Evaporative emissions of 1,3-butadiene from petrol-fuelled motor vehicles

This study reports the identification and quantification of 1,3-butadiene in petrol and in the evaporative emissions from Australian light-duty passenger vehicles. The mass fraction of 1,3-butadiene in each of the different grades of any brand of Australian petrol was found to be relatively constant for a given marketing area. However, the mass fractions vary significantly between the different brands (or refineries) from 0.004±0.001% to 0.047±0.008%. The measurements of the evaporative emissions of 1,3-butadiene from in-service motor vehicles were performed using standard Australian Design Rule 37/00 (ADR 37/00) Sealed Housing Evaporative Determination (SHED) tests. For post-1985 catalyst equipped vehicles fuelled with unleaded petrol, average evaporative emissions of 1,3-butadiene were 9.4 (0.7–22) and 5.0 (0.1–23) mg per test for diurnal and hot soak SHED tests, respectively. The corresponding average evaporative emissions for the older, pre-1986 non-catalyst equipped vehicles fuelled with leaded petrol were 26.5 (11.7–45.4) and 9.2 (4.3–13.1) mg per test, respectively, about double the observed emissions from newer vehicles. For the complete vehicle set (all ages), the average mass fraction of 1,3-butadiene in the total hydrocarbon (sum of C1–C10 hydrocarbons) emission was 0.21±0.14% from the diurnal phase and was 0.11±0.06% from the hot-soak phase. Evaporative emissions were estimated to contribute about 4% (ranging from 1–15%) of the total (exhaust and evaporative) emissions of 1,3-butadiene from Australian motor vehicles.