Exposure to ultrafine particles and respiratory hospitalisations in five European cities

Evangelia Samoli, Zorana Jovanovic Andersen, Klea Katsouyanni, Frauke Hennig, Thomas A J Kuhlbusch, Tom Bellander, Giorgio Cattani, Josef Cyrys, Francesco Forastiere, Bénédicte Jacquemin, Markku Kulmala, Timo Lanki, Steffen Loft, Andreas Massling, Aurelio Tobias, Massimo Stafoggia, UF&HEALTH Study group