AIR POLLUTION – MONITORING MODELLING AND HEALTH

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Air Pollution – Monitoring, Modelling and Health
farming operations, the nano-aerosol fraction is composed of particulate matter and
microbial compounds, including endotoxins, such as LPS, and peptidoglycans (PGNs). The
latter compound class represents cell wall constituents particularly of gram-positive
bacteria. (Poole et al., 2008)
1.3 Particle deposition and clearance within the human respiratory tract
Deposition of inhaled particles in the human respiratory tract is determined by several
biological factors, such as lung morphology and breathing patterns, as well as by physical
factors, such as fluid dynamics, particle properties, and deposition mechanisms. Since
particle deposition in individual airways cannot be thoroughly analyzed in-vivo , particle
inhalation and the corresponding deposition patterns are simulated by analytical computer
models, which require regular comparison with experiments obtained from human
subjects. (Hofmann, 2011) In principle, particle deposition within the respiratory tract is bound to
physical principles such as impaction, gravitational settling, diffusion, and electrical
attraction (Figure 2).
With the introduction of particle filters and catalytic converters in the exhaust stream, most
coarse particles are efficiently removed. Filtering out the coarse fraction usually leaves the
smaller without the coarser sibling where the former tend to agglomerate on. Due to their
minute dimensions, nano-sized particles largely escape filtering devices and are emitted into
the environment where they interact photochemically to form secondary by-products. Upon
inhalation, nano-aerosols, along with the adsorbed semi-volatile / volatile chemical cocktail
predominantly deposit via Brownian diffusion and electrostatic mechanisms in the nose and
the alveolar region where they can unfold their toxicological potential. (Donaldson et al., 1998)
Fig. 2. Total deposition function versus particle diameter for an adult individual with a
tidal lung volume of 660 mL at 30 breaths per minute (left). Particle regime 300 nm by sedimentation and
impaction. (modified after Hussain et al., 2011) On the right a schematic view of the pulmonary
domains is shown, with the naso-pharyngeal and tracheo-bronchial pathway at the top
and the bronchiole and alveolar regime at the bottom, alongside the flow velocities of the
in-/exhaled air. (modified after Yip., 2003)