Nitrogen Dioxide (NO2) Gas Sensor

Nitrogen dioxide is one of the most significant pollutants in urban environments — a direct product of vehicle exhaust, power generation, and industrial combustion. The Sensorbee NO2 Sensor is an electrochemical gas sensor module that detects nitrogen dioxide at concentrations as low as 3 parts per billion, with 1 ppb resolution across a 0–10,000 ppb measurement range. Certified to CEN/TS 17660-1:2022, this 25-gram plug-in module integrates with the Sensorbee Air Pro 2 and Air Lite monitoring platforms to deliver continuous, real-time NO2 data for urban air quality networks, traffic pollution assessments, and environmental compliance monitoring.

How It Works

The NO2 sensor uses electrochemical detection — a proven technology where nitrogen dioxide molecules diffuse through a permeable membrane and react at a working electrode, generating an electrical current proportional to the gas concentration. This electrochemical approach provides the sensitivity needed to measure NO2 at the low parts-per-billion levels that matter for air quality assessment, without the size, cost, or complexity of reference-grade chemiluminescence analysers.

The sensor module measures 55 × 40 × 30 mm and weighs just 25 grams, housed in a polyamide enclosure designed to withstand outdoor exposure from -30 to +40°C. It connects to the Air Pro 2 or Air Lite base station as a plug-in module, where onboard electronics handle signal processing, temperature compensation, and data transmission. No external signal conditioning or calibration hardware is required — the module arrives factory-calibrated and ready for deployment.

Why NO2 Monitoring Matters

Nitrogen dioxide is a regulated pollutant under air quality frameworks worldwide, with ambient concentration limits set to protect public health. At elevated levels, NO2 irritates the respiratory system and contributes to the formation of ground-level ozone and particulate matter. Key sources include:

• Road traffic — diesel engines are the largest source of NO2 in urban areas, making roadside monitoring essential for transport planning and low-emission zone enforcement
• Construction plant — diesel generators, excavators, and site vehicles contribute localised NO2 emissions that may require monitoring under environmental permit conditions
• Industrial combustion — boilers, furnaces, and gas turbines emit NO2 as a combustion byproduct, with emissions limits set by environmental regulators
• Shipping — port areas experience elevated NO2 from vessel engines, particularly during berthing and manoeuvring operations

The 3 ppb limit of detection means the Sensorbee NO2 sensor can resolve the small concentration changes that matter for trend analysis and regulatory assessment — not just detect major pollution events.

Measurement Performance

The NO2 sensor delivers ±7 ppb typical accuracy with 4 ppb repeatability, providing the consistency needed for long-term monitoring campaigns where data comparability between measurement periods is critical. Response time is under 80 seconds, balancing speed with stability for continuous ambient monitoring where one-minute or five-minute averaging periods are standard.

The 0–10,000 ppb measurement range covers all ambient monitoring scenarios, from clean background environments (typically 2–10 ppb) through urban roadside locations (often 20–60 ppb annual mean) to near-source industrial monitoring where short-term peaks may reach several hundred ppb. The 20 ppm guarantee range provides headroom for extreme events without sensor damage.

CEN/TS 17660-1:2022 Compliance

The NO2 sensor's limit of detection is certified to CEN/TS 17660-1:2022, the European technical specification for indicative air quality sensor performance. This standard defines test procedures for evaluating low-cost sensor accuracy, precision, and detection limits under controlled laboratory conditions — providing confidence that the published 3 ppb detection limit reflects real measurement capability, not a theoretical specification.

For monitoring programmes that reference EU air quality directive requirements or need to demonstrate data quality to regulators, CEN/TS 17660-1:2022 certification provides documented evidence of sensor performance.

Integration With Sensorbee Platforms

The NO2 sensor module plugs directly into the Air Pro 2 environmental monitoring station or the Air Lite compact monitor. The base station handles all data acquisition, processing, and transmission — the sensor module itself requires no configuration, power supply, or communication setup.

When deployed with the Air Pro 2, the NO2 sensor can operate alongside other gas sensor modules (SO2, O3, CO, H2S, NO) to create a multi-gas monitoring station capable of measuring the full range of regulated pollutants. Each sensor module operates independently, so adding or replacing individual sensors does not affect other measurements.

Data from the NO2 sensor is transmitted to the Sensorbee Cloud platform via the base station's cellular connection, where it is available for visualisation, analysis, download, and integration with third-party environmental data management systems.

Deployment and Maintenance

The NO2 sensor module is designed for straightforward field deployment. Insert the module into an available sensor port on the Air Pro 2 or Air Lite, and the base station automatically recognises and begins polling the sensor. No tools, wiring, or software configuration are required for installation.

The sensor has an operational life exceeding one year under continuous monitoring conditions. When replacement is needed, the old module is removed and a new factory-calibrated module inserted — a process that takes under two minutes and requires no site recalibration. This plug-and-play replacement model keeps maintenance costs low and minimises data gaps during sensor changes.

Applications

• Urban air quality monitoring — deploy across city networks to map NO2 concentrations, identify pollution hotspots, and track the effectiveness of traffic management and emission reduction measures
• Roadside and traffic monitoring — measure NO2 at kerbside and near-road locations to assess population exposure along major transport corridors and within low-emission zones
• Construction site boundary monitoring — continuous NO2 measurement at site boundaries to demonstrate compliance with environmental permit conditions and manage community impact from diesel plant emissions
• Port and maritime monitoring — track vessel-related NO2 emissions at port facilities, supporting environmental reporting and compliance with maritime emission regulations
• Industrial perimeter monitoring — measure NO2 dispersion from combustion sources at facility boundaries to verify air quality impact on surrounding areas
• Environmental research — high-resolution NO2 data for atmospheric chemistry studies, source apportionment research, and exposure assessment campaigns

Frequently Asked Questions

Can I measure total NOx with this sensor?

The NO2 sensor measures nitrogen dioxide only. To calculate total NOx (NO + NO2), pair this module with the Sensorbee NO sensor (SB4242) on the same base station. The Sensorbee Cloud can then compute and display total NOx values from the combined measurements.

How does this compare to reference-grade analysers?

Reference-grade chemiluminescence analysers offer higher accuracy and are required for official compliance monitoring at designated monitoring stations. The Sensorbee NO2 sensor is designed for indicative monitoring — providing dense spatial coverage across many locations at a fraction of the cost per measurement point, with CEN/TS 17660-1:2022 certified performance.

Does the sensor require field calibration?

Each NO2 sensor module is factory-calibrated before shipment. Field calibration is not required for standard deployment. For monitoring programmes that require traceable calibration verification, the Air Pro 2 base station supports co-location comparison with reference instruments.

What happens in high-humidity conditions?

The electrochemical sensor operates within 15–85% RH. Sensorbee monitoring platforms include environmental conditioning to manage humidity effects on gas sensor performance, maintaining measurement accuracy across varying weather conditions.

How often does the sensor need replacing?

The NO2 sensor has an operational life exceeding one year under continuous monitoring. Plan for annual sensor replacement to maintain measurement performance, with the exact timing depending on environmental conditions and exposure levels at each deployment location.