Particulate matter exposure modelling

Using a one-dimensional Monte Carlo analysis to estimate population exposure and dose uncertainty distributions for particulate matter, where model inputs and parameters (e.g. ambient concentrations, indoor particulate matter emission rates from environmental tobacco smoke, indoor air exchange rates, building penetration values, particle deposition rates) are represented probabilistically with distributions statistically fitted to all available relevant data. 

Keywords Exposure, Health effects, Modelling, Particulate matter Contents... 

Burke JM, Zufall MJ, Ozkaynak H (2001) A population exposure model for particulate matter case study results for PM2.5 in Philadelphia, PA. J Expo Anal Environ Epidemiol 11 470-489... 

We focus in this chapter on particles from ambient origin. We first illustrate differences in outdoor and personal exposure using data on real-time particle number concentrations (PNC) from a recent study in Augsburg, Germany. We then present a model of indoor PM concentrations, illustrating the factors that affect indoor air quality. We summarize empirical studies that have assessed indoor-outdoor relationships for particle mass, particle number, and specific components of particulate matter. The focus is on European studies, but we included key studies from outside Europe as well. We conclude by comparing the strength of indoor-outdoor relationships of various particle fractions and components. 

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]. 

Oxidation-reduction (redox) reactions, along with hydrolysis and acid-base reactions, account for the vast majority of chemical reactions that occur in aquatic environmental systems. Factors that affect redox kinetics include environmental redox conditions, ionic strength, pH-value, temperature, speciation, and sorption (Tratnyek and Macalady, 2000). Sediment and particulate matter in water bodies may influence greatly the efficacy of abiotic transformations by altering the truly dissolved (i.e., non-sorbed) fraction of the compounds — the only fraction available for reactions (Weber and Wolfe, 1987). Among the possible abiotic transformation pathways, hydrolysis has received the most attention, though only some compound classes are potentially hydrolyzable (e.g., alkyl halides, amides, amines, carbamates, esters, epoxides, and nitriles [Harris, 1990 Peijnenburg, 1991]). Current efforts to incorporate reaction kinetics and pathways for reductive transformations into environmental exposure models are due to the fact that many of them result in reaction products that may be of more concern than the parent compounds (Tratnyek et al., 2003). 

Deterministic sensitivity analysis performed during modelling of population exposures to ambient fine particulate matter by using high (H), medium (M) and low (L) values during the analysis of the impact of uncertainties associated with key inputs and parameters on model predictions (e.g. time spent outdoors [H = 95%, M = 80%, L = 50%], residential building infiltration fractions [H = 0.7, M = 0.5, L = 0.2], deposition rates [H = 0.4, M = 0.3, L = 0.1]). 

The developed modelling system can be used to plan field campaigns, interpret measurements, and provide the capacity for forecasting oxidants, particulate matter and toxics. Also, it can be used to provide guidance to evaluate exposure studies for people, animals, crops and forests, and possibly for epidemiological studies. 

Chemistry will play a large role in the research areas of our own strategic plan. For example, work on particulate matter will allow us to understand the nature of the particles and their behavior in the atmosphere, develop the modeling that will predict their fate and transport along with the resulting human exposure, and understand the transition from exposure to dose that will enable health assessment work. 

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... 

From this discussion, it follows that characterisation of the physical and chemical environment of the reactive sites of a particle on a molecular level will be required to better understand its fate in the atmosphere. Exposure experiments should be continued, not only using simplified model systems, but also using natural combustion related aerosols of various particle size and matrix composition. Filter exposures of particulate matter should yield more detailed information on sampling artifacts. Exposure of aerosol particles to gaseous compounds should be tried in a static or... 

It is, however, worth noting that particulate matter and emissions of heavy metals were not yet modelled in USEtox at the time of analysis. In addition, the employed USEtox version is not designed to assess indoor exposure to toxics such as formalin. NO3 emissions from reeling have no assessed eutrophication potential in freshwater as phosphorous is considered to be the limiting factor for EE (Goedkoop et al., 2013). 

Figure 12 Simulation model results of the accumulation of particles in the lungs of several species after chronic exposure to an atmosphere containing 0.5 mg/m of particulate matter. (From Ref 32.)...

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