Is It Safe to Train Outside Today?
AQI thresholds, heat, UV, and storms — a practical guide to deciding whether outdoor training is safe right now.
Quick Answer
AQI below 50 is ideal for all outdoor exercise. Between 51–100, most healthy adults are fine but sensitive individuals should reduce intensity. Above 100, consider shorter or lighter sessions. Above 150, move your workout indoors. The Training Conditions Score combines AQI with temperature, UV, wind, rain, and humidity into a single number — but the AQI thresholds below remain the most health-critical factor.
This is general guidance, not medical advice. Consult a healthcare provider if you have respiratory or cardiovascular conditions.
AQI Thresholds for Exercise
The table below shows exercise recommendations for each AQI level. These are based on EPA guidelines adapted for active individuals who breathe 10–20x more air during exercise.
All outdoor exercise is fine. Ideal conditions for long runs, intervals, and hard efforts.
Most healthy adults can exercise normally. Sensitive individuals (asthma, heart conditions) should watch for symptoms.
Reduce prolonged outdoor exertion. Shorten runs, lower intensity, or split workouts. Everyone may notice effects during hard efforts.
Move workouts indoors or significantly reduce duration and intensity. Avoid interval training and races.
Avoid all outdoor exercise. Use a treadmill or indoor bike instead.
Stay indoors. Avoid all physical exertion outdoors. Consider limiting even indoor exercise if building ventilation is poor.
PM2.5 vs. Overall AQI: Which Matters More?
The overall AQI is the highest sub-index of all measured pollutants. For runners, PM2.5 deserves special attention because these fine particles penetrate deep into your lungs and bloodstream — exactly where you don't want them during heavy breathing.
If the overall AQI reads 80 (Moderate) but PM2.5 alone is 95, treat it as if the AQI is 95 for exercise purposes. PM2.5 is the pollutant most directly linked to short-term respiratory effects during exercise.
Tip: Aeriqo shows the dominant pollutant alongside the AQI so you always know what's driving the number.
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Try Aeriqo FreeWhy AQI Varies Along Your Route
A city AQI of 60 doesn't mean your entire route is 60. Air quality can drop significantly near busy intersections and improve in parks just 200 meters away. Traffic corridors, construction zones, and elevation changes all create micro-variation.
This is exactly why route-level AQI matters for runners. A 10km route might pass through AQI 45 in a park, spike to 90 along a main road, and settle back to 55 by the river. Knowing the segments lets you adjust — or choose a different route entirely.
When to Move Your Workout Indoors
If the AQI is above 150, move indoors — full stop. Between 100–150, consider your personal sensitivity, the duration of your workout, and the intensity level.
Quick Rules
- • Above 150: Always move indoors
- • 100–150: Shorten duration, lower intensity, or go indoors
- • Check the forecast: if AQI will drop in a few hours, consider rescheduling
- • After intense exercise in poor air, watch for symptoms for the next 24 hours
Beyond AQI: Other Conditions That Make Training Unsafe
While the air quality thresholds above get the most attention — and rightly so, since the health risks are severe — your Training Conditions Score also flags other dangerous conditions:
Extreme Heat
Heat index above 40°C / 104°F is dangerous for outdoor exercise regardless of AQI. The score drops sharply when temperature and humidity combine to impair the body's cooling.
High UV Index
UV index above 8 means significant skin damage risk during prolonged outdoor exercise. The score accounts for this, but sunscreen and timing also matter.
Thunderstorms & Heavy Rain
Active precipitation makes outdoor training impractical and potentially dangerous (lightning, slippery surfaces). The score drops to reflect this.
The Training Conditions Score weighs all these factors together — a score below 20 means conditions are unsafe regardless of the specific cause.
Frequently Asked Questions
Is 120 AQI safe for running?
At AQI 120, sensitive groups should avoid prolonged outdoor exertion. Healthy adults can do shorter, lighter workouts but should skip intervals and long runs. If you notice any chest tightness or unusual shortness of breath, move indoors.
What AQI is too high for outdoor exercise?
Above 150 (Unhealthy), avoid outdoor exercise entirely. Between 100–150, reduce intensity and duration. Below 100, most healthy adults can exercise normally, though sensitive individuals should be cautious above 50.
Is 150 AQI bad for running?
Yes. At AQI 150, the EPA classifies conditions as Unhealthy for everyone. During exercise, you breathe 10–20x more air, multiplying your pollution intake. Move your workout indoors or reschedule.
Can I run if AQI is 80?
Yes, AQI 80 falls in the Moderate range and is generally fine for healthy adults. Keep your effort moderate if you're sensitive to pollution, and consider checking which pollutant is dominant — PM2.5 deserves more caution than ozone at this level.
Does AQI change along a running route?
Absolutely. AQI can vary significantly within a few hundred meters. Running through a park might expose you to AQI 40, while a nearby busy intersection could be AQI 90+. Route-level tools like Aeriqo show these variations segment by segment.
Should I wear a mask when running in moderate AQI?
Most runners find masks impractical during exercise because they restrict airflow. At moderate AQI (51–100), a mask isn't necessary for healthy adults. Above 100, it's better to move indoors than to run with a mask, as most masks don't seal well during heavy breathing.
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Complete AQI Guide for Runners
Deep dive into pollutants, thresholds, and how air quality can affect running performance.
Best Time to Exercise for Air Quality
Daily and seasonal AQI patterns to help schedule outdoor exercise.
WHO Guidelines vs. Safe-to-Run Thresholds
How WHO long-term limits differ from real-time AQI thresholds — and how to use both when planning outdoor exercise.
Training Conditions Score Explained
How the score combines AQI, temperature, UV, wind, rain, and humidity into a single training-readiness number.