Tire & Brake Dust: Roadside Pollution Simulator

Exhaust is only part of the pollution a road produces. Every tire and brake pad sheds fine particulate matter as it wears, and this simulator models where that dust actually goes: cars stream down a 3D roadway shedding a physically-scaled mix of coarse (PM10) and fine (PM2.5) particles, a crosswind carries them across the roadside verge, and each particle falls at the real Stokes terminal velocity for its size class — so the heavier grains settle near the curb while the finer ones drift much farther, exactly as measured in real near-road air-quality studies. Toggle rain on and the dust already resting in the soil washes off into the storm drain by first-order kinetics, the same pathway that carries road grime into real streams after a storm.