A standard operating procedure was adopted (see Methods), covering 12 activities over ~1 hour, with each activity involving up to 5 repeat actions, with a 30 s pause between each. These activities included breathing, coughing, singing single notes ("/ɑ/") at different pitches, and speaking and singing the "Happy Birthday" song at different volumes. At the beginning of each action, participants stepped forward to the funnel (Fig. ) such that the dorsum of the nose was aligned to the plane of the base of the cone. Participant position relative to the funnel was monitored to ensure consistency (within 10 cm of the sampling tubes) across all measurements (Extended Data Fig. ). As in previous studies, we report concentrations sampled through the collection funnel, which allows comparison of particle emission rates on a relative basis between activities. In reality, particle concentrations will become rapidly diluted once particles are exhaled, leading to strong spatial variations.