Odorous aldehyde emissions from a commonly used alkyd paint were measured and characterized. Initial formulation analysis indicated no measurable aldehydes in the liquid paint. However, small environmental chamber tests showed that, for each gram of the alkyd paint applied, more than 2 mg of aldehydes (mainly hexanal) were emitted during the curing (drying) period. The emission profiles of aldehydes were very different from those of other volatile organic compounds such as alkanes and aromatics. Since no measurable aldehydes were found in the original paint, it is suspected that the aldehydes emitted were produced by autoxidation of the unsaturated fatty acid esters in the alkyd resins. It was found that the hexanal emission rate can be simulated by a mathematical model assuming that the autoxidation process was controlled by a consecutive first-order reaction mechanism. The mathematical model was used to predict the indoor air hexanal concentrations for a typical application of the alkyd paint tested. The result indicated that the aldehyde emissions can result in prolonged (several days) exposure risk to occupants.

Units: SI