, schools and malls.
