Dirty Air

Dirty air is the turbulent, disrupted airflow left behind by a race car, which negatively affects the aerodynamic performance and grip of any car following closely behind it.

When a race car speeds around a track, it doesn't just move through the air—it actively disrupts it. The car pushes air aside and creates swirling patterns and vortices in its wake, much like the choppy water you see behind a speedboat. This turbulent zone of disrupted airflow is what drivers and engineers call dirty air.

For a car traveling in clean, undisturbed air, the aerodynamic components work exactly as designed. The front wing, rear wing, and underbody generate downforce by managing smooth airflow over and under the car. This downforce pushes the car onto the track, providing grip that allows drivers to take corners at high speeds. However, when a car enters the dirty air behind another vehicle, everything changes.

The turbulent airflow disrupts how air moves over the following car's aerodynamic surfaces. Instead of smooth, predictable airflow, the car encounters chaotic, swirling air that dramatically reduces downforce. In some racing series, a car can lose up to 50% of its downforce when traveling in another car's wake. With less downforce comes less grip, making the car slower through corners and more difficult to control.

This loss of grip creates a chain reaction of problems. The tires slide more without adequate downforce, which increases tire wear and can cause them to overheat. The car's handling balance shifts, often causing understeer where the front end doesn't turn as sharply as the driver intends. Some drivers describe it as the car feeling "loose" or "nervous" in corners.

Dirty air also affects cooling systems. Race cars rely on smooth airflow to cool their engines, brakes, and other components. Turbulent air reduces cooling efficiency, potentially forcing drivers to slow down to prevent overheating—even if they have the pace to push harder.

The biggest impact of dirty air is on overtaking. A driver might be faster than the car ahead, but getting close enough to attempt a pass means entering that turbulent wake. The resulting loss of grip and downforce makes it extremely difficult to stay close through corners, creating a frustrating catch-22 for racing drivers.

Interestingly, dirty air has an opposite effect on straightaways. When following directly behind another car in a straight line, a driver benefits from slipstreaming—the low-pressure zone that reduces air resistance and allows higher speeds. However, this advantage disappears in corners where dirty air dominates.

Race car designers constantly work to minimize dirty air's effects. The 2022 Formula 1 regulation changes, for example, specifically aimed to reduce turbulent wake and allow cars to follow more closely. Teams also adjust their car setups and drivers alter their racing lines to find cleaner air and maintain performance.