TABLE 5.

Medical conditions requiring caution with masking

Condition	Possible adverse impact of masking and relevant studies	Suggested mitigation
Allergic rhinitis	Mask-induced worsening of rhinorrhea (269), though masks may also reduce exposure to environmental allergens (e.g., pollen) (270)	Experiment with different designs and situations. Exemption may be needed when mandates are in place.
Alzheimer’s disease	Impossible to achieve consistent fit and adherence [people with severe Alzheimer’s did not wear masks properly or at all during pandemic peaks (271, 272)]	Focus on other preventive measures, including indoor air quality, reduced mixing, and masking of staff and visitors
Chronic lung disease	Subjective difficulty in breathing because of increased breathing resistance, especially during exercise (234); in severe lung disease, theoretical (but not empirically demonstrated) risk of compromised gas exchange.	People with mild and well-controlled asthma can usually mask normally; those with more severe respiratory conditions should be assessed individually. If necessary, avoid indoor crowded situations. Low-breathing resistance respirators may be better tolerated. Exemption may be needed.
End-stage kidney disease	Decrease in oxygenation and increased respiratory effort, of uncertain clinical significance (based on a single small study conducted during the 2003 SARS-1 outbreak) (273)	Assess individually, taking account that such people may be vulnerable to severe complications if infected. Avoid indoor crowded situations.
Epilepsy	Risk of hyperventilation, which could theoretically trigger a seizure (based mainly on expert opinion) (274, 275).	Avoid indoor crowded situations. Mask should be removed from anyone having a seizure. Exemption may be needed.
Facial conditions	Facial trauma or surgery and painful conditions of the face (e.g., trigeminal neuralgia) may make masking difficult or painful [no empirical studies but often mentioned in guidance (233)].	Assess individually; exemption may be needed.
Heart failure	Possible deterioration of cardiopulmonary function during exercise (276)	Test to see if mask is tolerated during indoor exercise. If symptomatic in such situations, exercise outdoors.
Laryngeal or tracheal surgery	People with laryngectomy or tracheotomy are at greatly increased risk of respiratory infections, and some are immunocompromised (e.g., during cancer treatment) (277).	Mask should be worn over the tracheotomy.
Mental health conditions (e.g., anxiety, autism, depression, and claustrophobia)	Worsening of anxiety, panic, and sense of suffocation (278–280). People who have experienced trauma may feel profound distress while masking (281).	Experiment with different designs (an elastomeric respirator with high breathability may be less symptom inducing). Take frequent breaks. Grounding techniques can be helpful for trauma-related anxiety. Exemption may be needed.
Pregnancy-related conditions	Pregnancy is a high-risk state for complications of COVID-19 (including miscarriage); empirical evidence on masking in pregnancy is limited (240). A single-challenge study in 20 pregnant health-care workers showed changes in some physiological variables (e.g., tidal volume) with respirator materials (282). That study had major design flaws (e.g., breathing was not through an actual respirator but through a tiny segment of N95 filter material cut from a respirator).	While definitive evidence is lacking, masking during strenuous exercise or demanding physical work when pregnant is not advised. In other situations, advantages of masking while pregnant appear to outweigh disadvantages.