An orange air quality alert means the Air Quality Index (AQI) is between 101 and 150, a level the EPA officially classifies as “unhealthy for sensitive groups.” At this level, most healthy adults won’t notice symptoms, but certain people, particularly those with heart or lung conditions, older adults, and children, can experience real health effects from spending time outdoors.
What the AQI Scale Looks Like
The AQI runs from 0 to 500 and uses a color-coded system to make air quality easy to read at a glance. Orange sits in the middle of the scale, one step above yellow (moderate, 51 to 100) and one step below red (unhealthy for everyone, 151 to 200). In the yellow range, air quality is acceptable with only minor concern for people who are unusually sensitive to pollution. Once the index crosses into red territory, everyone can begin to feel the effects.
Orange is the threshold where air pollution starts to matter for daily planning. The general public is unlikely to be affected at this level, but it’s no longer a “business as usual” day for a significant portion of the population.
Who Counts as a “Sensitive Group”
The EPA defines several specific groups as sensitive to orange-level air quality:
- People with heart or lung disease, including asthma, COPD, and coronary artery disease
- Older adults (generally 65 and older)
- Children under 18
- People with diabetes
- People with lower socioeconomic status, a category the EPA includes because factors like income, education, housing quality, and occupation all influence how much pollution someone is exposed to and how well they can recover from it
That last group surprises many people, but it reflects real-world data. Someone who works outdoors, lives near a highway, or has limited access to healthcare faces a compounding set of risks that makes even moderate pollution levels more dangerous. The sensitive groups list is broader than most people assume. If you add up children, older adults, and anyone with asthma, diabetes, or heart disease, it covers a large share of the population.
What Happens in Your Body at This Level
Orange alerts are most commonly triggered by fine particulate matter (PM2.5), tiny particles small enough to pass deep into your lungs and even enter your bloodstream. At AQI levels of 101 to 150, the concentration of these particles in the air is between 35.5 and 55.4 micrograms per cubic meter.
For someone with healthy lungs, this concentration typically isn’t enough to cause noticeable symptoms. But for someone with asthma, it can trigger airway inflammation, tightness, and increased use of a rescue inhaler. For someone with heart disease, the particles can worsen cardiovascular strain. The effects also get worse the longer you’re exposed and the harder you’re breathing, which is why exercise outdoors is the main concern. Deep, rapid breathing pulls more pollutants into the lungs with each breath.
What You Should Actually Do
The core advice during an orange alert is to reduce prolonged or heavy exertion outdoors, especially if you fall into one of the sensitive groups. Johns Hopkins Medicine puts a practical number on it: limit outdoor time to 30 minutes or less when possible. That doesn’t mean you can’t step outside or walk to your car. It means this isn’t the day for a long run, an outdoor soccer practice, or hours of yard work.
Some practical steps:
- Move workouts indoors. A gym, a home workout, or even a mall walk avoids the combination of heavy breathing and polluted air.
- Avoid high-traffic areas. If you do go outside, stay away from busy roads where vehicle exhaust concentrates pollution beyond the ambient level.
- Keep windows closed. Running your HVAC system with a clean filter is more effective at keeping particle levels down indoors than open windows, even if the outdoor air doesn’t look hazy.
- Check the forecast before planning. AQI levels shift throughout the day. Mornings often have different readings than afternoons, so timing outdoor activities around lower-pollution hours can help.
If you’re a parent, this is especially relevant for kids’ outdoor activities. Children breathe faster relative to their body size, spend more time running around, and their lungs are still developing. Schools and sports leagues in areas with frequent orange alerts sometimes adjust recess and practice schedules on high-AQI days.
How Orange Differs From Red
The key distinction is who’s affected. At orange (101 to 150), the health guidance targets sensitive groups while the general public can go about their day normally. Once the AQI hits 151 and enters the red zone, everyone may begin to experience health effects, and members of sensitive groups face more serious risks. At red, healthy adults and children are advised to limit prolonged outdoor exertion, not just sensitive populations.
Orange alerts are common in many U.S. cities, particularly during summer heat, wildfire season, or periods of stagnant air. They don’t indicate an emergency, but they are a signal to pay attention, especially if you or someone in your household has a respiratory or cardiovascular condition. The EPA retained the same AQI breakpoints for the orange category in its most recent 2024 review, keeping the 101 to 150 range and its associated health messaging unchanged.