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Comparison of primary National Ambient Air Quality Standards for SO2, odor detection, and health effects.
| STANDARD | EPA | NIOSH |
|---|---|---|
| 15 min | – | 5000 ppb |
| 1 hr | 75 ppb | – |
| 10 hr | – | 2000 ppb |
Notes: Odor detection threshold: 330–5000 ppb (2700 ppb avg). Health effects: non-asthmatic (>2000 ppb): asthmatic (≥400–500 ppb).
