Freshly emitted aerosol from combustion sources is characterized by high levels of nucleation mode particles. Such particles have very low atmospheric lifetimes, due to their efficient coagulation and deposition processes. Thus, particle concentration rapidly decays both temporally and spatially from the emission point. Accordingly, also the relevant respiratory doses change. In proximity to the emission source, high short term peak exposures could occur. Then, the exposure estimate should rely on measurements of aerosol size number distribution able to track the rapid aerosol dynamic. To study the influence of the time resolution on such estimates, simultaneous measurements were carried out through Scanning Mobility Particle Sizer (SMPS) and Fast Mobility Particle Sizer (FMPS) spectrometers during particle generation events in both indoor (cooking activities) and outdoor (military aircraft exhausts) microenvironments. Such microenvironments were chosen because of the different aerosol dynamics after the generation: very slow deposition and diffusion for the indoor and very fast dilution in the outdoor. Aerosol size distributions were measured in the same diameter range (14-600 nm) with 135 s and 1 s time resolution for the SMPS and FMPS, respectively. Based on the two datasets, respiratory exposure estimates were carried out through the deposition model of International Commission on Radiological Protection. In the case of the military aircrafts, at a distance of 50 m, the spike values of respiratory doses evidenced by FMPS data were hardly described by SMPS data which is unable to follow the steep increases and decreases in particle doses.
Short term dose to ultrafine particles during indoor and outdoor generation events
BUONANNO, Giorgio;STABILE, Luca
2012-01-01
Abstract
Freshly emitted aerosol from combustion sources is characterized by high levels of nucleation mode particles. Such particles have very low atmospheric lifetimes, due to their efficient coagulation and deposition processes. Thus, particle concentration rapidly decays both temporally and spatially from the emission point. Accordingly, also the relevant respiratory doses change. In proximity to the emission source, high short term peak exposures could occur. Then, the exposure estimate should rely on measurements of aerosol size number distribution able to track the rapid aerosol dynamic. To study the influence of the time resolution on such estimates, simultaneous measurements were carried out through Scanning Mobility Particle Sizer (SMPS) and Fast Mobility Particle Sizer (FMPS) spectrometers during particle generation events in both indoor (cooking activities) and outdoor (military aircraft exhausts) microenvironments. Such microenvironments were chosen because of the different aerosol dynamics after the generation: very slow deposition and diffusion for the indoor and very fast dilution in the outdoor. Aerosol size distributions were measured in the same diameter range (14-600 nm) with 135 s and 1 s time resolution for the SMPS and FMPS, respectively. Based on the two datasets, respiratory exposure estimates were carried out through the deposition model of International Commission on Radiological Protection. In the case of the military aircrafts, at a distance of 50 m, the spike values of respiratory doses evidenced by FMPS data were hardly described by SMPS data which is unable to follow the steep increases and decreases in particle doses.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
