Closed-cell foam is non-porous and doesn't absorb odors. Open-cell foam has slight porosity but is closed-cell adjacent in real-world performance. Smell concerns usually trace to the brief curing period (24-48 hours), not long-term.
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Closed-cell foam has densely packed cells with sealed walls, so no air or odor molecules can permeate the material. It does not absorb cooking odors, pet odors, smoke, or volatile organic compounds. Open-cell foam has interconnected cell structure (similar to a sponge in microstructure) and theoretically can absorb minor amounts of airborne molecules, but in real-world Cincinnati installs the absorption is negligible compared to other surfaces (drywall, carpet, fabric). Persistent post-install odor concerns almost always trace to one of three causes: (1) off-ratio mix during spray (rare with credentialed installers using calibrated equipment), (2) inadequate ventilation during cure, allowing the curing reaction's amine catalyst byproducts to linger, (3) spray applied in temperatures below 40°F or onto wet substrate, both of which can produce persistent fishy or chemical odor. Properly installed foam at 24 hours post-cure has no detectable odor. Cincinnati post-install odor-troubleshooting context: the rare "fishy" or persistent chemical odor reported by homeowners weeks after install almost always traces to one of three causes: off-ratio mix during spray (rare with credentialed installers using calibrated equipment), spray applied to wet substrate, or spray applied below 40°F substrate temperature. Remediation involves identifying the affected area and either removing-and-respraying or applying a sealing topcoat depending on severity.