An Approximation for Metal-Oxide Sensor Calibration for Air Quality Monitoring Using Multivariable Statistical Analysis

Abstract

Good air quality is essential for both human beings and the environment in general. The three most harmful air pollutants are nitrogen dioxide (NO2), ozone (O3) and particulate matter. Due to the high cost of monitoring stations, few examples of this type of infrastructure exist, and the use of low-cost sensors could help in air quality monitoring. The cost of metal-oxide sensors (MOS) is usually below EUR 10 and they maintain small dimensions, but their use in air quality monitoring is only valid through an exhaustive calibration process and subsequent precision analysis. We present an on-field calibration technique, based on the least squares method, to fit regression models for low-cost MOS sensors, one that has two main advantages: it can be easily applied by non-expert operators, and it can be used even with only a small amount of calibration data. In addition, the proposed method is adaptive, and the calibration can be refined as more data becomes available. We apply and evaluate the technique with a real dataset from a particular area in the south of Spain (Granada city). The evaluation results show that, despite the simplicity of the technique and the low quantity of data, the accuracy obtained with the low-cost MOS sensors is high enough to be used for air quality monitoring.

Optimizing Urban Air Pollution Detection Systems

“…This assumption is widely used in a variety of situations [48,49], including air pollution monitoring [40,50]. An experimental evaluation of the respective capabilities of the air sensors was also carried out [51,52]. Moreover, in Section 3, we discussed how to calculate this probability in a very general situation, and secondly, we assumed this flow of mobile sensors (vehicles) to the zone of interest to be Poisson.…”

Development and Field Validation of Low-Cost Metal Oxide Nanosensors for Tropospheric Ozone Monitoring in Rural Areas

“…Table 1 shows the concentration range of the target gases covered by the sensors and their rated power, as reported by the manufacturers. In the past, these sensors have been used to monitor air quality in urban areas for different purposes [52][53][54][55]57,58].…”

“…For each device (CO, CS, and CN), the sensors response was split into two sets (training and test) by randomly selecting 30% of the data for training and the remaining 70% for testing. It is well known that MOS sensors are affected by ambient temperature and humidity and, thus, these parameters were also measured and used as inputs to the model [57,68].…”

Ambient Air Quality Measurement with Low-Cost Optical and Electrochemical Sensors: An Evaluation of Continuous Year-Long Operation

“…Although correlation based on linear regression methods is poor, all the studies cited mention the consistency of concentration trends in averaged periods over several minutes to hours. Similarly, differences between calibrations in controlled laboratory conditions and field measurements of ambient air are commonly described [19][20][21][22][23][24]. Measurements of the combined Cairsens sensors were based on reactions of oxidizing gases, i.e., the sum of present NO 2 , ozone, and interferences.…”