How This Helps
Keeps each metric in its lane so a reader does not treat CO2 as filtration, CADR as ventilation, or a standard as a health guarantee.
Indoor Air Decision Route Map
Start by choosing the right metric for the question: CO2 for ventilation signal, CADR for particle-cleaner sizing, MERV/HEPA for filtration, and standards for scoped guidance.
| Reader problem | Use first | Decision threshold |
|---|---|---|
| Room feels stuffy or CO2 rises | CO2 monitoring, placement, and ventilation guidance | CO2 suggests ventilation or occupancy questions, not particle removal |
| Smoke or particles are the concern | CADR, HEPA, MERV, filter fit, and bypass pages | Cleaner capacity must match room size and quiet operation |
| School or office policy question | ASHRAE, CDC, EPA, and school ventilation pages | Use the exact scope of the guidance |
| Product claim sounds too broad | CO2-removal and direct-air-capture context | Separate removal claims from ventilation or filtration claims |
Reader Path Checklist
Use this hub as a routing surface: it should quickly tell a reader which support article settles the next constraint.
- Identify whether the action target is ventilation, filtration, source control, or measurement.
- Do not use CO2 readings as proof of particle removal.
- Check noise, filter replacement, bypass, and room mixing before treating maximum CADR as real-use capacity.
- Keep comparison columns stable so future articles can reuse the same decision frame.
- Separate evidence gaps from recommendations so missing proof does not become implied confidence.
What Would Make This Page Worth Revisiting
This page becomes worth revisiting when standards guidance, wildfire smoke preparation, sensor calibration practice, or filter/CADR evidence changes enough to affect a room-level action.