Respiratory dust may cause damage to different parts and degrees of the body after entering the body. According to the Global Burden of Disease Database 2019, the incidence of pneumoconiosis, the number of cases of the disease and the annual absolute value of disability-adjusted life expectancy have been on the rise from 1990 to 2019, both globally and in China. In order to reduce the incidence of occupational pneumoconiosis and the incidence of accidents, controlling the respiratory dust concentration in the working environment is regarded as an effective means of disposal, and therefore regular monitoring of the amount of dust picked up by the workers is a necessary way of preventing the occurrence of pneumoconiosis. The traditional dust measurement to determine the total dust concentration in the air of the production environment adopts the monitoring method of instantaneous fixed-point sampling. Although these instruments have achieved accurate monitoring and are real-time instruments calibrated by the manufacturer, they cannot be used for individual exposure monitoring because they are expensive, not easy to carry, and cannot monitor the respiratory dust concentration inhaled by an individual worker throughout the working time, thus they cannot reflect the real dust exposure of the workers, and the results have certain limitations. In contrast, individual monitoring techniques are considered to be the best method for assessing individual particulate exposure levels. Since the 1970s, Europe and the United States have begun to pay attention to the research of individual exposure monitoring technology. With the advancement of optoelectronic information and science technology, cheaper electronic panels and smaller light scattering sensors have been developed, gradually solving the cost problem and achieving the goal of improving the spatial and temporal resolution of particulate matter concentration monitoring.
This report is based on the Monte Carlo simulation of particle size, scattering-light wavelength, refractive index and other parameters involved in the measurement of particulate matter concentration in the different scattering angle of the scattered light intensity changes simulation calculations, through the comparison of the final result of less interference factors, can be used as a follow-up experimental parameter of the incident light wavelength and scattering angle values. The calculation results concluded that the light source of 650nm and scattering angle of 90°should be selected as the subsequent monitoring parameters. Based on the above results, the specific construction of the low-cost sensor is processed. When outside air passes through the light test chamber, particles in the sample air scatter the light beam. This scattering is then captured by a photoelectric acquisition unit, which converts the scattered light signals into voltage pulse signals. These signals are then amplified, converted to digital form, and then quantized into digital signals. By adopting the index standard set by EPA, selecting the sensor with the principle of β-ray method as the reference instrument and the low-cost sensor as the test instrument, constructing the low-cost sensor dust monitoring system for on-site monitoring, analyzing and processing the reported data and comparing them with the EPA standard, the R² all reached more than 0.8, and the NRMSE was lower than 30%, and this result indicates that the monitoring data meets the standard that the Low-cost sensors have some accuracy. The reliability of low-cost sensor data can expand the understanding of pollutant trends in space and time, as well as provide information for personal exposure and emission inventory studies, which has far-reaching implications for environmental monitoring.
 

low-cost sensor ; PM ; light scattering