Particle number concentrations near the Rome-Ciampino city airport M. Stafoggia a, b, * , G. Cattani c , F. Forastiere a , A. Di Menno di Bucchianico c , A. Gaeta c , C. Ancona a a Department of Epidemiology, Lazio Region Health Service / ASL Roma 1, Via C. Colombo 112, 00147 Rome, Italy b Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden c Italian National Institute for Environmental Protection and Research, Via V. Brancati 48, 00144 Rome, Italy highlights  An extensive campaign of minute-specific PNC implemented in Ciampino Airport, Italy.  PNC increase by ~20,000 particles/cm 3 /minute in the 5 min after take-offs.  PNC increases are three times larger when prevalent wind from the airport runway.  Large resident population, with potential health impacts from airport-generated PNC. article info Article history: Received 25 March 2016 Received in revised form 23 September 2016 Accepted 26 September 2016 Available online 28 September 2016 Keywords: Airplane emissions Ultrafine particles Particle number concentrations Distributed-lag models Health effects abstract Human exposure to ultrafine particles (UFP) has been postulated to be associated with adverse health effects, and there is interest regarding possible measures to reduce primary emissions. One important source of UFP are airport activities, with aircraft take-offs being the most relevant one. We implemented two measurement campaigns of total particle number concentrations (PNC), a proxy for UFP, near a medium-size airport in central Italy. One-minute PNC averages were collected on June 2011 and January 2012 concurrently with 30-min average meteorological data on temperature and wind speed/direction. Data on minute-specific take-offs and landings were obtained by the airport authorities. We applied statistical regression models to relate PNC data to the presence of aircraft activities while adjusting for time trends and meteorology, and estimated the increases in PNC ±15 min before and after take-offs and landings. We repeated the analyses considering prevalent wind direction and by size of the aircraft. We estimated PNC increases of 5400 particles/cm 3 /minute during the 15 min before and after take-offs, with a peak of 19,000 particles/cm 3 /minute within 5 min after take-offs. Corresponding figures for landings were 1300 and 1000 particles, respectively. The highest PNC estimates were obtained when the pre- vailing wind came from the runway direction, and led to estimated PNC increases of 60,000 particles/ cm 3 /minute within 5 min after take-offs. No main differences were noted from the exhaust of different types of aircrafts. The area surrounding Ciampino airport is densely inhabited, raising concerns about the potential adverse effects of long-term and short-term exposure to airport-borne UFP. A close monitoring of airport activities and emissions is mandatory to reduce the public health impact of the airport on the nearby population. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Atmospheric pollution is one of the main environmental risk factors to human health (Lim et al., 2012). Long-term and short- term health effects from air pollution exposure have been widely documented all over the world, especially among populations living in densely populated urban areas. Epidemiological research during the last two decades has indicated that exposure to air pollution at the levels presently measured in European urban en- vironments is associated with an increase in mortality and with a variety of health conditions, including emergency room visits and hospital admissions for respiratory and cardiovascular diseases. Particulate matter (PM) is the air pollutant most consistently * Corresponding author. Department of Epidemiology of the Lazio Region Health Service / ASL Roma 1, Via C. Colombo 112, 00147 Rome, Italy. E-mail address: m.stafoggia@deplazio.it (M. Stafoggia). Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv http://dx.doi.org/10.1016/j.atmosenv.2016.09.062 1352-2310/© 2016 Elsevier Ltd. All rights reserved. Atmospheric Environment 147 (2016) 264e273