Underground's black snot harmful to lungs

underground railway station

If you’ve ever blown your nose at an underground station, you’ll be familiar with the black dust it harbours. New research from our BRU shows this dust can get inside lung cells and may aggravate conditions like asthma.

Southampton researchers have shown that black dust taken from an underground railway station in the Netherlands can cause lung inflammation, increasing the risk of triggering an asthma attack.

Not just harmless dirt

Black dust found at underground railway stations, more formally known as ‘particulate matter’, is a major health concern. It is estimated that, on average, it reduces the life expectancy of each person in Europe by almost a year.

The study, published in Toxicological Sciences, involved researchers in Southampton and the Netherlands. It found particulate matter can get deep inside lung cells and set off an inflammatory response, adding to a growing body of evidence showing this dust could be harmful to our health and may be particularly dangerous for those with an existing lung condition. 

Breaching the barrier

The researchers collected the dust from a major railway station in the Netherlands. The station lies in the middle of a 5.1km long tunnel under an airport, and is used by around 60,000 passengers every day, reaching 150,000 at weekends.        

When they added this dust to lung lining cells grown in the lab, they saw the dust particles become deeply lodged within the cells. This was still the case when the cells were coated with the lungs’ protective mucus layer, which normally acts as a barrier to catch any dirt and debris we breathe in. While plenty of dust particles got stuck in the mucus, as they do in your snot, some still got through.

Once inside the cells, the dust particles caused the lung cells to produce inflammatory compounds - a distress call to the immune system. If this occurred in a person, it could cause their airways to swell up and narrow, with potentially serious consequences in an asthmatic.

Dangerous dust

Whereas dust normally contains very little metal, the black dust at an underground station has an unusually high iron content. The researchers demonstrated it was this that caused the lung cells to react as they did.

In this way, they not only showed that particulate matter from an underground station could pose a threat to someone with a lung condition, but also demonstrated the mechanism by which lung inflammation could occur, explaining how this apparently innocuous back dust can harm our health.   

Posted on Thursday 16 June 2016