The most common cause of nasal congestion is allergy to inhalants, such as pollen, molds, dust mites, trees, or animal dander. Exposure to various chemicals in the home or workplace may also contribute to allergic rhinitis. Indoor and outdoor air pollution may also be a factor in susceptible people. Smoking and secondhand exposure to tobacco smoke have been implicated in chronic nasal congestion⁹ and the prevalence of chronic rhinitis among men has been shown to increase with increasing cigarette consumption.¹⁰ People exposed to chlorine, such as lifeguards and swimmers, may also be at risk of developing nasal congestion.¹¹

Careful evaluation by an allergist or other healthcare professional may help identify factors contributing to nasal congestion. Sometimes strict avoidance of the triggering agents (e.g., thoroughly vacuuming house dust or using dust covers on the mattresses) may provide relief. Where complete avoidance of irritants is not possible, desensitization techniques (immunotherapy [allergy shots]) may be helpful.

Nasal irrigation with warm water or saline may be helpful for reducing symptoms of sinus congestion, although steam inhalations appear to be less useful. In a study of people suffering from the common cold, steam inhalation did not improve sinus congestion any better than placebo.¹² In a similar controlled study, irrigation of the nasal passages with heated water or saline, decreased nasal secretions, although inhalation of water vapor did not.¹³