Belgium – Halle, May 25th 2026 – To evaluate long-term sensor stability and atmospheric trends, two of our environmental wearables were deployed for continuous air quality monitoring in Halle, located 15 km south of Brussels. Over the preceding weeks, both devices demonstrated reliable baseline tracking, yielding measurements that correlated with official reference data from the IRCELine measurement stations.
On May 25th, at approximately noon, a major industrial fire broke out at a textile processing facility in the neighboring city of Tubize. Heavy smoke plumes were reported as visible as far north as the Brussels Airport, and stagnant, low-wind conditions caused the emissions to disperse across all adjacent municipalities. Operating actively during this period, our deployed wearables captured the localized increase in pollution originating from the incident.
Indicative pollutants
Meteorological conditions in Belgium had remained stable since the week preceding the incident, characterized by clear, sunny skies and ambient temperatures peaking at 30°C. This steady baseline was clearly reflected in our background sensor measurements. However, despite the high thermal buoyancy which drove the smoke plume high into the atmosphere and initially carried the bulk of the coarse particulate matter away from ground-level infrastructure, our wearables detected a pronounced spike in gaseous pollutants. The devices captured a significant increase in nitrogen dioxide (NO2) concentrations.
Concurrently, the volatile organic compounds (VOC) sensor recorded a sharp response to the plume. This pronounced shift in the VOC baseline was driven by competing reactions on the sensor’s metal-oxide surface, triggered by the simultaneous presence of reducing gases (such as sulfur dioxide, SO2) and oxidizing gases (NO2).
Aside from the sharp increases in VOC and NO2 concentrations, a slight elevation in carbon monoxide (CO) levels was also recorded during the incident.
Sensor Calibration
Further data analysis will be carried out to refine the raw sensor readings and map them to precise, absolute concentration values. This post-calibration process will be executed by cross-referencing our data with the reference-grade pollutant concentration baselines available from the official IRCELine monitoring network.