Why We Need Fewer, Smaller, Lighter, Slower Cars

Got a froggy "city throat"? It might be from metal particles emitted from braking cars and trucks.

As pickup trucks and SUVs continue to take over the roads, emissions continue to increase. And not just tailpipe emissions, but we've noted that plastic particulates from tire wear are being found in the Arctic. And wait, there's more: a new study has found that air pollution from brake abrasion dust (BAD) may be as harmful as diesel exhaust.

Liza Selley of the University of Cambridge describes her research in The Conversation:

What most people don’t realise is that exhaust fumes aren’t the only cause of air pollution. In fact, up to 55% of roadside traffic pollution is made of non-exhaust particles, with around 20% of that pollution coming from brake dust. Composed of iron particles, brake dust is caused by friction between the iron brake rotor grinding on the brake pads when a vehicle slows down. This brake dust is then worn away and becomes airborne. And as recent research conducted by me and my colleagues found, brake dust triggers inflammation in the lung cells with the same severity as diesel particles.

Published by The Royal Society of Chemistry. Liza Selley et al/CC BY 3.0

The researchers added brake dust particles to macrophages, the cells that clear the lungs of debris, and found that they increased inflammatory activity and prevented the immune cells from destroying harmful bacteria.

This discovery might mean that pollution from brake dust might be contributing to the high numbers of chest infections and froggy “city throats” that are reported by people living and working in urban areas.

Selley notes that reducing exhaust emissions are all well and good, but "we need ways to reduce non-exhaust pollutants, like brake dust, too." She advises, as does TreeHugger, that "cycling or walking more, grabbing the bus or car-sharing might reduce congestion in the areas that we live and work."

As noted in our post about pollution from tire wear, and our previous very controversial post on pollution from electric cars, all of these forms of pollution are proportional to the size and weight of the vehicles. I wrote:

Bigger, heavier cars cause all kinds of problems. They consume more fuel, they cause more wear and tear on infrastructure, they take more room to park, they kill more pedestrians both by hitting them and by poisoning the air with exhaust from ICE powered cars, plus particulates from every kind of car, no matter what is powering it.

A commenter also noted: "A change in driving habits would help a lot. Watch people jack rabbit starts, and wait to slam on the brakes at the last second for a red light."

It's yet another reason to ban SUVs and light trucks in cities; they call this irritation "London Throat" but you get it in every city. As another member of Selley's team, Dr. Ian Mudway, tells the BBC: "There is no such thing as a zero-emission vehicle." And the bigger and heavier they are, the worse the emissions.