Transformations of Aerosol Particles from an Outdoor to Indoor Environment

Abstract

Aerosol particle size and chemical composition during summer and winter were investigated in this study. An automated switching valve allowed for indoor and outdoor environments to be sampled near-simultaneously with the same high temporal-resolution instrumentation. During the study, no known indoor sources were present and the sampled room was unoccupied throughout.Accumulation mode indoor/outdoor (I/O) ratios were substantially lower in winter than in summer. This reduction was attributed to particles of outdoor origin shrinking as they entered the warmer and drier indoor environment. An essential factor in this process appeared to be the difference (gradient) between the temperature and relative humidity of the indoor and outdoor environments during the winter. Online aerosol mass spectrometer measurements recorded a 34-38% decrease in I/O ratios for all nonrefractory species during the winter relative to the summer. A similar change in I/O ratios for all species indicated that physical, rather than chemical, processes were responsible.To assess the relative influence of various physical factors on I/O relationships, Spearman rank statistical tests were carried out. These identified wind speed to be negatively correlated to the indoor concentrations for all species. Wind roses incorporating I/O ratios were applied and showed that the wind speed and direction influenced the changes in the indoor composition. The relative outdoor concentration of different aerosol species, steepness of the I/O temperature gradient, and wind speed variability are concluded to be essential factors in I/O aerosol transformations.

Markers of Oxidative Stress in the Exhaled Breath Condensate of Workers Handling Nanocomposites

“…A Berner low-pressure impactor (BLPI, HAUKE GmbH, Gmunden, Austria) [ 25 , 26 ] was used to sample aerosol particles onto 10 stages corresponding to their aerodynamic diameter, covering the 25 nm–13.6 µm size range. The impactor samples were analyzed gravimetrically on an M5P balance (Sartorius GmbH, Goettingen, Germany, 1 µg resolution), followed by ion chromatography (IC) in a Dionex 5000 (Dionex Co., Sunnyvale, CA, USA), whose two-channel system enabled parallel determination of water soluble ions (both anions and cations) as described by Talbot et al [ 27 ]. The impactors were placed about 3 m from the individual processes at a height of approximately 1.5 m.…”

DNA Methylation Profiles in a Group of Workers Occupationally Exposed to Nanoparticles

“…Data from both SMPS and APS sizers were used to obtain more details related to size distribution and concentration of PM from the nanoscale range 6 nm up to 20 µm. More details related to exposure monitoring methods were published previously [20,49].…”

Cooking and electronic cigarettes leading to large differences between indoor and outdoor particle composition and concentration measured by aerosol mass spectrometry

“…50,[52][53][54]60,61 Recently, an online high-resolution mass spectrometric technique has also been used for this purpose in indoor environments without any active indoor sources. 55,62,63 Indoor to outdoor ratios (I/O) of the penetrated particle mass to indoor environments in winter ranged between 0.5-0.7 for organics, 0.3-0.5 for ammonium, 0.2 for nitrate, 0.5-0.6 for sulfate, and 0.6-0.9 for BC throughout the studies. 55,63 Positive matrix factorization (PMF) was applied to the penetrated organic particle mass in a multi-use, mechanically ventilated university building.…”