Abstract
Exposure to ultrafine particles has been associated with short- and long-term effects on human health. The object of this paper was to assess Particle Number Concentration (PNC) and size distribution in a university environment and study the indoor/outdoor relationships. Measurements were carried out using co-located (indoor/outdoor) condensation particle counters and size spectrometers during two seasonal periods characterized by different meteorological conditions at five selected classrooms different for size, capacity, floor and use destination. PNC was dominated by particles in the ultrafine mode both indoor and outdoor. The indoor/outdoor ratios were on average between 1 and 1.2 in the summer and between 0.6 and 0.9 in the winter. Mostly the differences found among classrooms could be related to the condition of use (i.e., crowding, natural air exchange, air conditioning, seasonality). Only little differences were found among PNC measured immediately outside the classrooms. Based on information taken during the measurement campaigns, on the classrooms condition of use, it was possible to assess as a source of indoor particles in the coarse mode, the presence of students and teachers.
Highlights
The dimensional range below 0.1 μm is defined as ultrafine mode or Aitken nuclei (0.02 < Dp < 0.1 μm)
Particle Number Concentration (PNC) is reflected on indoor levels, in a context of real use of the environments
This work highlighted a seasonality of indoor levels linked to the different natural ventilation conditions of indoor environments in summer and winter
Summary
The dimensional range below 0.1 μm is defined as ultrafine mode or Aitken nuclei (0.02 < Dp < 0.1 μm). Particles in this size range are called ultrafine (UFP). They are numerically prevalent, compared to the total detectable in an air sample, they contribute little to the overall mass. Number Concentration (PNC) and on the size distribution of ultrafine particles. Exposure to ultrafine particles has been associated with short and long-term effects on human health [13]. The specific or differential toxicity of UFP with respect to particles of other fractions has not yet been established with certainty [13,14]
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