TVOC usually means a summed concentration of volatile organic compounds under a defined analytical method. VOC Index is different: Sensirion designed it as a normalized, adaptive indicator of indoor VOC events relative to a recent baseline. It is useful for detecting change, not for naming or quantifying every compound in the room.
A VOC Index rise can come from cleaning products, cooking, solvents, fragrance, off-gassing materials, or other reducing gases. The sensor does not identify benzene, formaldehyde, ethanol, limonene, or any other compound by name. The software layer can infer source likelihood only from timing, co-movement, and context.
That distinction protects the user. A high VOC Index is a reason to ventilate, identify the source, or reduce exposure. It is not a lab report, occupational exposure measurement, or proof that a specific chemical exceeded a regulatory threshold.
That is why Terrestream labels this reading VOC Index, not TVOC. The measurement evidence page uses the same label across its charts.
