Test protocol · version 1.0
Laser fume (PM2.5) protocol
We run a standard engraving job in a closed room and log PM2.5 once per second at 1 m from the machine, before, during and after the job. We report the rise over background, the peak, and how long the air takes to clear.
- Version
- 1.0 (September 25, 2026)
- Applies to
- diode lasers, galvo lasers, CO2 lasers, fiber lasers, fume extractors, enclosures
- Results so far
- None. Testing starts with our first purchased machines.
What we measure
| Measurement | Unit | Better | Notes |
|---|---|---|---|
| Mean PM2.5 rise over baseline during a 10-minute job | µg/m³ | Lower | Main number. |
| Peak PM2.5 (10-second average) | µg/m³ | Lower | Short spikes you would breathe standing next to the machine. |
| Clear-down time | minutes | Lower | Time for PM2.5 to return to within 10% of baseline after the job. |
Why this test
Burning wood, leather and acrylic releases smoke with fine particles. Many small sellers run lasers in spare rooms and garages.
Fume extractor and enclosure makers quote airflow (CFM) and filter stages, not what ends up in the room. This protocol measures the room.
Equipment
We list instrument classes and specifications rather than brands, because the exact units are still being purchased. Each result page will name the exact model and serial-level calibration date.
| Item | Minimum spec | Why |
|---|---|---|
| Two optical PM2.5 monitors | Laser-scattering particle sensors with ≥ 1 Hz logging, factory-calibrated; side-by-side agreement checked before each session | Two units catch a drifting sensor. Optical sensors are not reference instruments; see limitations. |
| Tripod mounts | 1.0 m from the machine’s front edge, sensor inlet at 1.2 m height | Roughly where a seated or standing operator breathes. |
| Test room | Closed room of measured volume (target 25–35 m³), HVAC and fans off, door closed, sealed window duct port | Makes runs comparable. Volume is published so you can scale to your room. |
| Anemometer | Vane type, 0.3–30 m/s | Checks extractor duct airflow against the rated figure. |
| Thermo-hygrometer | ±0.5 °C, ±3% RH | Humidity affects optical particle readings. |
Setup
- Ventilate the room, then close it and let PM2.5 settle to a stable baseline (10 minutes with < 2 µg/m³ drift).
- Configure the machine as it ships: built-in fan, exhaust hose routed out of the window port if one is supplied.
- For fume extractors: a reference laser (the same one every time) exhausts into the extractor under test, which recirculates into the room as a buyer would use it.
- For enclosures: the reference laser runs inside the enclosure under test; sensors sit outside it at 1 m.
Procedure
- Log 10 minutes of baseline.
- Run the standard job for 10 minutes: repeat KP-ENG-01 on 3 mm basswood plywood.
- Stop the job and keep logging until PM2.5 returns to within 10% of baseline, or 60 minutes, whichever comes first.
- Air the room fully; repeat the whole sequence three times on separate days.
- Optional material series (published separately): leather and cast acrylic.
Controls
- Same reference laser and same job for every extractor and enclosure tested.
- Same room, same sensor positions (marked on the floor).
- Runs with baseline above 25 µg/m³ are postponed.
- Humidity kept below 70% RH; optical sensors over-read in humid air.
Scoring
The fume sub-score (0–10) compares like with like: lasers with lasers, extractors with extractors.
| Component | Weight | Based on |
|---|---|---|
| Mean rise during job | 50% | µg/m³ over baseline |
| Peak (10 s) | 30% | µg/m³ |
| Clear-down time | 20% | minutes |
| Total | 100% |
Formula. Each component scores 10 × (best value in the group ÷ this value), capped at 10. Weighted sum, one decimal.
Scores are a convenience. The raw measurements are always published next to them, and our picks explain which measurement mattered for which kind of seller.
What we publish
- The full 1-second log from both sensors for every run (CSV), plus baseline and room conditions.
- Room volume, window-port size and duct routing photos.
- Measured duct airflow next to the manufacturer’s rated airflow.
Limitations
- Low-cost optical sensors are useful for comparing machines in the same room but are not reference-grade monitors, and their accuracy depends on the type of smoke. We compare, we do not certify.
- PM2.5 is not the whole story: laser fumes also contain gases (VOCs and others) that this v1.0 protocol does not measure.
- Nothing on this site is a health or safety assessment. WHO and EPA guideline values are shown only as context, not as a pass mark.
Where results will appear
On every product page this protocol applies to, a lab slot like the one below stays empty until we have measured that machine:
pm25_1mMean PM2.5 rise over baseline during a 10-minute job
Measurement pendingWe'll measure this on a unit we buy ourselves and publish the raw data. Read the protocol for Mean PM2.5 rise over baseline during a 10-minute job
Protocol changelog
When we change a protocol, we bump its version, explain why here, and re-run or flag any results measured under the old version.
| Version | Date | Change |
|---|---|---|
| v1.0 | September 25, 2026 | First public version, published before any machine was tested so readers can critique the method first. Not yet run on any machine. |
Other protocols
Sources
Every spec and number on this page links back to where it came from.