Hello all, Some of our chaps use a substance which contains Polymethylene Polyphenyl Isocyanate (expanding foam). We were recently informed by our COSHH assessors that they now recommend that users wear a AXP3 mask.

However, our supplier has told us that this mask will not protect the users from the fumes?? And in fact there is no mask manufactured that can protect the users from these fumes.

They are using for approx 1/2 hour per shift.

What do other people use please?

Thanks

Carrie,

Some processes with chemicals containing isocyanates use positive pressure air respirators which ensure the operators are always breathing fresh air, probably a better option than face masks.

One of the problems is operators taking masks off in their work area where the ventilation is poor and isocyanate fumes are still lingering.

Also if you don't have good local ventilation are you protecting other employees nearby?

I expect you know that isocyanate vapour if inhaled can cause occupational asthma and also sensitisation. For this reason all your operators should be included in a surveillance programme.

The programme includes surveillance for asthma as well as dermatitis.

For asthma, operators should have annual lung function testing and answer a questionnaire. For new employees carry this out on beginning work; after 6 weeks; 6 months and then yearly.
Also there should be a programme of urine sampling which checks the effectiveness of your RPE or LEV controls. Carry it out during the first few months of someone’s employment to show that RPE or LEV working practices are providing enough protection. You are likely to need to do it at appropriate intervals after that unless it is clear from results that exposure is not happening.

For more info see

http://www.hse.gov.uk/co...isocyanates-spraying.htm

and

http://www.coshh-essenti....uk/assets/live/G402.pdf

and

http://www.hse.gov.uk/pubns/guidance/g408.pdf

leadbelly,

That's right, HSE recommend POSITIVE pressure, constant flow air-fed breathing apparatus for isocyanate spraying vapour mist conditions - see links above.

Carrie's process, though, is not a spray process, I think it's like a foam injection process which does release vapour but not as a mist like paint. An LEV could be adequate for her process, so that is another option she may consider particularly as it then protects other employees working nearby.