How do Particulate Monitors work?
Particulate monitors use several physical principles. Beta attenuation monitors deposit particles on a filter tape and measure the attenuation of beta radiation from a carbon-14 source, which is proportional to deposited mass. Tapered element oscillating microbalance instruments weigh particles continuously on a filter mounted on an oscillating element whose frequency falls as mass accumulates. Optical monitors measure light scattered by particles at one or more angles and convert the signal to mass using an assumed or calibrated factor. High-volume samplers draw air through a size-selective inlet and a pre-weighed filter, giving a gravimetric result that serves as a reference. Condensation particle counters grow ultrafine particles in a supersaturated vapour and count them optically. Size-selective inlets such as cyclones or impactors define the cut point.
Which Particulate Monitors variants are available?
- Beta Attenuation Mass Monitor — A continuous monitor that measures PM mass by the attenuation of beta radiation through dust collected on a filter tape.
- TEOM Particulate Monitor — A continuous monitor that weighs particles on a filter mounted on an oscillating element to give near-real-time PM mass.
- Optical Light-Scattering Dust Monitor — A compact monitor that estimates dust concentration from the light scattered by airborne particles.
- High-Volume PM10 Air Sampler — A gravimetric sampler that draws air through a size-selective inlet and a pre-weighed filter at high flow.
- Condensation Particle Counter — An instrument that grows ultrafine particles in a supersaturated vapour and counts them optically.
How do I choose the right variant?
Choose the monitor by the metric and the purpose. For regulatory PM10 and PM2.5 mass data, beta attenuation or TEOM instruments approved under US EPA or EN methods are used, with gravimetric samplers for reference and auditing. For worker exposure, indoor checks and network densification, low-cost optical monitors give fast indicative results but need correction against reference data. Consider the size cut point, measurement range, averaging time and whether the instrument reports mass or number. Evaluate sampling inlet conditioning, since relative humidity above about 60 percent can bias optical and beta readings through particle growth, so heated inlets or naffion dryers are often fitted. Confirm filter or tape consumption and the calibration and audit schedule.
Where are Particulate Monitors used?
Particulate Monitors are specified in ambient PM10 and PM2.5 monitoring networks, industrial fence-line dust monitoring, indoor and occupational dust exposure checks and ultrafine particle research.
Which standards and certifications apply?
Work with Particulate Monitors is commonly governed by EN 12341, US EPA 40 CFR Part 50 Appendix L, ISO 23210, ISO 10155, HJ 653 and GB 3095. Instrument certifications such as CE marking are confirmed per configuration and never assumed.
What are the key considerations before purchase?
Site the monitor so the inlet is 2 to 15 m above ground, away from walls, vents and trees that distort airflow, and record the inlet height. For beta attenuation and TEOM instruments, replace filter tape or cartridges on schedule and perform leak checks and flow audits with a primary standard. Keep the heated inlet and drying system working, since moisture control is critical to accuracy. For gravimetric samplers, equilibrate filters in a controlled weighing room at 20 to 23 °C and 30 to 40 percent relative humidity before and after sampling. Log operational status and invalid data flags, and co-locate new instruments with a reference monitor for field comparison before reporting.
