Conflicts of interest: S. Mailhot-Larouche has no potential conflicts of interest to disclose. J. Busby reports grant funding from AstraZeneca, paid to his institution. S. Couillard reports unrestricted research grants from the NIHR Oxford BRC, the Quebec Respiratory Health Research Network, the Association Pulmonaire du Québec, the Academy of Medical Sciences, AstraZeneca, bioMérieux, Circassia Niox Group and Sanofi-Genyme-Regeneron, speaker honoraria from AstraZeneca, GlaxoSmithKline, Sanofi–Regeneron and Valeo Pharma, consultancy fees from FirstThought, AstraZeneca, GlaxoSmithKline, Sanofi–Regeneron, Access Biotechnology and Access Industries, and sponsorship to attend/speak at international scientific meetings by/for AstraZeneca and Sanofi–Regeneron; S. Couillard is also an advisory board member for and retains stock options with Biometry Inc – a company which is developing a FeNO device (myBiometry), advised the Institut national d'excellence en santé et services sociaux (INESSS) for an update of the asthma general practice information booklet for general practitioners, is a member of the asthma steering committee of the Canadian Thoracic Society, is the holder of the Association Pulmonaire du Québec's Research Chair in Respiratory medicine and is a Clinical research scholar of the Fonds de recherche du Québec.