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					Originally Posted by RolloTomasi  Small airway disease resulting from inhalation of environmental contaminants is not thought to cause or exacerbate EIPH? | 
	
 Yes, small airway disease such as chronic inflammation, allergy does exacerbate EIPH.   Yes, environmental contaminants (air pollution, ammonia in air from stall, chronic dust in air from straw/hay) can cause small airway disease.
Dirt in the airways from inhalation racing doesn't get down to the bronchioles, let alone alveoli. It stays in the first 4 generations of lung branching (in the trachea and major bronchi) and is readily moved up and out by cilliary action in most cases.  Not a big contributor to airway inflammation.  Just like dirt inhaled into your nose when you dirt bike or run in a dusty place is snotted out readily, and doesn't give you an asthma attack.   Dust in the air doesn't get down there, either.  A particle has to be particular micron size to make it down there.  Nature's design is good.