While ozone repairs itself naturally, it’s a different story for heavily exposed workers.
From a front-page NYTimes story on workers sickened by poor ventilation in furniture factories:
… Businesses found nPB appealing partly because the E.P.A. had given it an endorsement of sorts by adding it to a list of chemicals that do not harm the ozone layer. But an unintended effect of that action was to allow sellers of the chemical to market it as federally approved, “nonhazardous,” green and worker-friendly.
As the chemical’s popularity grew, E.P.A. officials worried about its use in spray glues, especially in cushion-making factories where the agency had determined that even with “state of the art” ventilation, “nPB-based adhesives cannot be reliably used in a manner that protects human health.”
Environmental officials figured that OSHA, pressured by the Bush administration and Republican lawmakers to be more business-friendly, would not be capable of policing the growing threat. “OSHA is tough,” E.P.A. officials said, according to notes from a November 2006 meeting on concerns about nPB. “But their budget is small, and they are not going to crack down on small businesses.”
OSHA has never set a standard establishing safety limits on workers’ exposure to nPB. The E.P.A. recommended such a limit and considered banning the nPB glues, but it has yet to finalize the plan. It determined that most cushion companies using the glue had fewer than 100 employees, which meant they were less able to absorb the cost of another regulation.
“There just wasn’t the political will,” an E.P.A. official who was part of the decision-making said on the condition of anonymity… [Emphasis added]
Good point, I was thinking about the solvent when mentioning the gases, but they’re talking about the actual glue.
Ben,
Spray glue is not a gas. It is a high-molecular-weight polymer that would be easily trapped even by a simple cloth filter — even if it were dispersed to a molecular level. But spray guns do not provide enough energy to break it down to monomolecular particles, and even sub-micrometre particles are hard to make.
The solvent used to fluidize the glue for spraying can be more difficult to capture (and most solvents other than water represent a health hazard), but I don’t know of any that can’t be taken care of by a properly-sized sorption respirator. You can tell how good such respirators are if you care to wear one for 10-15 minutes. You will be overwhelmed with the richness and intensity of scents, many of which you didn’t know existed. Because the filter cuts them all out, the automatic gain control in your olfactory circuit maxes out on sensitivity trying to discern any signals, and when you take the filter off, it gets hit real hard by the concentrations so low you don’t normally detect them. A sorption filter formulated for volatile organic compounds can give you a rejection ratio of 3-4 orders of magnitude.
But, I understand, this report is about the binder component of the glue, not the solvent. If it really does any harm, I would suspect skin/eye contact (also preventable), rather than inhalation (presuming no sane person will use it without a respirator).
BTW, in the MSDS you linked, there is one toxic compound — acetonitrile — but from the analysis (<2%w/w) I can tell it is a manufacturing residue that is difficult to remove from the matrix, so it is not normally released to the environment until the matrix is decomposed in some way.
Spay masks don’t help with gases and fumes. Even full cartridge respirators are useless against a number of different gases. However, I’m skeptical about the claims of damage. What evidence is there that nPB is harmful in the first place?
MSDS’s on the matter are decidedly non-alarming
http://www.blairrubber.com/msds/Normac%20N-PrBr.pdf
Did they bother wearing spray masks?
Ozone repairs itself naturally, and workers self-replicate. One of these is more important than the other, the decision has been made on high.