Long‐Term Diffusive Samplers for the Indoor Air Quality Evaluation

Abstract

Three kinds of diffusion samplers, conceived to perform long-term samplings in indoor sites are illustrated in this work. Two of them, in part deriving from the previous "Analyst for VOC" device, extend the field of application up to the semi-volatile organic compounds (SVOC), PAHs and nicotine in particular. A third device, which employs a basic barium hydroxide solution as an absorbing medium, is proposed for the determination of carbon dioxide levels which indicate the air change quality in the indoor sites. Laboratory and field experiments, performed in order to assess the reliability of the proposed devices, are shown. A monthly monitoring campaign, performed at three private apartments in Rome and its outskirts highlights that the indoor pollution levels are a complex function of various concurrent and opposite factors, like external air pollution, internal sources, air change rate and sink effect of surfaces, which contribute to depletion phenomena through adsorption and/or decomposition processes.

Indoor Air Quality. Volatile Organic Compounds: Sources, Sampling and Analysis

“…The diffusive sampling technique is known to be the cheapest and easiest way to perform extensive sampling campaigns, both in temporal and spatial terms. Moreover, this is the only collection technique allowing the true separation of the vapour phase species from the particle bound fraction (Bertoni et al, 2004;Namiesik et al, 2005). A lot of different models of passive sampler have been proposed by many researchers; in this chapter we can show only a "classic" sampler (Analyst, developed by the Italian National Research Council, IIA-CNR, Figg.…”

Long-term sampling: Suitable monitoring strategy for determination of semi-volatile PAHs at outdoor and indoor sites

“…This model reproduces the shape of "Analyst" (Marbaglass s.n.c., Rome Italy) [11] running with monoaromatics (h: 24 mm, i.d. : 20 mm, collecting layer film: 4 mm), however it is open on both sides and holds the adsorbent centrally; in that way, the uptake rate of the sampler is increased by a factor of 4 compared to "Analyst".…”

“…The virtual uptake rate of gases onto the adsorbing surface will be proportional to the molecular diffusion coefficient (D), which is specific to each compound, accordingly to the Fick's first law. Since at least one order of magnitude separates the D coefficients of molecules from those typical of fine particles, diffusion of the latter is usually unlikely to be accounted for [10,11,13].…”

SPME Sampling of BTEX before GC/MS Analysis: Examples of outdoor and indoor Air Quality Measurements in Public and Private Sites

“…A more significant comparison between passive tube sampling and SPME would necessitate several equally spaced SPME samplings during 24 hours for time averaging. Comparisons between indoor and outdoor data 18 lead to conclude that the indoor concentrations, as long as it concerns organic pollutants, are a result of various contributing events: internal emissions, which tend to increase concentrations; air renewal, which tends to make equal indoor and outdoor levels; a sink effect of surfaces, which tends to deplete at least the heaviest molecules. Several papers discuss the measurements of BTEX concentrations in indoor and outdoor air and, in most cases, it has been verified that indoor concentrations exceed outdoor ones.…”

“…19 It is particularly evident in flats where cigarette smokers are present. 18,20 For all the analytes, the outdoor concentration variability is due to its correlation with emission sources intensity and local microclimatic factors. The indoor/outdoor concentration ratio (in/out) reveals the relationship between outdoor and indoor sources.…”