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CO2 values for corona sometimes exceed safety levels on buses or trams, VRT research shows

VRT research shows that CO2 levels on public transport are sometimes being exceeded: "We need more trains, trams and buses to spread passengers better", says TreinTramBus, the organisation representing the interests of public transport users. In times of corona, it should be avoided that many people gather together, as this may trigger high levels of aerosols which may transmit corona virus (even when people are wearing face masks or keeping a distance). 

How the research was conducted

VRT NWS took a total of 46 measurements on the train (11), tram (23) and bus (12) in late November and early December. This happened in the Brussels, Antwerp, Hasselt and Diest region during rush hour moments. 

Teleworking from home had already been imposed for at least 4 days a week but primary schools and secondary schools were still open.  

ppm levels?

CO2 values give a clear indication about the lack of fresh air (or the abundance). In open air, ppm values (parts per million) are around 450. Experts have set the safety standard indoors at 900 ppm

Higher levels boost the chance of virus transmission as ventilation is below par in combination with too many people being together. The higher ppm values, the more aerosols in the air and the higher the chance for transmission via minute drops in the air. 

The results: up to 1,691 ppm

The train rides were generally okay. Only two rides (of 11) showed slightly higher values around 1,000 ppm. The tram rides in Brussels and Antwerp had poorer results: half of the rides showed levels exceeding 900, mostly in Brussels with values around 1,200. 

However, a record ppm value was measured in an Antwerp tram that was packed with passengers and where no windows were opened. The steamy windows were not a coincidence as a value of 1,691 was measures. 

Bus rides after school also had poor results in general. "Although the rooftop windows were opened and passengers were wearing mouth masks, we often did not feel safe", the researchers said.  

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Bus or tram rides during rush hour often show elevated ppm levels, especially when school children are packed together. If there is one person on the bus, tram or train who has contracted corona virus, it is easy (easier) for others to be infected. 

Reactions: "Focus on ventilation!"

Experts suggested that the Flemish public transport company De Lijn would halve the number of passengers in each vehicle or carriage by boosting services. But De Lijn spokeswoman Karen Van der Sypen said that this is not necessary: "It's all about ventilation, ventilation, ventilation. It's crucial that windows remain open, even during winter." Services can only be boosted on certain lines during rush hour. 

It is also possible to wait for a next bus or tram when you see the vehicle is packed with passengers, De Lijn adds. The organisation of commuters TreinTramBus does not agree, and says it is up to De Lijn and its Brussels counterpart MIVB to provide more services. 

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