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Comment by stuaxo | Hacker News Reader

I've needed my inhaler way less since the ULEZ came in.

Visiting London used to mean blowing your nose to black snot for a week afterwards, these days living in London it's pretty good.

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ULEZ massively reduced the amount of NO2, which is a trigger for asthma. It also seems to have reduced the hospital admissions for heart related emergencies.

Sources:

https://www.bbc.com/news/articles/c75q9d2pqyeo https://www.theguardian.com/environment/2026/jun/12/emergenc...

I've not lived in London for more than a decade. I always thought the black snot was from the Tube. Is it not?

It is, but not just from it.

I lived on Upper Street in Angel, London by some traffic lights and there was always a layer of black dust inside. I assumed it was brake particulate.

Every house inner London is covered in black soot from the days of coal fires. Have you ever seen one after it's been sandblasted?

Tire wear was probably a greater source than brake wear.

I've lived in London all my life and I only get black bogeys on days that I've been on the tube. Before COVID that was every day.

Yup, especially on the older lines (Northern, Victoria, Jubilee, Bakerloo). Particulate pollution can be two orders of magnitude higher than at street level. This tends to be glossed over when trumpeting the success of ULEZ measures pushing people away from cars and onto public transport, and I say that as a non-car-owner.

People tend to walk 10-15 mins at either end when taking the tube, and will walk more through the day. My understanding is this activity is net positive despite the extra particulates while on the tube. I might be misremembering this with a study I read on cycling in road pollution though

Almost certainly some asbestos dust still in there from prior decades as well, the tube is absolutely filthy and never cleaned properly

Indeed.

https://www.theguardian.com/uk-news/2026/jul/18/london-under...

Just one more reason to wear an N95 on the Tube.

Oh yeah "tube bogeys" are definitely a thing.

Whenever my best mate goes on about having access to "cultural experiences" that I don't have for living in the sticks I remind him it comes at the cost of massive tube bogeys. :P

Anecdotal, but similar situation here for me (I don't need an inhaler, but visiting London around 2015 meant blowing my nose to black snot for a week, and then back in 2024 it was completely fine)!

More anecdata: I've been using my inhaler more since moving to a city with worse air quality than my previous location.

Pretty sure that's due to the tube.

What's so uniquely bad about the tube in London? Poor ventilation and brake dust?

Its the oldest metro in the world. An achieviement, yes, but in old stations ventillation is crap, materials are poisonous, etc.

Yeah, seems way better now than it was in the 90s though. They’ve improved the ventilation a lot.

People don't fire their chimneys or have garden bonfires much any more, either.

Tell that to Germans. Winter air here is extremely bad.

Rising natural gas prices due to the Ukraine war also made even more people install fireplaces (as if that was cheaper).

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