Hygroscopicity of indoor aerosols and its influence on the deposition of inhaled radon decay products

Abstract

Consumer spray products, combustion products, and cooking aerosols are the significant sources of airborne particles to the indoor atmosphere. These particles serve as carriers of radon decay products to the lungs. When inhaled, some particles will extract water from the air at the high relative humidity (RH ∼99.5%) in the respiratory tract and grow in size. Since the deposition of particles in different compartments of the lungs, and hence the inhaled dose, depends on the size of the particles, it will be different for the particles that grow from those that do not. The study of the hygroscopic growth of these indoor aerosol particles was performed using a tandem differential mobility analyzer. Dry monodisperse particles of known initial size were selected by the first differential mobility analyzer (DMA) and then exposed to high RH (99-99.5%) in a growth chamber using a wetted water reactor. The size of these particles was measured by the second DMA. It was observed that some products do not grow at all, whereas others exhibit moderate to high growth. A comparative study of the deposition of the inhaled growing and non-growing particles, and its influence on the lung dosimetry, is presented.