Optical Light-Scattering Dust Monitor

What is the Optical Light-Scattering Dust Monitor?

A compact monitor that estimates dust concentration from the light scattered by airborne particles. It is the right choice for indicative monitoring, indoor surveys and dense networks where many low-cost measurement points are needed.

Overview

The optical dust monitor uses a laser or infrared source and one or more photodetectors to measure light scattered by particles passing through a small sensing volume. Forward or side scatter geometry sets the sensitivity range, and a fan or pump draws sample air through the optics. Because scattered intensity depends on particle size, shape, refractive index and density, the instrument applies a calibration factor or a size-segmented algorithm to report a mass-equivalent concentration. Some models add a size-selective inlet for PM10 or PM2.5 and a humidity sensor to flag conditions where hygroscopic growth biases results. Ranges from 0 to 1000 micrograms per cubic metre with 0.1 resolution suit indoor and outdoor screening. Low power, small size and digital outputs allow solar-powered nodes, and several units co-located with a reference monitor can be corrected for local conditions.

How does it 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.

What are the key features?

• Laser scattering gives fast response for dust trend and hotspot detection.
• Compact low-power housing suits battery or solar-powered network nodes.
• Optional PM10 or PM2.5 inlet defines a size cut point.
• Humidity sensor flags conditions where particle growth biases readings.
• Digital outputs feed cloud dashboards and data platforms directly.
• Co-location correction against a reference monitor improves accuracy.

What are the technical specifications?

A typical optical light-scattering dust monitor configuration offers measurement principle of Laser light scattering (90° or forward), particle size range of 0.3–10 µm, measurement range of 0–1000 µg/m³, resolution of 0.1 µg/m³, sampling interval of 1 s to 1 h, selectable and sample flow rate of 0.5–1.5 L/min. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Optical Light-Scattering Dust Monitor is used in dense urban and industrial monitoring networks, indoor air quality surveys, construction and demolition dust checks and occupational exposure screening. Across the wider Particulate Monitors class, laboratories also deploy it for ambient PM10 and PM2.5 monitoring networks, industrial fence-line dust monitoring and indoor and occupational dust exposure checks.

Which standards and certifications apply?

Relevant standards and methods include EN 12341, US EPA 40 CFR Part 50 Appendix L, ISO 23210, ISO 10155, HJ 653 and GB 3095. Certification candidates for this model are CE, RoHS and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

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.

How do I select the right Optical Light-Scattering Dust Monitor?

Select this monitor for indicative data where cost and coverage matter more than reference accuracy. For compliance reporting, pair it with or replace it by a beta attenuation or TEOM instrument. In an RFQ, state the required size cut, range, output protocol and whether co-location correction is planned.

How does it compare with other Particulate Monitors variants?

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.