Trigeminal (ocular and nasal) irritation comprises the dominant symptom complex in so-called "problem buildings". Imputed etiologic agents in indoor air include extremes of temperature and humidity, the presence of volatile organic compounds, combustion products (including tobacco smoke), ozone (from office machines), and products of indoor air chemistry. In addition to producing primary irritation, mucosal irritants trigger a variety of secondary reflex symptoms, such as nasal congestion, rhinorrhea, and sinus pressure, and may predispose to infection in the form of sinusitis and otitis media. Marked variability in self-reported sensitivity to indoor air pollutants has been observed, with females, younger individuals, and people with allergies reporting more symptoms. We report on a series of experiments designed to uncover demographic patterns of "nasal irritant sensitivity", as well as potential mechanism(s) involved in observed chemesthetic variability.