Smog and Cycling — When It's Better to Stay Home
A cyclist inhales 2–5 times more air than a pedestrian. During exercise you breathe deeper and faster, and pollutants get further into your lungs. This article uses Poland's air-quality monitoring as its reference, where smog is a real problem — especially in winter, during the heating season.
Air-quality thresholds — when not to ride?
| Air quality index | PM2.5 (µg/m³) | Recommendation for cyclists |
|---|---|---|
| Very good | 0–13 | Ride freely |
| Good | 13–35 | Ride normally |
| Moderate | 35–55 | Limit intensity — ride easy |
| Fair | 55–75 | Short commutes are OK, outdoor training not advised |
| Poor | 75–110 | Stay home. Use the trainer. |
| Very poor | >110 | No outdoor exercise, full stop |
PM2.5 is the most dangerous indicator — particles under 2.5 micrometres in diameter reach the lung alveoli and the bloodstream. PM10 is less dangerous, but still harmful.
Why is a cyclist more exposed?
- Higher minute ventilation — during exercise you inhale 40–60 litres of air per minute vs 6–8 l/min at rest
- Mouth breathing — the nose filters out some particles, but during exercise you breathe through your mouth, bypassing that filter
- Proximity to traffic — a cyclist rides at the height of car exhaust pipes
Health effects
Short-term: coughing, irritation of the throat and eyes, a drop in performance (10–15% in poor air quality). Long-term with regular exposure: chronic respiratory disease, cardiovascular disease, reduced lung capacity.
How to check air quality?
- Apps — Airly, GIOŚ (Poland's national air-quality service, powietrze.gios.gov.pl), Kanarek, IQAir
- Local sensors — many Polish cities have a network of Airly sensors with real-time readings
- A rule of thumb — if you see haze or fog with low humidity and a temperature below 5°C, it's probably smog
Strategies for the heating season
- Time of day — smog is worst in the morning (6–9) and evening (17–22). Midday (11–14) is usually best — the sun warms the air and lifts the inversion layer.
- Route — ride further from main roads, through parks and green spaces. Concentrations near busy streets are 2–3× higher than just 200 m away.
- The trainer — training at home when air quality is poor isn't a compromise, it's common sense.
- Anti-smog masks — they filter out some particles, but make breathing harder during exercise and aren't comfortable for longer rides. Better than nothing, but not a real solution.
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