Air pollution by ammonia is produced mostly from animal husbandry. It reacts with acidic air pollutants (HNO3, H2SO4) to the corresponding salts which make a considerable part of the fine dust in air.

I would expect such dust particles to dissolve inside our lungs and cause a small increase in the blood concentration of NH4+, NO3- and SO42-, negligible compared for example to the several g/d of ammonia that result from excess consumption of protein in Western diet. Thus, unlike, say, soot particles with bound polycyclic hydrocarbons, such salt particles should not directly harm humans (indirect effects from excess nitrogen in the environment are, of course, a different story).

Am I missing something here?