EU Science Hub

Review of sensors for air quality monitoring

Abstract: 

A growing number of companies started commercialising low-cost sensors (LCS) that are said to be able to monitor air pollution in outdoor air. The benefit about the use of LCS is the increased spatial coverage when monitoring air quality in cities and remote locations. Today, there are hundreds of LCSs commercially available on the market with a cost ranging from a few hundred to a few thousand euro. At the same time, independent information about the performance of sensor systems against reference measurements is only available for about 110 sensor systems in literature. In fact, the data quality of low-cost sensors is often questionable. It is affected by atmospheric conditions, pollutant concentration levels and therefore by the site location where the measurements are carried out. This report presents the results of quantitative studies the performance of tested low-cost sensors against reference measurement are collected. The information collected was an attempt to assess the following issues: • Agreement between sensor and reference measurements • Availability of raw data, transparency of data treatment and possibility of a-posteriori calibration • Capability to measure multiple pollutants • Affordability of sensor systems taking into consideration the number of provided sensors This information gathered in this report comes from research institutes having a LCS testing program in place, e.g. the California Board - Air Quality Sensor Performance Evaluation Center (AQ-SPEC), the European Union Joint Research Centre (EU JRC) and the United States Environmental Protection Agency (US EPA). Other information was drawn from peer-reviewed journals that tested different types of sensors in research studies. Finally, this information has been linked with scripts able to perform a statistical analysis in the form of an electronic report. This work represents an important review to classify all commercial sensors based on their agreement with reference systems. There are only a few available commercial sensor systems that are consistent with all issues mentioned above that show a good agreement with reference measurements (coefficient of determination, R², higher than 0.75 and slope of regression line within 1±0.5) and total price lower than 3 k€. In conclusion to this market analysis, the only sensor system satisfying the requirements of multipollutant, availability of raw data, transparency of all applied data treatment, availability of evaluation of the performance of sensor system in literature with high coefficient of determination (>0.85) has been found to be the AirSensEUR v.2.