Dirty Air

A Formula 1 car moving at race speed creates a significant aerodynamic wake — a cone of turbulent air that extends 15–20 car-lengths behind it. The problem for the following car is that aerodynamic downforce depends on clean airflow passing over precisely designed surfaces. In dirty air, that clean flow becomes turbulent and separated, and the car loses a significant fraction of its downforce — sometimes as much as 30–40% in close following distances.

The result is that a car in dirty air has to enter corners slower than it would in clean air, because braking later would push an understeering or snapping front end into the gravel. The driver is also working harder on the steering and brakes to maintain control, which adds tyre wear and temperature. They experience what feels like the car being "worse" than it was in clean air — and they're right; it is.

This aerodynamic sensitivity to proximity is one of the primary reasons overtaking has historically been difficult in Formula 1. A car might be theoretically fast enough to overtake the car ahead, but the moment it gets close enough to attempt a move, it loses the downforce that made it fast. The introduction of DRS was partly a response to this. The ground-effect aerodynamics introduced in 2022 were designed to reduce dirty-air sensitivity by generating more downforce from beneath the car than from wings.

On the delta chart in RacePace, you can sometimes see the effect of dirty air directly: a driver following closely will show a shallow delta improvement through a corner, then a much larger gain on the straight where they're in clean air — exactly the frustrating pattern of getting close but not quite through.

Use the Telemetry Explorer to compare a chasing driver's corner speeds versus the driver ahead — the downforce loss in dirty air often shows up as lower minimum corner speeds.