Total VOC Flux
VC-MET-214 — total volatile organic compound flux from the canopy — a broad chemical-activity and leak signal.
Definition
Total VOC Flux is the aggregate emission rate of volatile organic compounds from the canopy surface (µg·m⁻²·h⁻¹), measured by photoionization detectors on the PhytoSense Mesh. It is a broad-spectrum complement to single-species gas metrics.
Why it matters
Total VOC flux captures chemical activity that individual cells miss — solvent traces from a process leak, defensive volatiles under herbivory, or off-gassing from a containment fault. It is a wide net for 'something is happening' in a zone.
Formula
Φ_VOC = PID_response · k_cal − Φ_baseline
[µg · m⁻² · h⁻¹]
PID_response = photoionization current, zone mean
k_cal = isobutylene-referenced calibration factor
Φ_baseline = rolling 24 h zone floor
Speciation is not resolved; use ethylene (VC-MET-213) and
lab assay for identification.
Inputs
| Input | Detail | Source |
|---|---|---|
| PID array | Photoionization current, per node | PhytoSense Mesh |
| Calibration | Isobutylene reference factor | Lab |
| Baseline | Rolling 24 h zone floor | CHLORA |
Units & Scale
µg·m⁻²·h⁻¹, integer, zone mean with 24-hour baseline subtraction. Increasing-is-worse; upper thresholds only.
Sampling & Source
- Sampled every 10 minutes by the mesh PID array.
- Baseline floor recomputed on a rolling 24 h window.
- Unspeciated — pair with lab assay to identify drivers.
Thresholds
OK
WARN
CRIT
Recent Trend
Zone roll-up, last 14 sampling periods (current 180):
Interpretation Guidance
| Band | Reading | Likely Driver | Action |
|---|---|---|---|
| 50–300 | Background | Normal metabolism | None. |
| 301–600 | Elevated | Defensive volatiles or minor leak | Investigate; check VC-MET-213. |
| 601–1000 | WARN | Process leak or stress | Grab-sample; localize. |
| > 1000 | CRIT | Containment / solvent fault | Auto-escalate; ventilation review. |
Related Metrics
Ethylene Emission
Speciated stress marker.
VC-MET-406Airborne Spore Load
Air-quality sibling.
VC-MET-111Canopy Airflow Velocity
Dilution / transport.
VC-MET-408HEPA Filter Loading
Filtration state.
Related SOPs
- Air-quality investigation — SOP Library.
- Monitoring — Monitoring Systems.