Effects of Gas and Steam Humidity on Particulate Matter Measurements Obtained Using Light-Scattering Sensors

Abstract

With the increasing need for particulate matter (PM) monitoring, the demand for light-scattering sensors that allow for real-time measurements of PM is increasing. This light-scattering method involves irradiating light to the aerosols in the atmosphere to analyze the scattered light and measure mass concentrations. Humidity affects the measurement results. The humidity in an outdoor environment may exist as gas or steam, such as fog. While the impact of humidity on the light-scattering measurement remains unclear, an accurate estimation of ambient PM concentration is a practical challenge. Therefore, this study investigated the effects of humidity on light-scattering measurements by analyzing the variation in the PM concentration measured by the sensor when relative humidity was due to gaseous and steam vapor. The gaseous humidity did not cause errors in the PM measurements via the light-scattering method. In contrast, steam humidity, such as that caused by fog, resulted in errors in the PM measurement. The results help determine the factors to be considered before applying a light-scattering sensor in an outdoor environment. Based on these factors, directions for technological development can be presented regarding the correction of measurement errors induced by vapor in outdoor environments.

AirMLP: A Multilayer Perceptron Neural Network for Temporal Correction of PM2.5 Values in Turin

“…Previous research has extensively explored the influence of variables such as RH and temperature on sensor performance [46,52,53]. These studies have underscored the pressing need for correction models to rectify inaccuracies in sensor data induced by humidity.…”

System Integration of an Optimally Designed Virtual Impactor with a QCM Sensor as a One-Stop PM2.5 Classification and Detection Platform

“…However, as this method does not directly provide the mass concentration of PM, accurate measurement is impossible. Moreover, the measurement accuracy is easily affected by the PM size, composition, and humidity of the ambient air. , The TEOM method can realize precise measurement of PM mass concentration, but it is generally bulky and expensive and takes a long time for measurement. − The β-attenuation method is used for PM mass measurement based on a correlation between the intensity of the β radiation and the deposited PM mass on a filter. − This method can provide accurate measurements but is subject to interference error and influenced by the dust composition, particle size distribution, and density . In addition, as it uses a radiometric source to emit β particles, it is expensive and bulky.…”

“…Moreover, the measurement accuracy is easily affected by the PM size, composition, and humidity of the ambient air. 26 , 27 The TEOM method can realize precise measurement of PM mass concentration, but it is generally bulky and expensive and takes a long time for measurement. 28 − 30 The β-attenuation method is used for PM mass measurement based on a correlation between the intensity of the β radiation and the deposited PM mass on a filter.…”

Response Surface Modeling of the Steady-State Impedance Responses of Gas Sensor Arrays Comprising Functionalized Carbon Nanotubes to Detect Ozone and Nitrogen Dioxide

“…Optical methods, such as plasmonic optical transmission for ammonia detection [83] and laser scattering for particulate matter (PM) detection [84], have the potential to improve accuracy and stability in environmental sensing. However, miniaturization of optical sensor systems to enable wearability is challenging, and commercially available PM sensors are predominantly handheld.…”