Impact of COVID-19 Lockdown Restrictions: Ambient NO2 and Asthma Hospital Admissions.

Aim The World Health Organization (WHO) declared the COVID-19 pandemic a global health emergency. Many countries of the world, including Ireland, closed their borders and imposed nationwide lockdown. During this period, all major anthropogenic transport activities, which contribute to atmospheric pollution, were restricted. The current study examines the impact of the transport restrictions on ambient nitrogen dioxide (NO2) concentrations and hospital admissions for asthma across Ireland. Methods This is a retrospective population-based cohort study. National ambient air quality monitoring network data were analysed to investigation variations in NO2 concentrations. Asthma hospital admissions data were collected from the HSE Hospital In-patient Enquiry (HIPE) for Cork, Dublin, and Meath. Results During the period of transport restrictions, there were reductions in the annual mean NO2 for Cork, Dublin and Meath (i.e. 12µg/m3 to 11µg/m3 (p = 1); 25µg/m3 to 17µg/m3 (p < 0.001); and 23µg/m3 to 21µg/m3 (p = 1)). Reductions in asthma hospital admissions were also observed. Among the 8,471 patient episodes included in this study, the mean [SD] age at admission was 47.2[22.9] years; 61% were female (n=5,134); mean [SD] length of stay was 4.9[10.9] days. Conclusion The findings of this study provide an opportunity to explore the impact of NO2 emissions for Cork, Dublin and Meath on asthma hospital admissions, in order to improve air quality modelling and policy development of management of asthma.