Which statement best describes colorimetric tube characteristics?

• A. Record only at the end of shift.
• B. Use the reaction of an airborne contaminant with a color-producing agent to yield a stain length or color intensity; can be directly read.
• C. Are used only for biological hazards.
• D. Require electronic sensors.

Answer: (B)

Colorimetric tubes work by a chemical reaction between an airborne contaminant and a color-producing reagent inside a glass tube. As air is drawn through the tube, the reaction forms a colored stain whose length along the tube or its color intensity is proportional to the contaminant concentration, and you read the result directly from that stain using a calibration scale on the tube. This provides a quick, direct-read measurement without any electronic sensors and works for many different airborne hazards, not just biological ones. The other statements don’t fit because readings aren’t limited to the end of a shift, they don’t require electronics, and they aren’t restricted to biological hazards.