Aldehyde and Seek: Tracking R-CHO Production through the Ozonolysis of VOCs in Household Air Fresheners

In the fight against climate change, engineers and policymakers are turning to energy-efficient homes as a means of lowering greenhouse gas emissions. These new homes rely on improved insulation to reduce the amount of energy used for utilities. Corollary to this is a reduction in air exchange throughout the home, often leading to an accumulation of hazardous air pollutants. Washington State University's Laboratory for Atmospheric Research is undertaking a four-year EPA-funded research investigation analyzing indoor air quality as it pertains to climate change and human health. As part of this study, the chemical composition of commercial air fresheners was investigated. Products such as candles and aerosol sprays are known to emit volatile organic compounds (VOCs). This project first characterized the gases released by household air fresheners before analyzing their secondary products produced from ozonolysis reactions. During preliminary trials, off-gases from several air fresheners, including aerosol sprays and passive diffusers, were sampled for VOC content. Off-gases from aerosol sprays were diluted into 2 SLPM of nitrogen and off-gases from passive diffusers were diluted into 6 SLPM of blended nitrogen and zero air from a sampling chamber into a gas chromatograph – mass spectrometer (GC-MS). The chromatograms from the preliminary trials reveal the presence of hydrocarbon-based solvents, ozone-reactive monoterpenes such as limonene and alpha-pinene, and several known carcinogens, including toluene. Further analysis determined the mass emission rate of compounds of interest for each air freshener product. Researchers then used known ozonolysis pathways for several common monoterpenes to predict the formation of secondary aldehyde and ketone pollutants. The predicted abundance of these pollutants, notably formaldehyde, were used in a box model to estimate household concentrations. This information will be used later to analyze the presence of these chemicals in the homes used in the EPA study.