[1] Univ Leeds, Sch Civil Engn, Aerobiol Res Grp, Leeds LS2 9JT, W Yorkshire, England
[2] Univ London Imperial Coll Sci Technol & Med, Dept Infect Dis, Wellcome Ctr Clin Trop Med, London, England
[3] Univ Bradford, Sch Engn Design & Technol, Med Engn Grp, Bradford BD7 1DP, W Yorkshire, England