title: Health effects caused by primary fine particulate matter (PM2.5) emitted from buses in the Helsinki metropolitan area, Finland.
abstract: Fine particle (PM(2.5)) emissions from traffic have been associated with premature mortality. The current work compares PM(2.5)-induced mortality in alternative public bus transportation strategies as being considered by the Helsinki Metropolitan Area Council, Finland. The current bus fleet and transportation volume is compared to four alternative hypothetical bus fleet strategies for the year 2020: (1) the current bus fleet for 2020 traffic volume, (2) modern diesel buses without particle traps, (3) diesel buses with particle traps, and (4) buses using natural gas engines. The average population PM(2.5) exposure level attributable to the bus emissions was determined for the 1996-1997 situation using PM(2.5) exposure measurements including elemental composition from the EXPOLIS-Helsinki study and similar element-based source apportionment of ambient PM(2.5) concentrations observed in the ULTRA study. Average population exposure to particles originating from the bus traffic in the year 2020 is assumed to be proportional to the bus emissions in each strategy. Associated mortality was calculated using dose-response relationships from two large cohort studies on PM(2.5) mortality from the United States. Estimated number of deaths per year (90% confidence intervals in parenthesis) associated with primary PM(2.5) emissions from buses in Helsinki Metropolitan Area in 2020 were 18 (0-55), 9 (0-27), 4 (0-14), and 3 (0-8) for the strategies 1-4, respectively. The relative differences in the associated mortalities for the alternative strategies are substantial, but the number of deaths in the lowest alternative, the gas buses, is only marginally lower than what would be achieved by diesel engines equipped with particle trap technology. The dose-response relationship and the emission factors were identified as the main sources of uncertainty in the model.
authors.affiliation: Centre of Excellence for Environmental Health Risk Analysis, National Public Health Institute, Finland.
authors.forename: Marko
authors.initials: M
authors.lastname: Tainio
authors.forename: Jouni T
authors.initials: JT
authors.lastname: Tuomisto
authors.forename: Otto
authors.initials: O
authors.lastname: Hänninen
authors.forename: Päivi
authors.initials: P
authors.lastname: Aarnio
authors.forename: Kimmo J
authors.initials: KJ
authors.lastname: Koistinen
authors.forename: Matti J
authors.initials: MJ
authors.lastname: Jantunen
authors.forename: Juha
authors.initials: J
authors.lastname: Pekkanen
mesh_terms: D000393:Air Pollutants; D000397:Air Pollution; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005387:Finland; D005579:Fossil Fuels; D005742:Gasoline / Q000009:adverse effects*; D006262:Health; D006801:Humans; D008962:Models, Theoretical; D009026:Mortality; D018986:Motor Vehicles; D010316:Particle Size; D018570:Risk Assessment; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D005579:Fossil Fuels; D005742:Gasoline; D001335:Vehicle Emissions