There is an increasing awareness around the world of the effects fine dust particles have on public health. Japan is no exception. Although particle levels are usually lower than in Europe, the Japanese public are still very aware of the dangers posed, both at home and abroad. In fact, you have probably seen Japanese tourists with masks on their faces. Just to be clear, they are not ill or contagious but are just concerned about pollen levels in the air. In Japan, pine trees cause a lot of allergies in the Spring and studies by the Tokyo city government have shown about half (48.8%) of the population exhibit the symptoms of hay fever, five times more than in 1985.

view of Tokyo

Air quality below ground

But it is not only pollen that causes problems. MANN+HUMMEL Japan have been working with Keio University in Yokohama, which has been researching into air quality in subway stations. This is one of the first studies in the world to measure particulate matter in underground stations. With the co-operation of Yokohama city government, which owns and runs the public transport system, the University monitored PM2.5 levels at various locations within the station (entrance above ground, ticket gates and platforms) across typical working day (18 hours).

Shinkansen in Tokyo

Dust levels high at rush hour

The results of the study were very interesting. Overall, PM2.5 levels were 10% higher than the environmental standard of 35ug/m3. Particulate levels on the platform also increased when trains approach and arrive at the station. In fact, levels kept rising even after the train had departed. The effect was mainly due to dust on the tunnel walls and floor being pushed through to the station when a train passes by (Piston effect). Of course, the problem is particularly acute at peak times in the morning, when trains are more frequent. This leads to a hazardous situation where helpless commuters and travellers are storming into a “subway cloud” with usually high particulate matters concentration levels at peak times.

Japanese express train

The study attracted a lot of attention with local and national media. NHK, the Japanese state broadcaster, filmed a lengthy report with the lead Professor from Keio University. There was also coverage in many newspapers, including Nikkei – the leading financial and business daily in Japan.

Japanese ticket machines

Our ideas for a cleaner station

It was obvious from the results of the research that the station’s filtration system could not cope with the high levels of particulate matter, especially at rush hour. In collaboration with the Fine Dust Eater team in Germany, MANN+HUMMEL Japan have been developing a PoC (Proof of Concept) to create a subway station with the best possible air quality and to adapt and improve trains so they contribute to reducing particulate levels.

Tokyo Central Railway Station

To achieve this goal, we have been looking at the tests on various fine dust filters conducted by MANN+HUMMEL Germany. We hope to build on that research by installing filter columns to help reduce particulate matter on the subway platforms themselves. Furthermore, we see an application for the Fine Dust Particle Filter box, which was originally designed for urban vehicles, for use on subway trains. Installed on the roof or underfloor of a vehicle, the filter draws in ambient air toretain particles. Together with brake dust particle filters which are fitted close to disk brakes and retain up to 80% of brake dust, we aim to develop trains which not only cut down on their own dust emissions but also generate fresh air when they run.

two Shinkansen

A world-wide problem needs a world-wide solution

The problem of fine dust particles in subway networks is obviously not just confined to Japan. MANN+HUMMEL are working with operators across the world to develop solutions.

a road in Kyoto

MANN+HUMMEL Japan will be presenting our PoC, including air filter solutions for rail and stationery fine dust particle filters for stations, later this year at the MTI (Mass-Trans Innovation) fair in Chiba, near Tokyo. If you would like to know more, please feel free to contact me or Jan-Eric Raschke from the FDE team.