Equipment and Techniques
The process of measuring is integral in the research of chemical and physical properties of particulate matter (PM) with their specification mass sizes, PM10 and PM2.5 (Arslan, Aybek & Ekerbcer, 2010; Perez, Rapp & Kunzli, 2010). Several methods can be offered to develop this process and achieve the required results. Methods for measuring PM fractions include filter paper samples, tapered element oscillating microbalance, also known as TEOM, impingers, and light scattering systems. Each method has its characteristics and peculiarities.
Sampling Techniques and Peculiarities
At the beginning of the 20th century, first attempts to monitor PM concentrations were observed. The main goal of that process was to measure the volume of dust fall. Several SSIs (size-selective inlets) based on impactors, cyclones, and dual filters were offered to investigate the particles and identify their aerodynamic size. Air sampling rates can be used to define the worth of substrates through their chemical analysis (Chow 1995).
Filtration remains to be the most frequently used method with the help of which it is possible to investigate the atmosphere and gather PM10/2.5 samples for analysis. The process of filtration is complicated, and it is necessary to pay attention to each step and the goal that has to be achieved. Air should be drawn through a filter with properly rated pumps in a certain period. Gravimetry is the measurement that has to be followed because it determines the volume of possible gathered material.
Reference methods are used to sample PM and analyze size fractions through different cascade impactor devices in a certain period (that is 24 hours). There is an almost real-time measurement that is preferred in long-term air quality networks. Some devices cannot be used for a long period and have to be measured. In this paper, attention is paid to the long-term properties of devices with the help of which the particles of various sizes can be measured and correlated. TEOM and beta gauge devices are examples that have to be evaluated.
Filter Paper Samples
Filter paper samples introduce a versatile approach to collect PM and hold air through a pump. Gravimetric analysis is a significant part of the process in terms of which it is possible to obtain the required mass measurements of all filters. It has to be developed as soon as a sampling period is ended because it aims to weight all filters before and after sampling and identify temperature and humidity that have to be appropriate for a particular environment. The minimization of particle volatilization is the result that has to be achieved when exposed filters are properly treated through filter paper sampling. Gravimetric methods of monitoring PM can be divided into two main groups.
The first group is the collection of reference methods in terms of which a sampler is used to draw particles through an inlet, separate them into 10 or 2.5, and collect in filters where a portion of analysis can be developed (SKC 2011). The second group includes equivalent methods in terms of which direct-reading instruments are used to separate total samples (0-10 μm) into fine and coarse fractions with the help of a virtual impactor.
TEOM
TEOM stands for the tapered element oscillating microbalance. This technique is used to measure air particle concentrations (Wang et al. 2009). Its principle of work includes the importance to suck air through an inlet and its head that can restrict the size of particles that have to enter the chosen device. As soon as all particles pass through the filter, their number can be increased due to the natural vibrations that occur in the device.
This type of vibration helps to obtain the required correlation between the filter mass and the frequency of vibrations. The main positive aspect of the work with such a device is the possibility to measure air every 15 minutes. Such frequency allows tracking pollution and analyzing it in real-time. In some TEOM constructions, there are sensor units to calculate oscillation frequency. During this process, a mass rate is divided by the flow rate.
Beta Gauge Monitor
Beta gauge monitoring works the same way other techniques usually work. Air is drawn, and particles are deposited on a filter. The intensity of beams helps to define particulate mass. This device is defined as a good alternative to TEOM that helps to save costs and achieve the same results for making conclusions.
Light Scattering System
Light scattering systems are based on the relation between light scattering and particle size. This method helps to obtain information about the number of particles that can be found in the chosen area of the atmosphere (Environment Agency 2006). There is a built-in pump that performs the main function of the device. The peculiarity of these systems is the possibility to be used as a portable device to investigate long- and short-term pollution spots.
Impingers
Impingers are the devices that draw air and direct it to a nozzle that is immersed in liquid. These devices are appropriate when it is necessary to capture an airborne contaminant and find an effective solution. The analysis of water helps to establish a matter. Besides, they can be used for personal monitoring (Todd 1998). The only disadvantage is their fragility and the inability to be used for multiple monitoring.
Reference List
Arslan, S, Aybek, A & Ekerbcer, HC 2010, ‘Measurement of personal PM10, PM2.5 and PM1 exposures in tractor and combine operations and evaluation of health disturbances of operators’, Journal of Agricultural Sciences, vol. 16, pp. 104-115. Web.
Chow, JC 1995, ‘Measurement method to determine compliance with ambient air quality standards for suspended particles’, Journal of Air Waste Management, vol. 45, pp. 320-382. Web.
Environment Agency 2012, Monitoring PM10 and PM2.5. Web.
Perez, N, Rapp, R & Kunzli, N 2010, ‘The year of the lung: outdoor air pollution and lung health’, The European Journal of Medical Sciences, vol. 140. Web.
Todd, LA 1998, ‘Evaluation of the work environment’, in JM Stellman (ed.), Encyclopedia of occupational health and safety, Clearance Center, Danvers, MA, pp. 30.14-30.22. Web.
Wang, C, George, C, James, E, James, E, Farnsworth, AH, Gregory, M, Olson, AS & Jugal, KA 2009, ‘A novel optical instrument for estimating size segregated aerosol mass concentration in real time, Aerosol Science Technology, vol. 43, pp. 939-950. Web.