Technicians at the Delta Air Observatory’s calibration centre in Ismailia walked off the job on Friday, 16 October, after demanding checks on sensor components used at monitoring stations from Cairo to the Nile Delta. Their strike has stopped routine validation and brought a fierce scientific dispute into public view: researchers say a screening test found suspect modules at 31 of the network’s 58 stations.
The observatory says the parts have not been proved to affect readings and that its published pollution figures remain fit for use. The technicians’ action forced managers to suspend new data certification on Saturday, while a team from a Cairo university began testing retained modules. Results could affect health research, environmental planning and the credibility of Egypt’s air-quality record.
A test built for sensors
The dispute began when technicians used a handheld verifier, called DustMark, to compare the electronic fingerprints of installed sensor modules with a reference catalogue. The device was developed after calibration staff complained that parts bought as replacements could not be traced to a verified manufacturer. They say 31 modules returned inconsistent signatures; the observatory has not released the full test results.
Fermin Watsica, a calibration technician who joined the strike, said staff had raised concerns for months. “We could not keep stamping readings as sound when the parts themselves had not been checked,” he said. The stoppage involves 74 technicians, who are seeking a public register of approved components and a review of measurements collected since 2022.
We could not keep stamping readings as sound when the parts themselves had not been checked.
Fermin Watsica, calibration technician
The observatory’s research director, Norene Torphy, said DustMark was a screening tool, not a scientific verdict. “A mismatched fingerprint can mean a different production batch, a replacement board or a faulty component. It does not, by itself, prove that a station reported false pollution levels,” she said. The agency says it is testing modules against laboratory instruments before deciding whether to revise its data.
Readings under scrutiny
A preliminary comparison by researchers at the fictional Cairo Institute for Atmospheric Studies found that 12 of 18 modules they tested responded more slowly to changes in fine-particle concentration than the reference units. The team has not established how much that lag affected station records. Its lead scientist, Benė Antanina, said the gap was large enough to warrant rechecking daily averages during dust episodes.
The observatory’s network helps researchers track fine particles, which can pass deep into the lungs, and informs decisions on transport and industrial emissions. The system cost 48 million Egyptian pounds (about €900,000) to expand and maintain, according to its latest budget summary. Researchers warned that rewriting past measurements without a clear method could be as damaging as leaving faulty readings untouched.
The observatory says it will keep stations operating but mark data from the disputed modules as provisional. Technicians have rejected a partial return to work unless a testing schedule and outside review are agreed in writing. Their union representative, Umesh Dubey, said the strike could end this week if the agency publishes the component catalogue and allows workers to observe the checks.
The Cairo institute expects to publish its first comparison results by 2 November. Until then, scientists say city-level pollution rankings and studies using the contested readings should be treated cautiously. The observatory has promised to issue a station-by-station account once the tests are complete, but has not said whether it will recalculate earlier annual figures.
