Dust In The Wind

I did it once, let me see if i can do it again. But now, i'm no mood to make calculations.

Aproximately, how much weight brake rotors loose by wearing off? A quarter of a pound every 50 thousand miles would be fair? An average car front rotor is 10 pounds. 5 percent? Seems too much. Let's say 2.5%, a quart of pound of metal. Seems about right. It matches what i remember since i made the calculations.

I've been working at Les Schwab and resurfaced brake rotors. You can do that 2-3 times for a rotor and the rotor loses like 10% of the thikness in it's life time. But the rotor, besides disk, it has a bigger piece of metal in the middle that does not wear out.

Conservatively, i'd say a brake rotor looses in 50 thousands miles a quarter pound of metal just for braking. About the same for the pads. By 4 that is a pound of dust, plus ceramic and other stuff, including asbestos for older cars and some after market pads. So almost a pound of metal (heat resistant alloys, that contains, besides iron, up to 10% of all kind of heavy metals including chromium) per car per 50 thousand miles or the interval between two brake jobs.

In a city like Portland there are 2 million cars running an average of 20,000 miles per year. That is 40 billions miles per year. Divided by 365, we get 109 millions miles per day. Divided by 50,000 we get approximately 2200 brake jobs a day, with the same amount in pounds of dust metal and other good stuff released in the air (not talking about resurfacing but actual braking).

One metric ton of very fine, microscopic, heated, partly un-oxidized, metal dust released in the air in the whole Portland area. Is it much? Is it little? I'd say anything above zero in that category is too much.

But think about tires and road wear-out. How much asphalt dust, rubber dust? How much asphalt dust a studded tires car creates in a season?

Portland is kinda lucky because of the rain. During rain season much of this is washed out down the drains, into the river and into the Ocean. One ton of metal a day just from Portland.

That's why leaky oil pans, unburnt oil and fuel are good. All this stuff acts as a dust binder (including for mineral dust from insulation in the attics of houses near streets) and traps lots of it. However, in time it flies away from under the car, drys out but some gets trapped in the soil around streets and again into the drain. And let's not forget that engine oil contains as well high alloy metal and when it burns, it releases it... Fine metal in oil that does not oxidize and when burned, it is partly in metallic state.

That's why i think it's not a good idea to eat stuff grown in the cities or around busy highways.

Don't ask me what a good idea is to blow it with blowers on the sidewalks or parking lots.

With newer cars, less leaky, with catalytic converters that turn everything into CO2 is even worse. No binding of the dust. The hope comes from electrics and hybrids that do not use classic brakes except for failure of the regenerative braking system (turning braking energy into electricity and store it back in the battery). Smaller with smaller tires.