An environmental chamber and modeling study was conducted to reduce uncertainties in atmospheric ozone impacts for volatile organic compounds (VOCs) emitted from coatings. Some coatings VOCs (Texanol® and low-aromatic petroleum distillates) have near-zero or negative incremental ozone reactivities in chamber experiments, but calculations show positive ozone impacts in the atmosphere. Modeling indicated that experiments with increased light intensity and added H2O2 should give reactivities that better correlate with those in the atmosphere. After upgrading our chamber’s light source, experiments to test the new method performed as expected, and gave good correlations between experimental and atmospheric MIR values for the VOCs tested. These experiments also appear to be more sensitive to effects of VOCs on secondary organic aerosol (SOA) formation than previous experiments. Such experiments should be included in future environmental chamber reactivity studies, though other types of experiments are also needed for adequate mechanism evaluation.
Experiments were also conducted to assess ozone impacts of ethyl methyl ketone oxime (EMKO), and soy ester solvents. The EMKO results indicated it has both radical sinks and NOx sources in its mechanism, and has no measurable impact on SOA formation. The EMKO mechanism that simulated the data gave a negative MIR of -1.27 gm O3 /gm VOC, but positive MOIR and EBIR values of 0.41 and 1.14, respectively. This has implications about the use of the MIR scale for such compounds. The experiments to assess soy ester reactivity were not successful because of the low volatility of the constituents, but uncertainties concerning atmospheric availability are probably more important.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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