Airborne nanoparticles

We further suggest that silane is produced and becomes airborne, which then reacts with metal or metal silicide nanoparticles that have not reacted with silicon or with Co silicide nanostructures to produce SiNW, as shown in Scheme 1. We are looking into how to directly prove the existence of silane. 

This chapter begins by summarising the recent review articles on this topic. Other topics such as sources and physico-chemical characteristics of ambient and emerging nanoparticles (i.e. ENPs) are then covered briefly for the completeness of the article. This is then followed by the assessment of nanoparticles in numerous European cities, estimation of respiratory deposition doses and a brief discussion on current and future prospects of their regulatory control. In what follows, the terms airborne nanoparticle and ENP refer to total particles, currently mainly produced by vehicles, and nanomaterials-derived products, respectively. 

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]. 

The ever-increasing number of published studies on airborne nanoparticles, which is also evident from the brief summary of various reviews presented above, clearly demonstrates a mounting importance of this research topic among the air quality science and management communities. 

A considerable amount of development has happened in the last two decades in the area of measurements, dispersion modelling and exposure assessment studies related to airborne nanoparticles. This is clearly evident from the ever-increasing number of published studies in Europe, and elsewhere in general. This study presented PNCs over 45 sampling locations covering about 30 cities and 15 European countries. While reviewing the literature, it was felt that there are still a number of European countries where nanoparticle-related studies are scarce. 

Airborne nanoparticles empirically fit well to log normal distributions and exhibit bimodal distributions in atmospheric urban environments. These arise from both natural and anthropogenic sources. Road vehicles remain a dominant source, contributing up to 90% of total PNCs, in polluted urban environments. 

ENPs are emerging class of airborne nanoparticles having a main impact on the air quality of indoor environments these are unintentionally released into the ambient environment during the manufacture (commercial or research), handling, use or disposal of nanomaterials integrated products. Their physical and chemical characteristics differ from other nanoparticles produced through traffic [4], The health consequences of their inhalation are not yet well known. A number of studies have reported their number concentrations and size distributions in workplaces but their concentrations in ambient urban environments are largely unknown and warrant further research. Adequate methods have yet to be developed to quantify them in the presence of nanoparticles from other sources. 

Morawska L, Wang H, Ristovski Z, Jayaratne ER, Johnson G, Cheung HC, Ling X, He C (2009) JEM spotlight environmental monitoring of airborne nanoparticles. J Environ Monit 11 1758-1773... 

Kumar P, Fennell P, Robins A (2010) Comparison of the behaviour of manufactured and other airborne nanoparticles and the consequences for prioritising research and regulation activities. J Nanopart Res 12 1523-1530... 

Morawska L (2010) Airborne engineered nanoparticles are they a health problem Air Qual Climate Change 44 18-20... 

Evaluation of the content of PGMs in airborne particles and dusts is important because of the possibility of their inhalation and accumulation in human lungs. Nanoparticles from autocatalysts can be transported into various parts of the environment (waters, plants, soils, and sediments) and transformed into more bioavailable species. There are data on the higher solubility of platinum from tunnel dusts than from inorganic species emitted from converters [30]. Distribution and accumulation of metals depend on traffic density, distance from the road, and meteorological conditions (wind, rain). The age of an autocatalyst and speed conditions directly affect the amount of nanoparticles released from catalytic... 

Evidence indicates exposure to nanoparticles can induce an inflammatory response in the CNS. For example, when a sample of mice were exposed to airborne particle matter, increased levels of pro-inflammatory cytokines (TNF-a IL-la), transcription factor, and nuclear factor-kappa beta (NF-k/3) were observed (114). TNF-a serves a neuroprotective function (115), but given certain pathogens TNF-a can be neurotoxic (116-120). IL-a activates cyclooxygenase (COX)-2, phospholipase A2, and inducible nitric oxide synthase (iNOS) activity, which are all associated with inflammation and immune response (121). IL-a is also partially responsible for increasing the permeability of the blood-brain barrier (122, 123). Thus, there is great interest in better understanding how nanoparticles enter the body and translocate as this will impact all organs and thus the toxicity of nanomaterials. 

The airborne diameter of MgO nanoparticles was 15,000 nm, similar to an urban aerosol (57b). At that size, less than 5% of the mass and less than 35% of the surface area would enter the deep lung, evade phagocytosis, and be available to the interstitial space. Moreover, that which was available to the lung s interstitial space would not persist (24b, 25), irritate, or injure the lung tissue. Likewise if MgO nanopaiticles were spilled in the environment, conventional sodium bicarbonate would facilitate their rapid dissolution into aqueous magnesium salts. In the human body, excess magnesium is used for many biochemical reactions, and is cleared within a short time (57c). 

Various nanotechnologies used in fabrication and manufacturing have been around for several years now and there is currently very little disagreement about the potential benefits that could be realized by their increasing implementation in industry. However, one major area of concern in the application of nanotechnologies in manufacturing is the subsequent potential compromise of worker health and safety due to airborne nanoparticles produced during their application. 

The purpose of this chapter is to present an overview of the current state of the literature regarding nanoparticles in the workplace and environment and their associated health effects as well as to provide the latest characterization techniques used to conduct airborne nanoscale particle measurement. In doing so, the advantages and disadvantages to the use of each of these characterization techniques are elucidated, while efforts are made to restrict the discussion to only those potential applications in industries utilizing nanotechnologies in their processes. 

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