Detailed industrial hygiene characterizations were made of two molded flexible toluene-diisocyanate (584849) (TDI) foam manufacturing factories (factory-A and factory-B) and one flexible slab foam manufacturing factory (factory-C). All three factories used an 80:20 mixture of 2,4-toluene-diisocyanate (584849) (2,4- isomer) and 2,6-toluene-diisocyanate (91087) (2,6-isomer). Employees at factory-A and factory-B involved with foam production cleaned molds, sprayed release agents and monitored processes prior to hot or cold curing processes. Other employees repaired and finished the products prior to packaging. NIOSH Method-326 half shift air sampling was conducted at all the sites to determine monomeric TDI concentrations. The NIOSH recommended 10 hour time weighted average for both isomers is not in excess of 35 micrograms per cubic meter. Results indicated that factory-A cold curing workers were exposed to geometric mean air concentrations of TDI twice that of workers involved with the hot cure process in which molds are enclosed in exhausted ovens. Hot cure workers in factory- A versus the other two factories revealed less difference in TDI exposure between pouring line workers and finishers. At factory-B pouring line workers experienced the highest exposures. Of the finishing workers, only those who used a hot iron brazing tool (associated with thermal degradation processes) experienced elevated personal exposures. Pouring line workers at factory-C had regular and low exposure, but finishers using hot wire cutting tools experienced increased TDI concentrations compared to other finishers. Except for factory-C's pouring line area, the 2,6-isomer was more prevalent than the 2,4-isomer in each department. The author stresses the need for proper facility engineering and adequate fresh makeup air.