Nitrogen dioxide Administration, Inhalation 1 Air pollution 1 Article 1 COVID-19 1 COVID-19 Vaccines 1 Carbon monoxide 1 Cluster analysis 1 Electric NO generator 1 Humans 1 Klebsiella pneumoniae 1 Methemoglobin 1 Nitric Oxide 1 Nitric oxide 1 Oxygen Saturation 1 Ozone 1 Particulate matter 10 1 Pilot Projects 1 Pulmonary vasodilator 1 SARS-CoV-2 1 Spontaneous breathing 1 Sulphur dioxide 1 Temporal variation 1 adult 1 airflow 1 arterial pressure 1 artificial ventilation 1 breathing pattern 1 calcium hydroxide 1 chemiluminescence immunoassay 1