Participants in the new ROCIS virtual cohorts receive a monitoring kit on their doorstep or via mail. The kit includes monitors for particles, carbon monoxide, carbon dioxide, and radon. During the one-month-long cohort, participants monitor their indoor and outdoor air, and receive weekly feedback on their results. Each week, they attend two weekly online ROCIS meetings, with the option of attending in the morning or evening. As usual, all household members are welcome to participate! During the monitoring period, ROCIS participants can test the effectiveness of ROCIS-loaned equipment, including portable air cleaners and DIY filter fans.