This article starts from "histoire croisée" to develop a genuinely relational analysis of performances of health education in the context of open-air schools. It interrogates, through places, people, and things conceived of as being performatively entangled, the notion of an internationalisation of school hygiene. These places, people, and things -- "international" conferences and exhibitions, "figureheads" of the aspiring New Schools and open-air schools movements, and printed, photographed, and designed materials -- reveal open-air schools as "practice[s] and movement[s]" unbound by national or otherwise (real-)imagined borders. Fragmentation accompanied their circulation and ensued from their co-constitutive role in the mediation of knowledge and praxis around hygiene. While still underexplored, economic factors were key to this process. Their analysis from within the "meshwork" in which non-/humans were (are) entangled opens up new lines of enquiry.