Assessment of isocyanate exposure during the spray application of polyurethane foam.

This survey examined the air concentrations of diphenylmethane 4,4' diisocyanate (MDI) produced during the spray application of polyurethane foam at both indoor and outdoor locations. The sprayer, his helper(s), and fixed distances from the spray operation were sampled. The sprayers had the highest exposure levels, followed by outdoor helpers, then by indoor helpers. Area sample results showed that levels at a distance greater than 3 m (10 ft) outdoors and 8 m (25 ft) indoors were negligible, thereby supporting the establishment of a "work zone" around the spray operation.