Square footage, volume, room type, layout, and use case
A waiting room, classroom, restroom, gym, lobby, and procedure space all turn the same sensor reading into different operational meaning.
Field dossier / 05 Signals
The same room can mean different things.
A room-health index should understand space, behavior, air, maintenance, and public health context together. CO2 alone is not enough. PM2.5 alone is not enough. A cleaned timestamp alone is not enough.
The useful question is not whether one number is perfect. It is whether the system gives operators a better, privacy-preserving risk context than they had before.
Signal stack
What the room needs to know about itself.
People count, density, dwell time, and utilization
Room risk rises through accumulation: how many people are present, how long they stay, and how recently the space was reset.
Talking, respiratory activity, movement, and crowding
Activity changes particle generation and exposure context. The goal is not to identify people. The goal is to understand room conditions.
CO2, PM2.5, VOCs, humidity, temperature, noise, and outdoor air
Environmental sensors can flag ventilation issues, particles, comfort risk, moisture conditions, and changes in the room's operating state.
Cleaning logs, inspections, tickets, filter status, and verification
Operational history turns a live reading into context: what was done, when, by whom, and whether the room recovered.
Wastewater, respiratory activity, and local outbreak context
Community viral load can raise or lower the meaning of the same room conditions, especially when illness is spreading before individual symptoms are obvious.
Public-health signal sources
Community context is becoming part of building context.
CDC National Wastewater Surveillance System
Tracks community-level wastewater signals for pathogens and can show trends before clinical data is complete.
WastewaterSCAN
A public dashboard tracking wastewater trends for SARS-CoV-2, influenza, RSV, and other targets across participating sites.
CDC Respiratory Illness Data
Clinical, laboratory, emergency department, mortality, and wastewater views that can inform seasonal and outbreak posture.
AirNow
Outdoor smoke and particle events matter indoors because buildings import, filter, recirculate, and leak outdoor air.
Guardrails
What a responsible room-health index should not do.
- It should not diagnose individuals, identify sick people, or turn health risk into personal surveillance.
- It should not pretend wastewater or respiratory-activity signals are precise room-level infection counts.
- It should not hide uncertainty. A useful index should explain which signals drove the score.
- It should not stop at alerting. The value is operational: route work, verify recovery, and learn from patterns.
- It should not treat privacy as a footnote. Privacy-preserving aggregation needs to be part of the design.