Quick Summary
Category: Unhealthy
Color Code: Red
One-Line Description: At AQI 151, air quality is considered unhealthy for everyone, marking the beginning of the "Unhealthy" range.
Location on Scale: First value in the Unhealthy category (150-200), just above the "Unhealthy for Sensitive Groups" threshold
What Does AQI 151 Mean?
AQI 151 represents a significant threshold in air quality measurements where the air becomes unhealthy for the general population, not just sensitive groups. At this level, there's enough pollution in the air that everyone might begin to experience some adverse health effects.
This level often occurs during forest fire events, severe industrial pollution, or intense traffic combined with weather conditions that trap pollutants near the ground. The jump from AQI 150 to 151 is particularly significant because it crosses into a new health action category where public health officials typically begin issuing broader warnings.
Health Implications
General Population
Healthy adults may experience difficulty breathing and throat irritation
Physical exertion becomes noticeably more difficult
Potential for mild chest pain during deep breathing
Possible development of coughing or wheezing
Sensitive Groups
Children may experience pronounced shortness of breath
Elderly individuals should avoid any outdoor activity
Asthma sufferers might need to increase medication usage
Heart disease patients should monitor symptoms carefully
Recommended Actions
Outdoor Activities
Cancel or postpone strenuous outdoor athletic events
Limit outdoor exercise to light or moderate activity under 30 minutes
Move team sports practices indoors
Outdoor workers should wear appropriate masks and take frequent breaks
Indoor Precautions
Keep windows and doors closed
Run air purifiers on high setting
Check and replace HVAC filters
Create a clean air room if possible
When Do We Usually See AQI 151?
During summer wildfire season in western regions
Winter temperature inversions in valley locations
Rush hour in major cities during stagnant air conditions
Industrial areas during unfavorable weather patterns
Comparison with Other AQI Levels
Compared to AQI 141: Significantly more severe health implications; broader population affected
Compared to AQI 161: Slightly less severe, but similar precautions needed
Protective Measures
Essential Steps
Check local air quality alerts and forecasts multiple times daily
Wear N95 mask for essential outdoor activities
Reduce outdoor exposure time to absolute minimum
Keep rescue medications readily available
Recommended Equipment
N95 or KN95 masks (surgical masks insufficient)
HEPA air purifiers rated for room size
Air quality monitor for indoor spaces
Weather-stripping for doors and windows
Common Questions About AQI 151
Is it safe to exercise outside at AQI 151?
No, it's not recommended to exercise outdoors at AQI 151. Any strenuous activity should be moved indoors to a filtered air environment. If you must exercise outdoors, limit it to gentle walking for no more than 15-20 minutes.
How long can I stay outside at AQI 151?
Healthy adults should limit outdoor exposure to 1-2 hours maximum. Sensitive individuals should remain indoors as much as possible. Essential outdoor activities should be done with proper protection (N95 mask).
What should I do if AQI reaches 151?
Check local health department advisories
Close all windows and doors
Turn on air purifiers
Cancel outdoor activities
Monitor symptoms of vulnerable family members
Technical Details
PM2.5 Range: 55.5-150.4 µg/m³
PM10 Range: 255-354 µg/m³
Ozone Levels: 0.125-0.164 ppm
Other Pollutants: SO₂: 186-304 ppb, NO₂: 361-649 ppb
Additional Resources
[Local Air Quality Management District]
[Emergency Services: 911]
[Poison Control: 1-800-222-1222]
Historical Context
Frequently seen during California wildfire seasons
Common in Beijing's winter months
Occasionally reached during severe dust storms in Phoenix
Typical during intense pollution events in developing industrial cities
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