Exposure and emission evaluations of methyl ethyl ketoxime (MEKO) in alkydpaints

Small environmental chamber tests were conducted to characterize the emissi ons of a toxic chemical compound methyl ethyl ketoxime (MEKO) - from three different alkyd paints. It was found that MEKO emissions occurred almost im mediately after each alkyd paint was applied to a pine board. Due to the fa st emission pattern, more than 90% of the MEKO emitted was released within 10 hours after painting. The peak concentrations of MEKO in chamber air cor related well with the MEKO content in the paint. Material balance showed th at good recovery (more than 68%) was achieved between the MEKO applied with the paint and the MEKO emitted. The chamber data were simulated by a first order decay emission model assuming the MEKO emissions were mostly gas-pha se mass transfer controlled. The model was used to predict indoor MEKO conc entrations during and after painting in a test house. It was found that the predicted lest house MEKO concentrations during and after the Fainting exc eeded a suggested indoor exposure limit of 0.1 mg/m(3) for all three paints . The predicted MEKO concentrations exceeded even the lower limit of a sugg ested sensory irritation range of 4 to 18 mg/m(3) with two of the three pai nts tested. The model was also used to evaluate and demonstrate the effecti veness of risk reduction options including selection of lower MEKO paints a nd higher ventilation during painting.