Particulate matter ultrafine particles

One hint of possible trouble to come is provided by the information we described in Chapter 4, related to airborne particulate matter (PM). The available evidence ascribes significant increases in the risks of asthma and other respiratory diseases, certain cardiovascular conditions, and lung cancer to PM exposure, particularly those that average less than 2.5 pm (2500 nm) in size. As we noted, the chemical composition of these particles varies widely, depending upon source, but may not be as important as particle size as a risk determinant. Moreover, there is some experimental evidence pointing to the so-called ultra-fines, PM with dimensions below 100 nm, as significant contributors to PM risk. In addition some experimental studies have demonstrated that ultrafines not only distribute themselves throughout the airways, but seem to be able to translocate to other parts of the body - liver, heart, perhaps the CNS. 

The link between exposure to air pollutants and adverse health effects is well established, but the causal biological mechanisms are not clear and this is especially the case for particulate matter health effects. Airborne particulate matter is extremely variable in chemical composition, size and morphology all parameters of possible health relevance. This and the different health endpoints affected by exposure to ambient PM make the situation very complex. It may well be that more than one particle characteristic is needed to effectively describe the harmful outcomes of exposure. Possible parameters under discussion are particle number concentration, which is dominated by particles below 100 nm in size the so-called ultrafines [33], particle surface area concentration, which is dominated by particles around 200-800 nm in diameter [34, 35], black carbon or black smoke [36], or the reactivity of particles with respect to redox reactions, or their potential to form radical oxidative species (ROS) [37]. These and some other alternative particulate indicators are currently discussed [38] and investigated in several large European and US studies such as ESCAPE and Transphorm2. 

Morawska and co-workers have produced a number of review articles on this topic. For example, Holmes and Morawska [20] reviewed several simple and complex models covering a wide range of urban scales for the dispersion of particulate matter. Morawska et al. [21] focused on vehicle produced ultrafine particles and discussed limitations of measurement methods, sources, characteristics, transport and exposure of these particles in urban environments. Their further review focused on indoor and outdoor monitoring of airborne nanoparticles [3]. Morawska [22] discussed the importance of airborne ENPs from the health perspective. Regulations and policy measures related to the reduction of ambient particulate matter were discussed in their follow-up article [23], Their recent review article discussed the commuters exposure to ultrafine particles and associated health effects [24]. 

Several epidemiological studies show that fine and ultrafine (<0.1 pm) particulate matter and air pollution can pose adverse health effects including respiratory, cardiovascular, allergic, and carcinogenic diseases (Kiinzli et al., 2000 Donaldson et al., 2003 Bernstein et al., 2004). It appears also that ultrafine particles, after deposition in the lung and gain access to the pulmonary interstitium, can penetrate the systemic circulation and exert more toxicity than coarse and fine particles (Oberdorster, 2001 Bernstein et al., 2004). 

Atmospheric particles influence the Earth climate indirectly by affecting cloud properties and precipitation [1,2], The indirect effect of aerosols on climate is currently a major source of uncertainties in the assessment of climate changes. New particle formation is an important source of atmospheric aerosols [3]. While the contribution of secondary particles to total mass of the particulate matter is insignificant, they usually dominate the particle number concentration of atmospheric aerosols and cloud condensation nuclei (CCN) [4]. Another important detail is that high concentrations of ultrafine particles associated with traffic observed on and near roadways [5-7] lead, according to a number of recent medical studies [8-11] to adverse health effects. 

Concentration of particles in the air as well as particle size distributions can be considered either in terms of particle number or mass. In terms of number, the vast majority of airborne particles are in the ultrafine range. For example, in urban outdoor air where motor vehicle emissions are a dominant pollution source, over 80% of particulate matter in terms of number is in the ultrafine range [17]. Since outdoor particles contribute significantly to indoor particle concentrations, also in indoor air particle number concentration is usually dominated by the smallest particles. However, most of the mass of airborne particles is associated with large particles since the mass of ultrafine particles is often very small in comparison with the mass of larger particles. The particle surface area in turn is largest for particles somewhat above the ultrafine size range. 

A potent parameter driving the inflammation is the surface area of the particles. It is known that the ability of model ultrafine particulate matter to induce oxidative stress is not due to their composition but is related directly to their surface area [10-12]. 

Measurements performed at the exhausts of commercial residential heating devices have shown that particulate matter emission is negligible below the detection limit of instruments based on mass measurement. However, there is increasing evidence that the concentration of the "number" of particles (related to their size) rather than their cumulative mass might be responsible for the observed effects of particulate on health and the environment. For these reasons it is important to control the emission of the number of particles of specific sizes, rather than their mass from combustion systems that are widely used, such as residential burners. In particular, the interest should be focused on the ultrafine emitted particles, those with mean sizes below 100 nm that, because of the low sizes, do not contribute massively to mass emission. 

Particles that can be inhaled, those less than 10 p,m (10,000 nm PMIO) can be separated by the high volume cascade impactor (HVCI) into four fractions. When the HVCI was used to collect organic urban aerosols presumably from transportation, combustion, and the Earth s crust, the breathable particulate matter (PM) was divided into PM 10 to 2.5 p.m (coarse aerosols, which are mechanically produced), and the PM 2.5 to 1 p.m (intermodal) fiaclion, which is expected to have particles that contain properties of both coarse (larger) and fine (smaller) aerosols. In addition it separates the PM 1 to 0.2 p,m (1000 to 200 nm accumulation) fraction (just larger than nano- or ultrafine particles with properties similar to those particles) and PM 0.2 (particles <200 run diameter in air) firaction. The cutoff size (200 nm) was chosen for convenience. 

Mitschik S, Schierl R, Nowak D et al (2008) Effects of particulate matter on cytokine production in vitro a comparative analysis of published studies. Inhalation Toxicol 20 399-414 Mtiller W, Felten K, Sommerer K et al (2008) Deposition, retention, and translocation of ultrafine particles from the central airways and lung periphery. Am J Respir Crit Care Med 177 426 32... 

Rundell KW, Hoffman JR, Caviston R et al (2007) Inhalation of ultrafine and fine particulate matter dismpts systemic vascular function. Inhalation Toxicol, doi 10.1080/08958370601051727 Saldiva PH, Clarke RW, Coull BA et al (2002) Lung inflammation induced by concentrated ambient air particles is related to particle composition. Am J Respir Crit Cate Med 165 1610-1617... 

Sioutas C, Koutrakis P, Burton RM (1995) A technique to expose animals to concentrated fine ambient aerosols. Environ Health Perspect 103 172-177 Sioutas C, Delfino RJ, Singh M (2005) Exposure assessment for atmospheric ultrafine particles (UFPs) and implications in epidemiologic research. Environ Health Perspect 113 947-955 Southern Ontario Centre for Atmospheric Aerosol Research (SOCAAR) (2007) FacUities-Concentrated Ambient Particle Exposure Facility (CAPEF). http //www.socaar.utoronto.ca/ fac-inst/Facilities.htm. Accessed 21 September 2009 Squadrito GL, Cueto R, Dellinger B et al (2001) Quinoid redox cycling as a mechanism for sustained fiee radical generation by inhaled airborne particulate matter. Free Radic Biol Med 31 1132-1138... 

Elder A, Gelein R, Silva V et al (2006) Translocation of inhaled ultrafine manganese oxide particles to the central nervous system. Environ Health Perspect 114 1172-1178 European Union (1999) Council Directive 1999/30/EC of 22 April relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. Off J Eur Communities L163(29/06). 

Koponen I, Asmi A, Keronen P et al (2001) Indoor air measurement campaign in Helsinki, Finland 1999—the effect of outdoor air pollution on indoor air. Atmos Environ 35 1465-1477 Kubo S, Nakano M, Kondo T, Yamamoto M (2006) Formation characteristics of diesel nanopartieles. Trans Jap Soc Mech Eng 72 2612-2618 Kulmala M, Vehkamaki H, Petaja T et al (2004) Formation and growth rates of ultrafine atmospheric particles a review of observations. J Aerosol Sci 35 143-176 Leech J, Nelson W, Burnett R et al (2002) It s about time a comparison of Canadian and American time-activity patterns. J Expos Anal Environ Epidemiol 12 427-432 Mathis U, Mohr M, Zenobi R (2004) Effect of organic compounds on nanoparticle formation in diluted diesel exhaust. Atmos Chem Phys 4 609-620 Mejia J, Morawska L, Mengersen K (2008) Spatial variation in particle size distributions in a large metropolitan area. Atmos Chem Phys 8 1127-1138 Moschandreas D, Saksena S (2002) Modeling exposure to particulate matter. Chemosphere 49 1137-1150... 

Hohr D, Steinfartz Y, Schins RP, Knaapen AM, Martra G, Fubini B, Borm PJ (2002) The surface area rather than the surface coating determines the acute inflammatory response after instillation of fine and ultrafine Ti02 in the rat. Int J Hyg Environ Health 205 239-244 Hopke PK, Rossner A (2006) Exposure to aitbome particulate matter in the ambient, indoor, and occupational environments. Clin Occup Environ Med 5 747-771 Host S, Larrieu S, Pascal L, Blanchard M, Declercq C, Fabre P, Jusot JF, Chardon B, Le Tertre A, Wagner V, Prouvost H, Lefranc A (2008) Short-term associations between fine and coarse particles and hospital admissions for cardiorespiratory diseases in six French cities. Occup Environ Med 65 544—551... 

Various health effects have been reported from short-term studies. Increased mortality associated with short-term exposure is the most important health outcome in these studies. A multiplicity of studies from various settings in the US, Canada and Europe attest the association of different metrics of particular matter (PMio, PM2.5, PMio 2.5 or ultrafine particles) with general and cause specific human mortality. In the first line are daily time series studies from single cities (e.g. Schwartz 1991). More relevant are analyses that pool data from several locations, using a common protocol for analysis of the within-city data and then combining estimates from various locations in order to gain precision and to evaluate the heterogeneity of the effect of particulate matter across the cities. 

USEPA (2009) Particulate Matter National Ambient Air Quality Standards scope and methods plan for health risk and exposure assessment. Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency. Research Triangle Park, NC 27711 Viana M, Amato F, Alastuey A et al (2009) Chemical tracers of particulate emissions from commercial shipping. Environ Sci Technol 43 7472-7477 Wallace LA, Emmerich SJ, Howard-Reed C (2004) Source strengths of ultrafine and fine particles due to cooking with a gas stove. Environ Sci Technol 38 2304-2311 Wardoyo AYP, Morawska L, Ristovski ZD et al (2006) Quantification of particle number and mass emission factors from combustion of Queensland trees. Environ Sci Technol 40 5696-5703... 

Urban levels of air pollution (downtown Sao Paulo) modified the progression of urethane (3 g/ kg)-induced lung tumours in mice (Cury etal. 2000). Urban particles consist of three modes ul-trafine particles, accumulation mode particles (which together form the fine particle mode) and coarse mode particles. Ultrafine particles (those of <100nm diameter) contribute very little to the overall mass, but are very high in number, which in episodic events can reach several hundred thou-sand/cm in the urban air. The hypothesis that ultrafine particles are causally involved in adverse responses seen in sensitive humans is based on several studies summarised by OberdOrster (2001). Timblin etal. (2002) demonstrated the development of dose-related proliferation and apoptosis after exposure of an alveolar epithelial cell line (CIO) to particulate matter or to ultrafine carbon black, a component of particulate matter. Ribonuclease protection assays demonstrated that increases in mRNA levels of the early response protooncogenes c-jun, junB, fra-l, and/ra-2 accompanied cell pro-hferation at low concentrations of particulate matter whereas apoptotic concentrations of particulate... 

Most of the PM mass from diesel engines ranges from 0.1 to 0.5 xm in diameter, which is much less than the suspended particulate matter (SPM) standard prescribed in the Air Quality Standards of Japan (10 xm or less), and the PM2.5 (2.5 p,m or less) standard prescrihed hy the United States Environmental Agency. To make matters worse, the majority of PM is made up of ultrafine particles with diameters of 0.005-0.1 xm. Ultrafine particles of 0.05 xm or smaller are called nanoparticles, and these cause concern with regard to invasion of respiratory organs such as bronchial tubes, alveolar eells, and further Wood vessels, and are thus detrimental to human health. ... 

Diesel particulate matter (PM) is a complex multi-phase multi-component material, which is traditionally and conveniently divided into three main fractions a solid fraction mainly comprising carbon particles and ash, a soluble organic fraction where the m ority of the hydrocarbons originating from the lube oil and fuel are concentrated, and sulfate particulates derived from the sulfur content of the fuel. The sizes of particulate matter from diesel engines are characterized by a distribution spread (Fig. 11.1) PMIO (diameter less than 10 pm), fine particles (less than 2.5 pm), ultrafine particles (less than 0.1 pm) and nanoparticles (less than 50 nm). ... 

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