Aerosol Science 37 (2006) 1442 – 1454 www.elsevier.com/locate/jaerosci A passive sampler for airborne coarse particles Naomichi Yamamoto a , ∗, 1 , Masaji Hikono b , Hiromi Koyama b , Kazukiyo Kumagai a , Minoru Fujii c , Yukio Yanagisawa a a Department of Environmental System, Institute of Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa-shi, Chiba 277-8563, Japan b Sibata Scientific Technology Ltd., Nakane 1-1-62, Soka-shi, Saitama 340-0005, Japan c National Institute for Environmental Studies, Onogawa 16-2, Tsukuba-shi, Ibaraki 305-8506, Japan Received 16 February 2006; received in revised form 2 May 2006; accepted 4 May 2006 Abstract The personal aeroallergen sampler (PAAS) with a structure resembling a gimbal to enable a particle collection surface contin- uously directed upward regardless of inclination of the sampler was developed. To evaluate the particle size-dependent collection characteristics by the PAAS, the particle size distributions obtained by the PAAS were compared with those by an existing reference active sampler for sampling durations of 5 h to 6 days. The results showed good correlations between the two methods, suggesting usability of the PAAS for long-term personal monitoring of airborne coarse particles such as aeroallergens. The effective particle deposition velocities experimentally obtained for the personal samplings by the PAAS were 0.17, 0.35, 0.66 and 1.6 cm s -1 for particles with projected area diameters of 10–20, 20–30, 30–50 and 50–100 m, respectively. Unlike existing active samplers, the PAAS is convenient for personal air sampling because of simplicity of handling. It can be easily used for epidemiological studies to investigate relationships between aeroallergen exposures and allergic airway diseases.  2006 Elsevier Ltd. All rights reserved. Keywords: Personal aeroallergen sampler (PAAS); Line-sensing optical microscope; Deposition model; Passive sampler; Gimbal 1. Introduction The passive samplers are devices to collect airborne substances by naturally occurred mass transfers. The passive samplers are convenient for personal air monitoring, and have been widely used because of simplicity of handling (e.g., Levy, Lee, Spengler, &Yanagisawa, 1998; Shields & Weschler, 1987; Shinohara et al., 2004;Yanagisawa & Nishimura, 1982). While the passive sampling methods have been established for gaseous substances such as nitrogen oxides or volatile organic compounds, the methods are still under development for airborne particles. This is primarily due to complexity to convert the amounts passively collected to the concentrations in air. Since ambient aerosol particles are generally heterogeneous in terms of size, shape and density, it is difficult to determine contributions of each particle transport mechanism including the Brownian diffusion, gravitational settling, and inertial or electrostatic depositions. ∗ Corresponding author. Tel.: +81 463 93 1121x4336; fax: +81 463 90 2074. E-mail address: yamanao@is.icc.u-tokai.ac.jp (N. Yamamoto). 1 Present address: Department of Nursing, School of Health Sciences, Tokai University, Bohseidai, Isehara-shi, Kanagawa 259-1193, Japan. 0021-8502/$ - see front matter  2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jaerosci.2006.05.002