Regulatory-grade pollutant concentrations and composite index.
Authoritative sources exist and publish continuously. Adapter not built.
Particulate mass concentration at the monitor.
Concentration at the monitor, on the averaging period the operator publishes.
Gas concentrations at the monitor.
The index derived from the underlying concentrations.
An instrument read a value at a place and a time.
An analyst or a model produced this from other data. It is a product, not a sensor.
Measured at a fixed station. The record discloses which one and how far it is from you.
Published by an authoritative operator of the instrument.
An authoritative body's analytical product. Its uncertainty is the source's own.
Regulatory rather than advisory data — exceedances carry penalties, so the underlying readings are already scrutinised and contested. AQI is derived from concentrations and is a different object from the concentrations themselves.
Not named here yet. Candidate sources for this lane exist and are identified internally, but they have not been verified against the primary documentation — and an unverified source attribution on a public page is the exact mistake this company exists to avoid. They appear here when they have been checked, not before.
A permit exceedance. A toxic tort where exposure at an address on a date is the case. An event cancellation. A worksite closure reviewed after the fact.
That framing is our analysis of where disputes arise, not a claim of fact about any matter.
We are not capturing this lane today, so there is nothing here to sell you and we are not going to pretend otherwise. What we do want is to know what you would actually ask it. Requests decide what gets built next — that is not a courtesy, it is how the order is set.