1 2 3 4 Sources of Submicrometre Particles 5 Near a Major International Airport 6 7 8 1,2 1† 9 Mauro Masiol , Roy M. Harrison , 1 1 10 Tuan V. Vu , David C.S. Beddows 11 12 1 13 Division of Environmental Health and Risk Management, 14 School of Geography, Earth and Environmental Sciences 15 University of Birmingham 16 Edgbaston, Birmingham B15 2TT 17 United Kingdom 18 2 19 Division of Epidemiology, Department of Public Health 20 Sciences, University of Rochester Medical Center, 21 265 Crittenden Boulevard, CU 420644 22 Rochester, NY 14642, United States 23 24 25 26 27 28 29 30 To whom correspondence should be addressed. Tele: +44 121 414 3494; Fax: +44 121 414 3709; Email:
[email protected] †Also at: Department of Environmental Sciences / Center of Excellence in Environmental Studies, King Abdulaziz University, PO Box 80203, Jeddah, 21589, Saudi Arabia 1 31 ABSTRACT 32 The international airport of Heathrow is a major source of nitrogen oxides, but its contribution to 33 the levels of submicrometre particles is unknown, and is the objective of this study. Two sampling 34 campaigns were carried out during warm and cold seasons at a site close to the airfield (1.2 km). 35 Size spectra were largely dominated by ultrafine particles: nucleation particles (<30 nm) were found 36 to be ~10 times higher than those commonly measured in urban background environments of 37 London. Five clusters and 6 factors were identified by applying k-means cluster analysis and 38 positive matrix factorization (PMF) respectively to particle number size distributions; their 39 interpretation was based on their modal structures, wind directionality, diurnal patterns, road and 40 airport traffic volumes and on the relationship with weather and other air pollutants.