Drawing on data from more than 108,000 recorded activities across over 100 countries, the report highlights a major blind spot. While athletes increasingly track training load, sleep, and recovery, the quality of the air they breathe during exercise is rarely considered, despite its direct physiological impact.

The Hidden Load Athletes Carry

Air pollution exposure is amplified during physical activity. Ventilation rates can increase five to six times during running, meaning a session undertaken in “moderate” pollution can result in a disproportionately high inhaled dose. Air Aware Labs’ data shows that a runner training on a busy urban road can inhale three to five times more pollution than someone running on a nearby backstreet.

Traffic-related pollutants such as nitrogen dioxide (NO₂) are particularly problematic, reducing exercise efficiency, impairing tolerance, and increasing respiratory strain. Ozone (O₃), meanwhile, is linked to reduced aerobic capacity, especially during warmer conditions when air pollution and heat stress combine. These effects challenge the assumption that performance outcomes are driven solely by fitness, effort, or recovery behaviours.

Air Quality and Recovery Signals

One of the report’s most important findings is the emerging link between air quality and heart rate variability (HRV) — a key indicator of recovery and autonomic nervous system balance. Air Aware Labs observed that cleaner air is associated with higher daily HRV, while elevated pollution correlates with suppressed recovery.

Although this analysis is still at an early stage, the relationship was statistically significant and detected despite a small sample size. The implications are substantial. Many wearables currently interpret environmental stress as behavioural failure, labelling users as under-recovered or overtrained, when air pollution may be a hidden driver. Integrating personalised exposure data could lead to more accurate readiness scores and better-informed training decisions.

From Awareness to Action

Encouragingly, the 2025 data shows that athletes do act when information is presented clearly. Runners choosing quieter routes, cyclists moving sessions into parks, and athletes training indoors on high-pollution days achieved exposure reductions of 20–50%, often with minimal impact on performance.

The key lesson is simple: when air quality data is personalised, calm, and relevant, it becomes a practical performance tool rather than background noise.

Redefining Performance Intelligence

Air Aware Labs’ conclusion is unambiguous. Personal air exposure is not an externality, it is a core variable shaping performance and recovery. As environmental intelligence becomes measurable and actionable, the future of sport science may depend not only on how athletes train, but on the air they breathe while doing it.