Refined Particulate Matter Measurement in Limburg: A Technological Advancement

Introduction to Grimm EDM Monitors

The Advisory and Research Bureau of the Enforcement and Monitoring Department of the Province of Limburg, known as HMAO, is responsible for measuring particulate matter (PM).
For project-related measurements that require PM data, HMAO currently uses the Grimm EDM 165, a handheld continuous PM monitor. This device is not suitable for long-term use, especially since the pump is not designed for continuous operation. The Grimm EDM 365, however, is suited for this purpose.
In March, a parallel test was conducted with various fine dust monitors. During the measurements, which took place in Maastricht, both their own GRIMM EDM 165 and a GRIMM EDM 365 provided by Ravebo were used. In theory, these monitors should provide comparable values for the different PM fractions, as they undergo the same calibration procedure. However, in practice, there are some differences between these instruments.

Features of the EDM 165

The EDM 165 is a portable spectrometer in a weather-resistant housing. At high relative humidity, the sampled air is diluted with air dried by silica gel in a 1:1 ratio to prevent measuring possible moisture particles due to condensation, and to avoid incorrect results caused by core condensation forming on aerosols. The EDM 165 is highly suitable for short-term online particulate measurements in outdoor environments.

Comparison and Results

The EDM 365 is a stationary spectrometer housed in a weatherproof enclosure. At high relative humidity, a permeation dryer activates to remove water molecules from the incoming air. The EDM 365 is a robust and durable instrument suitable for long-term online PM monitoring.
After over a month of continuous measurement, the hourly averages of both monitors were compared. These results turned out to be very close. Overall, across all PM fractions (PM10, PM2.5, and PM1), the results for the EDM 365 were approximately 6% higher than those of the EDM 165 in this test—an excellent outcome!