CARB Phase 2 refers to the California Air Resources Board's regulation limiting formaldehyde emissions from composite wood products. It's the strictest formaldehyde standard in the United States and has become a de facto national standard.
CARB Phase 2 sets emission limits for:
- Hardwood plywood: 0.05 ppm
- Particleboard: 0.09 ppm
- Medium-density fiberboard (MDF): 0.11 ppm (thin) / 0.13 ppm (regular)
Why it matters:
- Formaldehyde is a known carcinogen
- Composite wood products are major sources of indoor formaldehyde
- The standard applies to all composite wood products sold in California (and practically nationwide)
Beyond CARB Phase 2, look for:
- NAF (No Added Formaldehyde): Uses adhesives without formaldehyde
- ULEF (Ultra Low Emitting Formaldehyde): Even stricter than CARB Phase 2
For the best indoor air quality, solid wood remains preferable to composite wood products, but CARB Phase 2 compliance is an important baseline when composite wood is used.