Through the delivery of an indoor air quality (IAQ) monitoring project in 20 schools around the UK (pre and post COVID-19 emergence), aimed at understanding the ‘real-world’ effectiveness of air filtering technologies, this paper will demonstrate how the emergence of airborne SARS-CoV-2 fundamentally altered the socio-material assemblage of school IAQ, highlighting its reconfigured relations with human and material practices, social and natural rhythms, and technologies.With a proliferation of IAQ monitoring projects aimed at designating air as ‘COVID safe’, this paper argues for a ‘critical air quality science’ that acknowledges the material significance of IAQ (e.g. transmission of COVID-19) by doing physical air quality science, but also embraces the hybridity (material and cultural / social) and multiplicity of IAQ (Bickerstaff, 2004; Cupples, 2009; Garnett, 2017). To do a critical air quality science, I ‘follow myself’ through the process of doing physical air quality science and employ a ‘near ANT’ (Farías, Blok, & Roberts, 2020) approach to use ANT concepts as a source of questions, problems and inspiration to think through the social and natural of IAQ in a hybrid way (Cupples, 2009). This rich, reflexive, and hybrid view of IAQ science in action reveals the connections that were (re)made in the process of measuring and making IAQ breathable in times of COVID. It is envisaged that this critical air quality science approach can ensure that appropriate socio-material interventions are made whilst ensuring that the reconfiguring of school IAQ does not exacerbate existing air inequalities.