I've just published my April story for @forbes. It's all about non-exhaust emissions and covers lots of recent research into their extent in our cities and their impact on our health

https://www.forbes.com/sites/lauriewinkless/2026/04/12/most-of-the-microplastics-in-urban-air-come-from-tires/

#science #scicomm #emissions

Most Of The Microplastics In Urban Air Come From Tires

Particles produced from brake and tire wear now represent the majority of emissions from road transport. As the EU cracks down on them, scientists urge others to follow.

Forbes
@LaurieWinkless @forbes does it address dogfarts and various baby emissions?

@LaurieWinkless
Good read, thank you.
Has anyone tried up quantify the amount buses and cyclists contribute compared to cars? And I'm presuming the things cyclists can do to reduce that are largely the same as for drivers- tire pressure and riding style, except that often people are replacing car trips with cycles so unless it can be realistically replaced with walking instead cycle trips are net benefit.

@forbes

@RedRobyn I've seen a few studies - I'll link below - but it will likely be a tiny fraction, especially when measured on a per capita basis. The average Bikes+cyclist might weigh ~100kg(?). A Ford Range is 2500kg+. A Metlink bus here in Welly weighs about 10x a Ford Ranger when full of passengers (they have a capacity of 110ish). Cars and trucks dominate emissions profiles in general because of their sheer numbers (and their weight), so I can't imagine it'd be any different for non-exhaust emissions
@RedRobyn Quantifying abrasion of microplastics from mountain bike tires https://www.sciencedirect.com/science/article/pii/S0048969725006060
@RedRobyn and this is a decent review - Table 1 gives numbers for different types of vehicles (incl. buses) https://www.sciencedirect.com/science/article/pii/S0048969720313358
Tyre and road wear particles (TRWP) - A review of generation, properties, emissions, human health risk, ecotoxicity, and fate in the environment

In this paper, the current knowledge on tyre and road wear particles (TRWP) is compiled regarding all environmental and health aspects. TRWP generated…

@LaurieWinkless this gives a surprisingly (to me) small difference between car and bike as they mention 3.6 vs 11 g/100 km; though maybe mountain bike emissions would be much larger than road bike... if the latter is closer to the 1.43 g/100 km that is mentioned for later stages in mountain bikes (or even lower) then it'd be a bit more significant.
Anyway, I expected the speed and mass difference to lead to more significant differences.

@RedRobyn

@tfardet @RedRobyn yep, mountain bike tires typically use much softer rubber formulations, are much larger, and have more complex tread designs than road bikes. I would be surprised if a road bike generated anywhere close to this.

@LaurieWinkless

the metal wheels on various types of rail also wear out, so those particles have to be going somewhere.

But those would be metal, not plastic, so I've been wondering what the health impacts from rail wheels might be like.

Not surprising. TY for writing this, @LaurieWinkless !@forbes

@LaurieWinkless @forbes

The most interesting part to me:

"At an individual level, car owners could drastically reduce non-exhaust emissions simply by driving better – avoiding rapid acceleration and hard cornering, anticipating stops and using gentle braking to slow down. Maintenance too makes a difference, so be sure to keep tires at the appropriate pressure, and don’t carry heavy objects unnecessarily."