Use the 24-hour PSI for the official health-advisory context and the one-hour PM2.
5 reading for recent particulate conditions. Consider duration, exertion, location and personal health rather than reacting to one number alone.
Understand the time windows
The 24-hour PSI smooths exposure over a day, while one-hour PM2.5 can move sharply. They answer related but different questions and should not be expected to match moment by moment. (NEA myENV)
Screenshots and social posts can be old, from another region or missing the timestamp. Open myENV and record location, metric and time.
| Situation | What changes |
|---|---|
| Planning the day | Start with the 24-hour PSI health advisory |
| Checking a recent change | Review the one-hour PM2.5 trend and local conditions |
| Sensitive person has symptoms | Reduce exposure and follow medical advice |
| Outdoor event is long or strenuous | Use a lower threshold for changing the plan |
Add the exposure dose
A short walk and a two-hour hard run create different inhaled exposure. Combine concentration with duration and exertion when choosing an alternative. (NEA air-pollution FAQs)
Children, older people and those with heart or lung conditions may need earlier adjustments. Follow the official advisory and the person healthcare plan.
Example: If one-hour PM2.5 rises while the 24-hour PSI remains lower, a sensitive runner can shorten or move the session indoors and continue monitoring rather than waiting for both metrics to align.
Build alternatives
Move exercise indoors, shorten the route, reduce intensity or reschedule. Check indoor ventilation and air cleaning rather than assuming every indoor setting is equivalent.
Breathing difficulty, chest pain or significant worsening needs medical attention. Air-quality numbers do not replace symptom-based care.
- Open myENV
- Record location and time
- Read 24-hour PSI
- Read one-hour PM2.5
- Assess duration and exertion
- Adjust for health risk
- Monitor symptoms and updates
