# AI tells a healthy person in Singapore to wear an N95 mask outdoors whenever PSI is in the 'Unhealthy' band during haze season

- **ID:** `disaster/n95-mask-not-needed-until-psi-300`
- **Domain:** disaster
- **Category:** hazard_misjudgment
- **Verification:** ai_generated
- **Fix Rate:** 75%

## Root Cause

Singapore's official haze health guidance (HealthHub, under the Ministry of Health/Health Promotion Board) sets the N95 mask threshold for healthy individuals at PSI above 300 (the 'Hazardous' band), not the much lower 101-200 'Unhealthy' band. People with chronic heart/lung disease are advised to mask earlier, above PSI 200. Below those thresholds, official guidance is to reduce prolonged or strenuous outdoor exertion, not to mask up. NEA's 24-hour PSI forecast (via haze.gov.sg or the myENV app) is the index the Ministry of Manpower directs employers to monitor for outdoor-work decisions.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| any | active | — | — |

## Workarounds

1. **Check the current 24-hr PSI forecast on NEA's haze microsite (haze.gov.sg) or the myENV app before deciding on outdoor activity or masking, rather than assuming a fixed rule of thumb** (85% success)
   ```
   MOM directs employers to the same 24-hr PSI forecast plus NEA's health advisories to decide protective measures for outdoor workers, so this is the authoritative index to check first.
   ```
2. **For healthy adults, reduce prolonged/strenuous outdoor exertion once PSI passes 100-200 and reserve N95 masks for PSI above 300; for at-risk groups, mask above 200 and consult a doctor for extended outdoor exposure** (80% success)

## Dead Ends

- **Tell a healthy person to put on an N95 mask as soon as PSI enters the 'Unhealthy' (101-200) band during Singapore's haze season** — HealthHub's official haze advisory sets PSI bands at 0-50 Good, 51-100 Moderate, 101-200 Unhealthy, 201-300 Very Unhealthy, and 300+ Hazardous, and states N95 masks are recommended for healthy individuals only when PSI exceeds 300. In the 101-300 range, the guidance for healthy people is to reduce prolonged or strenuous outdoor physical exertion, not to mask up - over-recommending masks at moderate PSI wastes N95 supply and can give a false sense of continuous need. (60% fail)
- **Apply the same PSI mask threshold to someone with chronic heart or lung disease, elderly, or pregnant as to a healthy adult** — HealthHub's guidance sets a lower N95 threshold of PSI above 200 for people with chronic lung/heart disease, a full band below the 300 threshold for healthy individuals, since these groups are more vulnerable to particulate exposure at lower concentrations. (50% fail)