Field study of a soft X-ray aerosol neutralizer combined with electrostatic classifiers for nanoparticles size distribution measurements

Most conventional aerosol neutralizers are based on radioactive sources which are controlled by strict regulations restricting their handling, transport and storage. The TSI 3087 soft-X ray (SXR) neutralizer circumvents these legal restrictions. The aim of the present work is to compare the performances of the SXR as a standalone aerosol neutralizer with those of the conventional radioactive aerosol neutralizers 85Kr (TSI 3077) and 241Am (Grimm 5522) by performing field campaigns in a real environmental scenario. Results obtained with the SXR neutralizer, connected to a mobility particle sizer spectrometer (MPS) different from the device suggested by the manufacturer, were comparable with those obtained through radioactive aerosol neutralizers. Indeed, by changing the neutralizer the particle number concentration, measured with the MPS connected to the SXR neutralizer, laid almost within 10% uncertainty in the particle size interval 10-300 nm provided that the diffusion losses inside the SXR tube are considered. Based on this intercomparison, the SXR neutralizer can be regarded as a standalone instrument and could solve the problems associated with legal restrictions on radioactive neutralizers, and the need for a portable instrument for different measurement campaigns