Inventory and emission factors of creosote, polycyclic aromatic hydrocarbons (PAH), and phenols from railroad ties treated with creosote

Inventory, emission factors, and total yearly emissions of creosote, PAH, and phenols from the Swiss railway network were determined based on the analysis of cross sections of selected railroad ties which were in use for up to 46 years. Approximately 9 million wooden railroad ties are installed in Switzerland, each being treated with roughly 15 kg of creosote. During the service time of a typical railroad tie of 20-30 years, about 5 kg of creosote are emitted, corresponding to an emission factor of 208 mg/(m(2) x day). PAH emissions occur as emissions of the volatile 2- and 3-ring PAH (such as naphthalene, acenaphthylene, acenaphthene, anthracene, fluorene, phenanthrene; boiling point up to 340 degreesC). PAH emissions for an average railroad tie were found to be about 0.5 kg (sum of 16 EPA-PAH), corresponding to an emission factor of 20.3 mg/(m(2) x day). Emissions of phenolic compounds were determined to be in the range of 10 g for each tie, corresponding to an emission factor of 0.58 mg/(m(2) x day). According to our study, about 1710 t of creosote components are being emitted by the ties of the Swiss railway network, every year. Based on the Values reported above, yearly emissions of 2- and bring EPA-PAH add up to 139 t Cumulated emissions of phenolic compounds are in the order of 4 t per year.