Pollution personal samplers

Personal samplers are those for continuously monitoring exposure of persons to hazardous air-borne substances in the living and/or occupational environment. These samplers are often used in surveys to measure personal exposure to air pollutants and thus to calculate subjects doses from their respiration and living patterns. Personal samplers may be categorized as either active or passive. 

Once the inhalation exposure questions have been identified, the specifications for each personal monitor must be determined and the monitor must be validated for the contaminant being measured. Table I, updated from Samet et al. (14), identifies currently available personal monitors, and Table II, taken from an Environmental Protection Agency (EPA) report (15), shows the projected needs in the 1990s. There are a number of opportunities for research on personal monitors Table II indicates that relatively few commercial units are currently available for either particulate or gas-phase species. For compounds such as polycyclic aromatic hydrocarbons (PAHs), a two-stage sampler is required because some PAHs exist simultaneously in the gaseous and particulate phase (16). Consequently, research must be ranked with respect to the significance of the air pollution problem, and the technological developments required to provide reliable samplers must be defined. 

Each of these considerations must be resolved before a personal monitor can be applied to air pollution research and characterization studies. Some advances have been made for carbon monoxide, volatile organic compounds, acid aerosols, and particulate matter (PM-10 and RSP these represent the masses of all particles collected in samplers with 50% cut sizes of 10 and 25 xm, respectively) and its components (12, 22-31). Each advance is still undergoing development, and further advances can be anticipated for these as well as for other pollutants. The next generation of monitors will probably include devices for some pollutants that incorporate the use of microsensors. Currently, microsensors are being examined for detection of nitrogen dioxide and ozone, but the range of sensors available suggests that they can be used for a number of compounds (10, 32) ... 

Samplers for polar organic pollutants have been developed relatively recently compared with those for nonpolar organic compounds. Two main types are available the POCIS (Alvarez et al. 2004, Alvarez et al. 2007 and Chapter 2.2 in this book) and the Chemcatcher (Kingston, 2002). There has been an increased interest in monitoring polar compounds in recent years since the European Community has become aware of the presence of pharmaceuticals, components of personal care products and some... 

A few simple personal sampling systems are shown in Figure 1 for sampling SPM and gaseous and/or vapor components. The use of active samplers is described in the following sections according to the air pollutants. 

Techniques for unknown pollutants involve collecting a sample over a period of time and returning it to the laboratory for detail chemical analysis. Collection can be in containers such as bladders, bags, cylinders, bottles, syringes or on chemically absorbent materials such as activated charcoal or silica gel. Those methods which use containers may lose some of the collected gases or vapours by adherence to the inside of the container. The chemical absorbers are usually contained in small glass or metal tubes connected to a low-volmne sampling piunp and can be worn by a worker in a similar fashion to the personal dust samplers. 

Cumulative samplers can be used to greatest advantage in determination of spatial variations in pollutant concentration their low cost and small size relative to automated air monitoring devices makes it practical to deploy samplers at multiple locations simultaneously throughout a study area. Cumulative sampling is also the only feasible method currently available to make quantitative measurements of personal exposure to most air contaminants at typical ambient concentrations in the general urban environment. 

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