Background: Studies have shown that poor shelter or dwelling conditions may lead to deteriorations in health. Those with asthma may be more susceptible to compromised living conditions and stress leading to a higher risk of asthma exacerbations. To describe the asthma control and quality of life of individuals with diagnosed asthma living in a shelter in Damascus, Syria and estimate the prevalence of respiratory symptoms in shelter dwellers without diagnosed asthma. Methods:In this cross-sectional study, all individuals 5 years and older living in Al-Herjalleh shelter with diagnosed asthma were recruited to complete a questionnaire, which included items related to their respiratory symptoms, asthma exacerbations, exposure to asthma triggers, medication use, and health-related quality of life before and since entering the shelter. A representative sample of shelter dwellers without diagnosed asthma also completed a questionnaire to establish their demographics, respiratory symptoms, environment and chronic disease co-morbidities, in order to identify factors associated with under-diagnosed asthma. All participants underwent spirometry to measure their lung function. Descriptive statistics were calculated, and chi-square tests and Student's t-tests were used to compare individuals with asthma before and since entering the shelter, as well as to compare those with under-diagnosed asthma and individuals without asthma.Results: The prevalence of asthma at the Al-Herjalleh shelter in those aged 5 years and older was approximately 8.5%. Nearly 70% of the asthma group felt their asthma had worsened since entering the shelter, and there was a significant drop in the proportion of individuals using inhaled corticosteroids (ICS), with only 4.3% using daily ICS in the shelter (P<0.0001). The proportion of individuals experiencing a severe asthma attack did not change after entering the shelter (P=0.97), but almost all individuals with asthma (94.4%) reported worsening in their health-related quality of life. In the non-asthma group, 44.2% of participants reported episodes of wheezing, coughing and breathlessness at night, consistent with underdiagnosed asthma. A higher proportion of those with under-diagnosed asthma had allergic rhinitis (57.1%), symptoms of post-traumatic stress disorder (PTSD) (35.1%), and abnormal spirometry (60.0%), compared to those without asthma. Conclusions:The findings of our study highlight the need for asthma programs in Syrian shelters as significant gaps exist in both the screening and management of chronic respiratory diseases to minimize asthma deterioration in Syrian shelter dwellers.