Learn: Standards & limits

What is IAQ?

One number for particles: the worse of the PM₂.₅ and PM₁₀ sub-indices, on the same 0–500 scale as the U.S. EPA AQI. It does not include CO₂, VOCs or NOₓ.

Outdoor & weather

AQI vs IAQ: the same scale, two contexts

Both numbers use the same 0–500 color band, but the math is different and so is the answer to "is it bad?"

What to do

WHO vs EPA: two number systems, two philosophies

EPA NAAQS is regulatory. WHO 2021 is aspirational. Terrestream uses the EPA scale; this is how to compare your readings with both.

What to do

ASHRAE ventilation rates: the math behind "open a window"

ASHRAE 62.1 covers commercial; 62.2 covers homes. Both give you a number in CFM per person.

What to do

Health Canada residential guidelines

Canada publishes its own residential indoor air guidelines, one pollutant at a time. The NO₂ limits are much stricter than U.S. outdoor standards; for PM₂.₅ there is no number, only "as low as possible."

What to do

WELL, RESET, LEED: building-level certifications

For commercial buildings, three certifications dominate the indoor-air conversation, and codes such as California's Title 24 set design rules. Each weighs different things, and none of them is conferred by a sensor.

Workplaces & schools

Central-dashboard monitoring for schools, offices, and industry

Many sensors across a building or campus, one workspace, and a queue of the rooms that need attention. A Facilities account adds campus and building views, team roles, room history, and email and text alerts during the coverage hours your team sets.