Dispersion of ultrafine particle pollution from an international airport: Characteristics and short- and long-term effects in surrounding areas

Airports have been identified as major sources of ultrafine particles, which have gained increasing attention due to their linkage with adverse health effects. To better understand the exposure, impacts and needed regulatory actions related to airport-originated pollution, the characteristics, dynamics and dispersion of these emissions should be known. In this study, we investigate particle pollution from a medium-large international airport (Helsinki-Vantaa, Finland) by utilising a stationary measurement site near the airport and mobile laboratory measurements up to 10 km away from the determined airport reference location. We report particle number concentration (PNC) and size distributions (1.2 nm-2.5 µm), emission factors as well as dispersion of particles larger than 2.5 nm, 4 nm, 10 nm and 23 nm, BC, PM_2.5 and lung deposited surface area (LDSA^al). Furthermore, data from a long-term air quality monitoring site and 12 PNC sensor sites up to 15 km away are used to investigate the long-term impacts of the airport. Finally, we estimate the airport's contribution to yearly averaged PNC and LDSA^al in the surrounding areas. Overall, the studied airport is a major source of ultrafine particles: The downwind PNC_{> 10 nm} exceeded the World Health Organization's definition for high short-term PNC (20 000 #/cm³) up to a 4.4 km distance, and 500-5 000 #/cm³ yearly increases of PNC_{>10 nm} at 2-5 km distances were estimated. The high contribution of particles smaller than 10 nm and nanocluster aerosols (<3 nm) suggest an important role of (semi-)volatile compounds in the airport emissions.