| Optical particle sensor | Particles suspended in air; some models report particle counts or estimated PM1, PM2.5, and PM10 concentrations. | A light source illuminates particles passing through a sensing chamber. A photodetector measures scattered light, which the device uses to estimate particle concentration or size distribution. | Can detect increases in airborne aerosol that may occur when someone exhales e-cigarette aerosol. | Provides a direct indication of airborne particles and can support rapid event detection. | Does not identify the particles as vaping aerosol. Dust, smoke, cooking aerosols, and other sources can produce similar readings. Reported PM values are estimates and may not represent the aerosol’s actual mass accurately. | Check response time, airflow requirements, particle-size range, calibration method, and performance under the humidity conditions expected at the installation site. |
| Laser-scattering particle sensor | Light-scattering signals from airborne particles, often used to estimate particle concentration and size categories. | A laser or other focused light source illuminates particles in a controlled optical chamber. The intensity and pattern of scattered light are processed by the sensor electronics. | May provide a useful aerosol-event signal when paired with suitable thresholds and environmental context. | Can offer particle measurements with finer optical detection than some basic particle-sensing designs. | Like other optical particle sensors, it is not vaping-specific. Droplet evaporation, humidity, contamination, and placement can affect readings. | Ask for documentation on detection range, cleaning needs, sampling design, operating temperature and humidity, and the distinction between measured signals and calculated PM estimates. |
| Metal-oxide semiconductor (MOS) gas sensor | Changes in electrical resistance caused by exposure to certain gases or volatile compounds. | A heated sensing material changes its electrical properties when gases interact with its surface. The device converts this change into a signal. | Can register changes in the surrounding gas mixture, but should be treated as a broad gas or VOC indicator rather than a nicotine-specific detector. | Compact and suitable for monitoring general changes in air composition. | Responses may be affected by temperature, humidity, sensor aging, and interfering gases. A signal alone cannot reliably identify vaping or a particular compound. | Review the stated target gases, cross-sensitivity information, warm-up requirements, calibration guidance, and expected replacement interval. |
| Photoionization detector (PID) | Ionizable volatile organic compounds (VOCs), reported as an aggregate response rather than as identification of each compound. | Ultraviolet light ionizes certain gas molecules. The resulting ions create a small electrical current that is measured by the instrument. | May detect some VOC changes in air, but is not a definitive vaping detector and does not identify nicotine by itself. | Useful for broad VOC monitoring in applications where the target compounds are within the instrument’s response range. | Not all compounds are detectable by a given lamp energy. Humidity and other gases can influence readings, and a PID reading does not establish the source of a VOC signal. | Confirm lamp energy, detection range, calibration gas, humidity performance, maintenance requirements, and whether the intended compounds fall within the device’s capabilities. |
| Temperature and relative-humidity sensor | Ambient temperature and relative humidity. | Electronic sensing elements change their electrical properties in response to temperature or moisture in the air. | Provides environmental context that can help interpret particle and gas-sensor readings; it does not detect vaping on its own. | Can help flag conditions that may affect sensor readings and support environmental compensation. | Cannot distinguish vaping from other aerosol or gas sources. | Check accuracy, operating range, placement, condensation resistance, and whether the monitoring system uses these readings to qualify other sensor data. |
| Carbon dioxide (CO₂) sensor | Carbon dioxide concentration in air. | Many indoor-air models use non-dispersive infrared (NDIR) measurement: CO₂ absorbs infrared light at characteristic wavelengths, and the sensor estimates concentration from the absorption. | CO₂ is not a reliable direct indicator of vaping. It may provide separate occupancy or ventilation context in an indoor monitoring system. | Useful for assessing ventilation and occupancy-related air-quality conditions when properly installed. | Vaping aerosols cannot be identified from a CO₂ reading. Occupancy, ventilation, and other sources influence CO₂ levels. | Do not use CO₂ as the sole vaping-detection input. Verify measurement range, calibration approach, installation height, and ventilation-related use case. |
| Multi-sensor detection system | A combination of particle, gas, temperature, humidity, and sometimes occupancy or event data. | Software combines signals from multiple sensing elements and applies thresholds, timing rules, or classification logic to identify patterns of interest. | Combining independent signals may improve contextual interpretation compared with relying on a single sensor, but it does not guarantee source identification. | Can reduce reliance on one measurement and provide more information for evaluating potential events. | Performance depends on sensor placement, calibration, algorithms, local conditions, and validation against representative real-world events. False alarms remain possible. | Request documented test conditions, event and false-alarm metrics, data-handling details, integration interfaces, calibration procedures, and ongoing maintenance requirements. |