Which measurement methods are used for PM mass concentration?

• A. Chemiluminescence.
• B. Beta-attenuation or TEOM.
• C. UV photometry.
• D. Infrared spectroscopy.

Answer: (B)

Measuring PM mass concentration relies on methods that quantify the actual mass of particles collected or weighed. Beta-attenuation and TEOM fit this because they directly relate the amount of particulate matter to a measurable change: beta-attenuation uses how much beta radiation is absorbed by particles on a filter, so more mass means more attenuation; TEOM (tapered element oscillating microbalance) directly weighs the collected particulates by tracking changes in the oscillator’s frequency as mass accumulates. These are standard approaches for obtaining PM mass concentration, often in near real time or continuously.

The other options target gases or rely on optical signals that don’t directly yield PM mass. Chemiluminescence detects NOx gases through light emission, UV photometry Measure gases like ozone or other UV-absorbing species, and infrared spectroscopy identifies or quantifies gases via molecular vibrations—none of these provide PM mass concentration on a filter or via a microbalance.