Perimeter Air and Fenceline Monitoring

Perimeter air monitoring is the continuous measurement of dust, particulate matter, and gases at the boundary of a construction site, industrial facility, or other active job site. It documents whether work on site is affecting air quality at the boundary and in the community beyond it: the record that permit conditions, a DER-10 Community Air Monitoring Plan, or a local dust rule asks for.

Both mean continuous monitoring at the boundary of a site, and the terms are often used interchangeably. Fenceline monitoring is the usual term at refineries and chemical plants, where EPA rules prescribe it: at refineries under 40 CFR 63 Subpart CC with passive benzene samplers (EPA Method 325A/B), and at chemical plants under the 2024 HON rule. Perimeter monitoring is the usual term in construction. Aethair PRO serves both.

Aethair PRO measures PM1, PM2.5, PM10, and total PM continuously at the boundary, with gas sensor cartridges for VOCs or a specific gas. Readings stream over 4G LTE to Environet, where a reading above a trigger level raises an alert, and Aethair Reports writes the perimeter report from the same data.

Yes. Thiamis brings third-party instruments (weather stations, dust monitors such as the TSI DustTrak, noise meters, and gas analyzers) into the platform. The equipment keeps running, and its readings appear in Environet next to the Aethair PRO's, with the same alerts and reports.

It depends on the site: the trigger levels in its permit or planning conditions, a New York DER-10 Community Air Monitoring Plan (PM10 more than 100 µg/m³ above upwind over 15 minutes calls for dust suppression), and local agency rules. The NAAQS PM2.5 values (9 µg/m³ annual, 35 µg/m³ 24-hour) are used as reference values. Worker silica exposure is judged against the OSHA limit of 50 µg/m³, measured by personal sampling rather than at the fence. Aethair Reports applies the levels you configure to the readings.

Aethair PRO ships calibrated, reports over its own 4G LTE, and can run on solar power with the Solar Panel Bracket, so deployment is mount and power on: there is no site network to join, and the readings appear in Environet as soon as it is running.

Yes. Every reading is time-stamped and kept in the continuous record. Aethair Reports produces the perimeter report from it (site map, impact assessment with alert-level events and wind, and the data table) on demand or on a schedule for regulators, agencies, or clients.

There is no single universal figure. Dust limits are usually set as local trigger and action levels in the site's permit conditions, expressed as PM10 (and sometimes total dust) concentrations at the boundary. Real-time monitoring against a trigger level set below the hard limit is what lets a site act before it breaches.

Because it answers the question that always follows a dust spike: was it us? When an exceedance coincides with wind blowing from the working area toward the monitor, the dust is attributable to the site; a spike with wind from the opposite direction points to an external source. Without wind data, boundary dust readings are hard to defend.

Yes, where concrete, stone, or masonry is cut or ground. Respirable crystalline silica is a specific, strictly limited health hazard that a general dust reading cannot quantify. It requires size-selective, crystalline-specific gravimetric sampling for worker-exposure compliance, alongside real-time respirable-dust monitoring for control.

A boundary station combining real-time PM10, PM2.5, and total dust with noise (Leq) and wind speed and direction, alerting against local trigger levels. Add respirable-silica sampling where relevant. Use the configurator to build and customize the configuration for your site.