®With a test report in hand, confirm first which standard it uses — the two common standards differ in both sampling conditions and limits, and using the wrong one can lead to a very different conclusion.
The two common standards
- GB/T 18883 (Indoor Air Quality Standard): oriented to "living environments", usually sampling after windows have been closed for a longer period, closer to everyday living conditions and stricter overall;
- GB 50325 (Code for Indoor Environmental Pollution Control of Civil Building Engineering): oriented to "project acceptance", with a shorter closing period before sampling and looser requirements, commonly used at handover.
Key limits for reference
Below is an approximate comparison of common limits (always refer to the latest official standard text, which is updated over time):
| Indicator | GB/T 18883 | GB 50325 (Class I) | Notes |
|---|---|---|---|
| Formaldehyde | ≤ 0.08 mg/m³ | ≤ 0.07 mg/m³ | Core indicator of engineered board emissions |
| TVOC | ≤ 0.60 mg/m³ | ≤ 0.45 mg/m³ | Total of many organic compounds |
| Benzene | ≤ 0.03 mg/m³ | ≤ 0.06 mg/m³ | From paints and adhesives |
| PM2.5 | ≤ 0.05 mg/m³ | — | Particles, reduced by purifiers |
| Carbon dioxide | ≤ 0.10% (1000 ppm) | — | Shows whether ventilation is sufficient |
| Radon | ≤ 300 Bq/m³ | ≤ 150 Bq/m³ | From soil and building materials |
How to read a report
- Check the sampling conditions: how long windows were closed and where the sampling points were placed;
- Check the test method and metrological qualification, so a "reading from a handheld device" is not misread as a result;
- Check each individual verdict: if any key indicator exceeds the limit, the space does not yet meet the standard;
- For occupancy decisions, refer to GB/T 18883 first — it is closer to real living conditions.
The same flat tested under 18883 is often stricter than under 50325. When deciding "is it safe to move in", look at the 18883 result first.