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Toolbox Talks

Spray foam: isocyanates and the people nearby

Hazard communication 5 min 29 CFR 1926.55 · 29 CFR 1926.59 · 29 CFR 1926.57 · 29 CFR 1926.103

Drywall, HVAC, Roofing

Why it matters

Spray foam insulation is made by mixing chemicals at the gun. One side contains isocyanates, which can cause asthma. Once a worker becomes sensitized, even a tiny amount later can set off an attack. The sprayer is not the only one at risk. So is everyone breathing the same air.

The talk

Picture a spray crew foaming the walls of a new house while the electrician is still finishing a room down the hall. The mist from the gun drifts. The sprayer has a full-face, supplied-air mask on. The electrician has nothing. A few weeks later he starts wheezing at night and doesn't know why. That is how isocyanate sensitization often shows up. It can also come from skin contact, from cleaning the gun bare-handed, or from walking back into the room too soon. Once it starts, it may never go away, and the worker may not be able to be around foam again.

OSHA sets a ceiling limit for MDI, a common isocyanate in foam, and that limit is never supposed to be passed, even for a moment. The company has to have the safety data sheets, label the drums, and train you on what is in them. Ventilation has to keep the air below the limit, and the exhaust should go outside, away from other workers and air intakes. Respirators must be the right type and fit you under the company's program. For spraying indoors, that usually means more than a dust mask. Read the SDS and the maker's instructions for how long people stay out after spraying.

Here is how we run a foam job. Spray only when other trades are out of the area, and mark the area with signs and tape. Set up exhaust fans before you start. Wear the respirator, chemical goggles or full face piece, gloves, and coveralls the SDS calls for. Keep skin covered. Clean the gun and spills with gloves on. Keep everyone out until the re-entry time has passed. Spray in the lift thickness the maker allows, since thick passes can get hot enough to burn. If anyone starts coughing, wheezing, or gets a tight chest, get them out to fresh air and report it.

Key points

  1. One side of spray foam contains isocyanates that can cause asthma.
  2. After sensitization, even a tiny exposure can trigger an attack.
  3. MDI has a ceiling limit that must never be passed.
  4. Read the SDS and labels, and get trained on the chemicals.
  5. Exhaust the air outside and away from other workers.
  6. Keep other trades out during spraying and until re-entry time passes.
  7. Wear the respirator, eye, skin, and body protection the SDS calls for.

Do this

  • Clear and mark the area before spraying.
  • Set up exhaust fans before the first pass.
  • Keep skin covered and wear chemical-resistant gloves.
  • Follow the maker's re-entry time.
  • Report coughing, wheezing, or a tight chest right away.

Do not do this

  • Do not spray with other trades working nearby.
  • Do not touch foam chemicals or clean the gun bare-handed.
  • Do not go back in before the re-entry time.
  • Do not spray thicker passes than the maker allows.
  • Do not use a dust mask in place of the respirator the job calls for.

Talk about it

  1. When will we spray, and how do we keep the other trades out?
  2. What respirator does the SDS for this foam call for?

This is a short crew briefing. It does not replace a competent person, training, or the law.

Training aid only. This talk is not legal advice. It does not replace your company's safety program, a competent person, the equipment maker's instructions, or the OSHA standard itself.

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