Page 417 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

13.2 Exposure to Nanoaerosol 397

Fig. 13.1 Environmental impact of nanoaerosol

Nanoparticles in certain size range can transport toxic chemicals into the human
body through the respiratory system. These chemicals may cause more damage than
their counterparts in micron size range. Comparison between the rat’s exposure to
250 and 20 nm titanium oxide (TiO 2 ) aerosol particles of the same weight showed
that more 20 nm particles were trapped in the lung, resulting in inflammation [12].
Similar studies showed that exposure to 30-nm Teflon particles, which are con-
sidered as inert at micron level, led to acute pulmonary toxicity in rats [27].
Nanoparticles can cause adverse health effects due to the direct action of the
particles or to their rate as carriers of toxic elements [61]. Because nanoparticles are
not removed from the upper respiratory tract, they are inhaled into the deeper areas.
Their rather high deposition (more than 90 %) in the alveolar region or other
respiratory tract regions leads to their subsequent entry into the blood stream [7, 58].
The small size and large surface area of nanoparticles enable significant interaction
with biological systems. Nanoaerosols may also cause toxic effects on other organs.
Nanoaerosols deposited in alveolar region or other respiratory tract region can lead
to diffusion into the circulatory system [58], and they can reach the brain and the
heart. A direct interaction of particles (or compounds generated by particles) with
DNA is considered possible. Therefore, there may be a great risk of carcinogenicity.
The most important toxic effects are induced by nanoaerosol inhalation, and
thereby chronic toxicity and carcinogenicity in the lungs [39]. Since the size of
nanoaerosol particles is smaller than cells, they can penetrate through the respiratory