Permeable materials in homes act as sponges for harmful chemicals: study

Original Article ↗ Hacker News Discussion ↗

Study focus and open questions

  • Seen as a “brick in the wall” rather than directly actionable advice; it quantifies VOC sorption but doesn’t answer practical questions like:
    • How easily different compounds can be removed from surfaces.
    • How much is transferred via touch vs. re‑emitted to air.
  • Some note that materials storing and slowly releasing pollutants is worse than simple dilution: contaminants linger indoors instead of dissipating quickly.

Ventilation, filtration, and cleaning strategies

  • Common advice: bring in fresh air (open windows) and monitor CO₂, VOCs, and PM2.5; use filters when outdoor particulates are high.
  • Several emphasize that HEPA filters mainly remove particles; VOCs require activated carbon (ideally several pounds’ worth).
  • For HVAC: suggestions to use appropriate MERV 13–16 filters, not HEPA in returns (excess pressure drop, noise, possible blower damage).
  • DIY options: CR boxes (for particulates), window fans tied to CO₂ sensors, and custom vents with fine mesh against pollen.
  • Many recommend heat/energy recovery ventilators (HRV/ERV): bring in filtered outside air while conserving heat/humidity. Praised highly by those who retrofitted them, but noted as expensive, bulky, and hard to add in older or rented homes.
  • Quoted paper text stresses that ventilation alone doesn’t remove many surface‑bound contaminants; physical cleaning (vacuuming, mopping, dusting) is needed.

Air quality monitors: value and limitations

  • People report CO₂ monitors as eye‑opening for showing buildup in occupied rooms.
  • Concerns:
    • Many cheap CO₂ units are “fakes” using proxies and auto‑calibration that can systematically underestimate in poorly ventilated spaces.
    • True NDIR CO₂ sensors are relatively costly and often assume regular exposure to outdoor air for calibration.
    • VOC sensors in consumer gear are generally relative indicators, not precise absolute measurements.
  • Some share positive experiences with specific devices and DIY setups, emphasizing that even imperfect monitors are useful for trend awareness and automation.

Indoor vs outdoor air and energy/comfort tradeoffs

  • For many locations, outdoor air has worse PM or pollen than indoors; opening windows is not always beneficial.
  • Closed windows still appear to provide some protection from certain gaseous pollutants, for reasons commenters describe as not well understood.
  • Debate over costs and comfort:
    • Opening windows can substantially raise heating/cooling bills and sometimes overwhelms heating capacity.
    • Others counter that short “shock ventilation” and the low thermal mass of air make occasional airing inexpensive if the building mass stays warm.
    • Humidity, condensation, and mold risks at low indoor temperatures are discussed, with disagreement over how serious these are.

Smoke, odors, and material “sponges”

  • Strong agreement with the “sponge” metaphor:
    • Homes, garages, plastics, textiles, foam insulation, and electronics retain smells (smoke, gasoline, fabric softener) for years and re‑emit them when warmed.
  • Heavy indoor smoking or fire damage often requires extreme remediation:
    • Sometimes full removal of porous materials (drywall, insulation, plaster, etc.) is the only reliable fix.
    • Ozone treatments can help but have their own toxicity and material‑damage concerns.
  • Comparisons to smoker cars, old submarines, and retro hardware emphasize how persistent absorbed volatiles are.

Meta‑reactions

  • Some call the findings “obvious” (“permeable materials are permeable”) and see little news value.
  • Others argue that rigorous quantification matters for building codes, ventilation design, and public awareness, and that HN readers simply enjoy the technical detail.