5 Mechanisms of Particle Deposition &Identify -Integrated Air Sampling

Questions: 1. Identify and describe the five primary mechanisms of particle deposition and then identify and describe the two primary methods of integrated air sampling for particulates used in industrial hygiene.2. Identify and describe at least four of the critical factors used in determining acceptable exposure levels to particulate materials.3. Identify and discuss the five critical exposure factors regarding gases. vapors and solvents. Answers: 1. Five Mechanisms of particle deposition Inertial Impaction: After the suspension of the particles in the air they have the tendency of traveling along with the air following the original path (Elimelech et al., 2013). If there is bend in the airways system i.e. there is blockage with in the path, then the particle stick to that material. This aspect depends on the velocity of the air and mass of the particles. Sedimentation: This mechanism is referred to the process of setting out of the particles in a congested way of the bronchioles and alveoli, while the airway measurement is small with slowly moving air. The terminal velocity of the particle influences the sedimentation. Electronic magnetism: Most of the aerial particles carry some specific charge. Charge gathering surface tends to entice and hold the oppositely charged particles (Hatch Gross, 2013). Diffusion: It is the main appliance for deposition of the subdivisions. The particles having 0.5 microns or less than it diffuse from the lower density region to the higher density region. Interception: When the particles are intercepted while travelling through the airway passageways the power of the particles traces the surface. This method is concerned for the fibers like Asbestos. Methods of integrated sampling: There are mainly two methods important for integrated air sampling. These are: high volume sampling and speciation sampling (Ding et al., 2013). The purpose of the speciation sampling is to understand the chemical composition of PM25, since the previous method is not capable of the characterizing the PM25 properly. Speciation sampling shows that sulfate, nitrates are the core components of this kind of sampling. High volume sampling method is conventional method of measuring the suspended particulate matter. It measures the compliances between the FRM and TSP particulate matter. But the TSP particles reduced day by day so the TSP method was diminished form the conventional way of checking the particulate matter. 2. Critical factors used in determining acceptable exposure levels to particulate materials: There are several factors utilized while determining the acceptable exposure levels to particulate materials. Some of the factors are described as follows: Chemical and biological composition of elements: Chemical composition of the substance many times determines the toxicity of the materials. This is known as the primary driver of the toxicity of the materials (Steinle et al., 2013). If the threshold value of the permissible exposure then the element is considered to be the biologically and chemically unstable element and they have quite high chance to enforce the exposure. Crystalline isotropic and structural form of particles:These structural positions the characteristics of some toxic materials. The molecule distributed in this manner tends to build the toxic elements. There is best known example of this: Silica (Zeitlin et al., 2013). These have the crystalline structure with in its molecules, which possess its toxic nature in the atmosphere. Shape of particle:Conventionally there are six types of asbestos available in the environment: amosite, chrysotile, crocidolite and three types fibrous. These elements vary for each chemical material. These factors affect the particle to be toxic and exposures. Size of particle:The toxicity of the material many times depends on the size of the particle. According the conventional theory about the particles, the size of the particles should not be very big, as it would be then suspended in the atmosphere easily, which causes the toxicity of the particle (Lepeule et al., 2012). This may empower the chances of exposure and toxic elements may be suspended in the air. Bigger the size of the particle the more the particle would be toxic in nature and will harm more and cause exposure. Concentration of the particles:Concentration of the particles also matters in case of measuring the toxicity of the materials. If the concentrations of the toxic materials are high in the atmosphere then it will empower the causes behind the exposure. This will cause the suspension of the toxic elements in the air. 10 nanogram of toxic element have the toxic range of 400 million in the air. So it is clear a very small amount of toxic element can harm human being and can cause the exposure (Smith et al., 2014). 3. Exposure factors: Here five crucial factors involved into the exposure of gasses, solvent and vapor are discussed as follows: Unstable organic complexes:VOCs are those compounds, which have the pressure of the vapor in its maximum range at the normal temperature. The high pressure of the vapor results into the low boiling point (Moya et al., 2014). This aspect enforces the molecules to evaporate fast from the surface of the solvent, gas. If the solvent or gas evaporates fast then there the chances of exposure is increased. The particles of the substances come closer to the point where they can easily be ignited. Temperature: This is another important factor for the exposure of the solvent, gas and vapor is the temperature. If the temperature of the surrounding is high than the normal one then there is a chance ofevaporation for the solvent as their boiling point is low. In case of the gas and vapor they are already in evaporated mode. So they become flammable easily, which may cause the exposure (Anderson et al., 2013). Concentration:If the concentration becomes high than a normal range, then it becomes easy to be exposable. The chances of exposure are increased for the solvents, gasses and vapors. Reactivity: This is also an important factor for the exposure of solvents, gas or vapors. Reactivity means how the materials react with moisture, air, acid and bases. There are several reactions can happen between the compounds like sulfate, nitrate. These elements can react with solvents, gas and vapor and the exposure may happen. So reactivity can be major factor for exposure of solvents, gas or vapors. Combustion rate: Combustion rate of any element like gas, solvent or vapor enforces the element to be ignited (Chai et al., 2015). There are several materials which have low chances to do the exposure but most of the gas, solvent and vapor have the high chances of combustion. References Anderson, T. C., Crawford, P. C., Dubovi, E. J., Gibbs, E. P. J., Hernandez, J. A. (2013). Prevalence of and exposure factors for seropositivity to H3N8 canine influenza virus in dogs with influenza-like illness in the United States.Journal of the American Veterinary Medical Association,242(2), 209-216. Chai, C. H., Khadijah, R., Chan, L. K. (2015).A phantom study on factors influencing exposure indicator (EI). Ding, F., Xu, W., Graff, G. L., Zhang, J., Sushko, M. L., Chen, X., ... Liu, X. (2013). Dendrite-free lithium deposition via self-healing electrostatic shield mechanism.Journal of the American Chemical Society,135(11), 4450-4456. Elimelech, M., Gregory, J., Jia, X. (2013).Particle deposition and aggregation: measurement, modelling and simulation. Butterworth-Heinemann. Hatch, T. F., Gross, P. (2013).Pulmonary deposition and retention of inhaled aerosols. Elsevier. Lepeule, J., Laden, F., Dockery, D., Schwartz, J. (2012). Chronic exposure to fine particles and mortality: an extended follow-up of the Harvard Six Cities study from 1974 to 2009.Environmental health perspectives,120(7), 965. Moya, J., Phillips, L., Sanford, J., Wooton, M., Gregg, A., Schuda, L. (2014). A review of physiological and behavioral changes during pregnancy and lactation: potential exposure factors and data gaps.Journal of Exposure Science and Environmental Epidemiology,24(5), 449-458. Smith, K. R., Bruce, N., Balakrishnan, K., Adair-Rohani, H., Balmes, J., Chafe, Z., ...Rehfuess, E. (2014). Millions dead: how do we know and what does it mean? Methods used in the comparative risk assessment of household air pollution.Annual review of public health,35, 185-206. Steinle, S., Reis, S., Sabel, C. E. (2013). Quantifying human exposure to air pollutionMoving from static monitoring to spatio-temporally resolved personal exposure assessment.Science of the Total Environment,443, 184-193. Zeitlin, C., Hassler, D. M., Cucinotta, F. A., Ehresmann, B., Wimmer-Schweingruber, R. F., Brinza, D. E., ...Burmeister, S. (2013). Measurements of energetic particle radiation in transit to Mars on the Mars Science Laboratory.Science,340(6136), 1080-1084.