COVID-19 transport restrictions in Ireland: impact on air quality and respiratory hospital admissions

AIM: Exposure to poor air quality is a well-established factor for exacerbation of respiratory system diseases (RSDs); whether air pollutants are a cause of the development of RSD, however, remains unclear. This study aimed to examine the relationship between COVID-19 transport restrictions and hospital admissions because of RSD in Dublin city and county for 2020. STUDY DESIGN: This was a retrospective population-based cohort. METHODS: Admission data were collected from the Health Service Executive Hospital In-patient Enquiry. Daily count of hospital admissions with Dublin city and county address with primary diagnosis of RSD was performed. The daily air nitrogen dioxide (NO(2)) data were obtained from the Environmental Protection Agency (EPA). RESULTS: During the period of transport restrictions, there was a reduction in the annual mean NO(2) from 25 μg/m(3) to 17 μg/m(3) (P < 0.001), and decreases in hospital admissions for RSD were observed. Among the 9934 patient episodes included in this study, the mean age at admission was 61.5 years, 57.8% were female (n = 5744), and mean (standard deviation) length of stay was 7.5 (13.52) days. CONCLUSION: This study, using routinely gathered data, suggests that decreases in ambient NO(2) as related to COVID-19 transport restrictions were significantly associated with lower asthma and chronic obstructive pulmonary disease admissions.