Are irritants being sprayed into the environment? If so, what is the purpose?

This is definitely the case, and this is a significant downside of the chemtrails emanating from commercial aircraft especially, as they crisscross the skies in most of the developed world. The purpose is to degrade health and well-being and compromises in a number of ways. It aggravates those who suffer from pulmonary problems, but also those who have allergies will have an increase in their symptoms. The combined total liability, just as with other insults to the lungs, like smoking, will reduce the lifespan on average, and the irritant effects increase vulnerability to microbial pathogens being used as biowarfare by the interlopers. So the incidence and potential lethality from pulmonary diseases will increase.