Respiratory Impact of Lifestyle Flashcards
particulates
term relates to exposure to a dry aerosol composed of separate particles which are themselves scientifically defined as very small pieces of solid matter
risk equation
risk = hazard x exposure
importance of size
nanoparticles cause more inflammation than the same mass of fine respirable particles composed of the same material
what is based upon aerodynamic diameter
penetration of the lungs (and deposition)
inhalable fraction
the mass fraction of total airborne particles which is inhaled through the nose and mouth
extrathoracic fraction
the mass fraction of inhaled particles failing to penetrate beyond the larynx
thoracic fraction
the mass fraction of inhaled particles penetrating beyond the larynx
respirable fraction
the mass fraction of inhaled particles penetrating to the unciliated airways
the aerodynamic diameter
defined as the diameter of a unit density sphere with the same settling speed as the particle of interest
fibres
defined as having a length greater than 5um, diameter less than 3um and a length to width ratio of greater than 3:1
naturally occurring fibres
asbestos
pele’s hair
plant fibres (e.g. cotton)
man-made fibres
insulation wools
refraction ceramic fibres
silicon carbide
carbon nanotubes
normal clearance - what does failure of normal movement result in
an inability to clear long fibres out of the lungs
what happens after fibre exposure
deposition of short or long fibres
what happens after deposition of short fibres
effective phagocytosis and macrophage clearance
what are the classifications of long fibres
non-biopersistent
biopersistent
what happens to non-biopersistent long fibres
dissolution
what happens to biopersistent long fibres
incomplete phagocytosis, cell activation and failed clearance
what does incomplete phagocytosis, cell activation and failed clearance lead to
inflammation, fibrosis, cancer
what happens after dissolution of non-biopersisitent long fibres
breakage which leads to short fibres and subsequent effective phagocytosis and macrophage clearance
OR
they dissolve
fibre biopersistence - physiological processes
clearance (mucociliary, macrophage mediated)
translocation
fibre biopersistence - physicochemical processes
biodurability - dissolution, leaching, breaking with extracellular or intracellular environment
what does fibre biopersistence lead to
retention - either short or long
short retention
non-pathogenic - limited inflammatory response
long retention
pathogenic - chronic inflammation, fibrosis, cancer
