Report on the Benzene Study of 2008-2009

Abstract

The purpose of this study was to determine whether reducing the amount of benzene in gasoline, which is scheduled to take place in 2011, will effect a change in indoor air benzene levels in Anchorage, Alaska. This is an interim report that discusses the first phase of a two-phase study. The first phase measured benzene levels in homes and garages every month for over one year. Due to the lack of chemical markets, the gasoline refined in Alaska contains 5% or more of benzene. Over the past two decades, volatile organic compounds (VOCs) measured in Anchorage, Alaska, have had higher concentrations in both indoor and ambient air than most other cities in the United States. Previous studies in Anchorage have shown that attached garages are a significant source of benzene and other VOCs in the living space of homes. In 2007-2008 we conducted a randomized study of houses with attached garages in Anchorage, Alaska, to determine whether there were associated respiratory health risks. We asked the resident owners of these houses to measure the benzene, toluene, ethyl benzene, and xylenes (BTEX) in their homes for one week using a passive vapor monitor badge. The results of that study showed that 47% of the houses had indoor-air benzene levels that—if they were maintained throughout the year—would exceed the minimal risk levels for inhalation set by the Agency for Toxic Substances and Disease Registry (ATSDR). Sixteen percent of the houses exceeded the acute risk. The results also showed that the BTEX measured in the indoor air came from gasoline fumes. We conducted this second study to determine whether levels found on a single, weekly measurement adequately represented the actual annual exposure in that house. We also wanted to see what the ratio was between levels in the garage and levels in the house since most of the exposure was thought to be coming into the house from the garage. We were also interested in any seasonal variation in the exposure to indoor benzene concentrations. This study would give us that sense of seasonal variability to be able to approximate long-term exposure and to guide future study. We were getting baseline data that could demonstrate the effect of the reduction in benzene in gasoline on the indoor air quality in Anchorage. It is expected that the level of benzene in gasoline will be reduced starting as soon as next year.