EC (electrochemical): a sensor type that measures gaseous pollutants. Please click here to learn more about the details of its operational principle.

FEM (Federal Equivalent Method): a method for ambient air monitoring that has been designated as an equivalent method to the Federal Reference Method in accordance with Title 40, Part 53 of the Code of Federal Regulations (40 CFR Part 53).

Gas: gaseous pollutants including carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO₂), nitogen oxides (NO_x), ozone (O₃), total volatile organic compounds (tVOC).

MAE (Mean Absolute Error): is the absolute difference between the sensors and the reference instruments. The larger MAE values, the higher measurement errors as compared to the reference instruments.

MOx (metal oxide): a sensor type used to measure gaseous pollutants. Please click here to learn more about the details of its operational principle.

PID (photoionization detection): a sensor type used to measure gaseous pollutants. This sensor uses a high energy lamp to break apart gas molecules into charged particles that will land on a detector to create an electrical current.

PM (particulate matter): particle pollutants including PM₁, PM_2.5, PM₁₀, ultrafine particle (UFP), black carbon (BC).

ppb (parts per billion): a unit measurement to express concentrations of gas pollutants in air.

R² (R-squared; coefficient of determination): a statistical parameter measuring the degree of relation between two variables. Here, it measures the linear relationship between the sensor and the reference instrument. An R2 approaching the value of 1 reflects a near perfect correlation, whereas a value of 0 indicates a complete lack of correlation.

μg/m³ (micrograms per meter cubed): a unit of measurement for particles to express micrograms of particulate pollutant per cubic meter of air.

UV (ultra-violet): a sensor type used to measure gaseous pollutants. This sensor uses a high energy lamp to emit high frequency light which is absorbed by certain gases. The level of absorption is related to the concentration of that gas.

     

All documents, reports, data, and other information provided on this website are for informational and/or educational use only. Some sensors evaluated by AQ-SPEC were field-tested inside a custom-made aluminum enclosure to protect the sensors from windblown rain, harsh sunlight, and animals. The field evaluation reports on this website contain data collected at an monitoring station during a specific 30- to 60-day period and cannot be duplicated at a different location, season, or time period. As sensor performance may be affected by time- and location-specific environmental conditions at the test site, replication and/or duplication of results may not possible to achieve. Lab evaluations were conducted in one of AQ-SPEC’s two environmental chambers with pollutant and interferent concentrations that were generated from nebulizer solutions, dust dispensers, and gas dilution calibrators. Lab environments may not be able to fully replicate the conditions experienced under ambient settings. The sensor assembly, installation, and use can also impact the performance of products evaluated by AQ-SPEC. South Coast Air Quality Management District (South Coast AQMD) makes no claim, warranty, or guarantee that these devices will or will not work when operated by other users for their specific applications.

South Coast AQMD's AQ-SPEC aims at providing information to and for the benefit of the public to make informed purchasing decisions on air quality sensors. In accordance with this mission, the general policy of the Governing Board of the Agency is to exclude from the AQ-SPEC website all commercial advertising and promotional material, including links which provide exclusive private or financial benefit to commercial, non-public enterprises and which do not promote or enhance a public benefit to the general public. As a Government Agency, the South Coast AQMD neither endorses nor supports individual private commercial enterprises through display of their products on the AQ-SPEC website or through providing links to the sites of such commercial enterprises.