Anyone who has ever travelled on the London Underground will probably acknowledge that while it might be a convenient way to navigate the city, it’s certainly not the cleanest. 

As soon as you descend the escalators into the grimy subterranean tunnels, you’re hit with a wave of warm, stale and often smelly air. 

While most of us hop on and off the Tube relatively quickly, many of us use the underground several times a day, each and every day. 

So, should we be concerned about the levels of air pollution on the Tube platforms and trains? And is there anything we can do about it? We asked the experts for their take. 

In a word: yes. According to researchers from the University of Cambridge, the London Underground is polluted with ultrafine particles of metal that are small enough to enter the human bloodstream. They took a sample of dust from ticket offices, platforms and operator cabins throughout the 250 miles of Tube track and found high levels of iron oxide suspended in the tunnels for long periods due to inadequate ventilation. 

While the researchers stressed that it’s not clear whether the particles cause a health risk, they did warn that they are too small to be captured by current pollution monitors, meaning we could be vastly underestimating just how toxic the air down there is. 

“Air pollution on the Tube, particularly in underground subway systems like the London Underground, is a significant concern,” warns Ian Budd, a pharmacist and medical expert at Chemist4U. “The confined environment and frequent train movements contribute to elevated levels of particulate matter, notably PM2.5 and PM10, which are harmful to respiratory health. Prolonged exposure to these pollutants can exacerbate conditions such as asthma, bronchitis and other chronic respiratory diseases, and may even impact cardiovascular health.”

Vulnerable populations, including children, the elderly and those with pre-existing health conditions, are particularly at risk.

A combination of factors contribute to the poor air quality on the underground. Most of the lines are over a century old (the Metropolitan Railway, between Paddington and Farringdon, opened in 1863), and while we’re confident the trains have been replaced since then, most of us will have experienced some fairly rickety journeys in our time. 

“Pollution levels in the Tube are influenced by various factors such as the age of the trains, the type of braking systems used and the overall maintenance of the system,” says Budd. “Some stations and lines, especially those that are deeper and older, tend to have higher levels of particulate matter. Monitoring systems and studies have been implemented to assess air quality, and when pollution levels are deemed unsafe, it is usually based on concentrations of particulate matter exceeding health guidelines set by organisations like the World Health Organisation (WHO).”

Born and raised Londoner Tanya Beri became seriously concerned about levels of pollution on the London Underground following an operation to remove her tonsils, which she believes was triggered by exposure to harmful air while travelling on the Tube. Following her father’s death in 2021, she was galvanised to found CAIR London, an app and website that provides information on Tube pollution, including monitoring the levels of individual lines. 

“While we don’t know the long-term impacts of Tube pollution exposure as well we do above-ground pollution, we do know that high exposure to PM2.5 isn’t good for us and can contribute to serious health issues,” she tells Strong Women. “So CAIR London measures each underground station for you, so you can check before you travel. As well as monitoring air quality, we also measure sound pollution, so you can avoid the screech.”

In a statement, Lilli Matson, TfL’s Chief Safety, Health and Environment Officer said: “We understand how important it is to our customers that we are improving air quality on the Tube. 

“We are continuing to see a downward trend in dust levels on the Tube and our independent monitoring confirms they remain well below occupational health limits set by the Health and Safety Executive (HSE) and on most of our network are below the recommended limits advised by the Institute of Occupational Medicine, which are set significantly lower.”

While any improvements and upgrades to the rail system are out of our hands, there are steps we can take to mitigate the effects of air pollution on the underground. 

“To reduce the impact of pollution when using the Tube, individuals can take several steps,” advises Budd.  “Wearing masks, particularly those that filter fine particles (eg N95 masks), can reduce inhalation of harmful particles. If you’re able to do so, minimise travel during peak hours when the air quality tends to be worse due to higher train frequency and passenger density. Additionally, increasing ventilation within carriages and stations, though largely out of individual control, can significantly improve air quality.”

And if you’re really inspired to help make a change, consider using your voice to advocate for better maintenance and modernisation of the system. 

“Public awareness and pressure may prompt authorities to implement more rigorous air quality monitoring and take necessary actions to reduce pollution,” says Budd. “This includes upgrading trains to newer models with better braking systems that produce less particulate matter and improving ventilation systems.”

Images: Getty