Research Projects

This study investigated the chemical composition and emission factors of selected particulate matter (PM) sources in the Lake Tahoe basin. PM is of interest because particles either by themselves or acting as nutrients or attachment points for algae are obscuring water clarity in the lake. Particulate matter (PM) samples directly relevant to major PM sources in Lake Tahoe were collected and analyzed as part of this study. Sources sampled included residential wood combustion, motor vehicle exhaust, and entrainment of road dust, traction control material, and road deicing material. Measurements of road dust emission factors with the TRAKER vehicle consistently showed ~20%-30% higher PM emission factors in California than in Nevada. Differences in road maintenance practices based on jurisdiction may account for the variation in emission factors. Road dust emission factors from South Lake Tahoe, CA and Incline Village, NV were nearly equivalent. The largest emission factors were observed at the entrances to subdivisions and neighborhoods. All measured emissions data from this study were compared with the CARB Tahoe Air Basin emission inventory scaled to the entire basin. The CARB emission estimates derived from the EMFAC model were 2 to 10 times greater than the measured on-road exhaust emissions based on estimated fuel consumption. Paved road dust, residential wood combustion, and campfire emissions were in general agreement with the CARB estimates. For particulate matter, the combined emission inventory indicates that residential wood combustion, unpaved road dust, and paved road dust are the largest sources.