Nonallergic Rhinitis: Environmental Determinants.

"Nonallergic rhinitis" (NAR) is defined by intermittent or persistent nasal symptoms without evidence of immunoglobulin E-mediated sensitization to relevant aeroallergens. The largest subgroup is idiopathic, and is characterized by nasal hyperreactivity to nonspecific environmental triggers, including temperature, humidity, and chemical exposures. As nonspecific nasal hyperreactivity is often found in the absence of mucosal inflammation, some clinicians refer to this condition as "nonallergic rhinopathy." Irritant rhinitis, can arise de novo after high-level and/or prolonged exposure to airborne irritant chemicals. We review the range of environmentally induced nonallergic nasal symptoms and signs, and explore issues of pathophysiology unique to environmental chemical exposures.