Low humidity → respiratory and mucous-membrane problems

• A review of indoor-air humidity effects found that when relative humidity (RH) is too low (e.g. in winter, heating season), there is an increased incidence of upper airway symptoms, allergies, and respiratory tract irritation. PubMed+1

• Experimental and epidemiological data show that maintaining indoor RH between 40% and 60% helps minimize survival or infectivity of many airborne viruses or bacteria vs. dry air. PubMed+2Scientific Research Publishing+2

• Conversely, in “dry air” environments (low RH), mucociliary clearance in human airways is impaired — meaning the body’s natural defense (trapping & removing pathogens) is less effective. CDC Stacks+1

• A large recent population-based study (age 40+) showed a significant association between low ambient humidity and worse lung function / more respiratory symptoms. SpringerLink

Conclusion: Dry indoor air — common in heated homes or during winter — can contribute to respiratory irritation, infections, and reduced immune defense in the airways.