Aldehydes in passenger vehicles: An analysis of data from the RIOPA Study 1999-2001

Introduction: In-vehicle air quality (IVAQ) is a rising concern due to urban sprawl throughout the U.S. and the increased amount of time spent by individuals commuting in cars, etc. Few studies have considered in-vehicle toxic air contaminants; none collected data across multiple climate zones. Methods: Quantitative and qualitative field data were collected from participating non-smoking adults in communities located in Los Angeles County, California, Elizabeth, New Jersey and Houston, Texas. A baseline questionnaire was used to outline subject's general behaviors and an activity questionnaire summarized specific activities within the 48-hour sampling period. Statistics were conducted in Excel and in SAS (Cary, NC). Results: A significant difference (p< 0.001) in formaldehyde levels in cars was observed among study locations with median concentrations of formaldehyde in CA about twice as high in both NJ and TX. The highest concentration of acetaldehyde was observed in TX, and was over two orders of magnitude higher than the overall study median. Positive correlations were found between average relative humidity in CA and NJ and formaldehyde and acetaldehyde concentrations. The time car windows were closed was inversely correlated with formaldehyde across locations, and in CA and TX for acetaldehyde. Average wind speed and varying sky conditions also showed relationships to formaldehyde and acetaldehyde measurements. Conclusions: IVAQ during commuting may vary based on human behavior and meteorological factors. Additional studies are needed to further characterize ways to improve IVAQ. Understanding these factors may especially help people with respiratory illness to minimize potential exposure by altering driving habits.