Why PM2.5 and NO₂ monitoring matters on data centre construction sites

Data centre construction has accelerated dramatically over the past five years. The sites are large, they operate continuously, and they involve an unusually high density of diesel-powered plant — cranes, generators, piling rigs, and concrete mixers — concentrated in a relatively small area. It is, from an air quality perspective, a challenging environment.

What the measurements show

PM2.5 — fine particulate matter with a diameter of 2.5 micrometres or less — is the primary pollutant of concern on active construction sites. Diesel combustion produces significant quantities of ultrafine particles, and construction activities such as concrete cutting and earthworks add coarser particles that contribute to the total particulate load.

In measurements taken on active hyperscale data centre construction sites, we regularly observe PM2.5 concentrations of 50–150 µg/m³ during peak activity — three to ten times the WHO guideline value of 15 µg/m³ for 24-hour average exposure. Concentrations near diesel generator sets can exceed 200 µg/m³ during extended runs.

NO₂ from diesel combustion is also a concern, particularly in enclosed or semi-enclosed areas such as basement construction zones, underground parking structures, and enclosed MEP plant rooms. We have measured NO₂ concentrations above 200 µg/m³ in these environments — the EU workplace exposure limit is 910 µg/m³ for an eight-hour average, but the WHO recommends no more than 25 µg/m³ for 24-hour average exposure.

What responsible monitoring looks like

Effective monitoring on a data centre construction site typically involves three elements.

First, a site boundary network to measure pollutant concentrations at the perimeter and verify that emissions are not affecting neighbouring properties or triggering regulatory action. Four to eight monitoring points around the site boundary, with continuous PM2.5, NO₂, and CO₂ measurement, is a typical configuration.

Second, targeted monitoring at the highest-risk locations — near generator sets, in basement construction zones, and at the main welfare facilities — to identify specific pollution sources and verify that worker exposure remains within acceptable limits.

Third, real-time alerting. Static monitoring that produces weekly spreadsheet reports is not adequate for managing acute exposure events. Monitoring data should be accessible in real-time, with automated alerts when thresholds are breached, so that site managers can take immediate action — whether that is stopping a particular piece of plant, improving temporary ventilation, or evacuating a confined space.

Connectivity on active construction sites

The practical challenge of deploying continuous monitoring on a large, active construction site is connectivity. Running data cables to temporary monitoring points that will need to be repositioned as construction progresses is impractical.

For primary multi-parameter monitoring stations — measuring PM2.5, NO₂, CO₂, noise, and weather — 4G cellular connectivity is the most robust approach. Each unit connects directly to the data platform over the cellular network using a managed SIM, with no on-site network infrastructure required. A monitoring point can be repositioned in minutes.

For supplementary measurement points where a simpler sensor is sufficient, LoRaWAN wireless sensors can extend site coverage without cabling. A single outdoor gateway with cellular backhaul covers a large site, and all sensors report to the same cloud platform as the primary monitoring stations. This is a practical approach for inner-boundary nodes or additional perimeter points on the largest sites.