Fig. 1. Principle of backward light scattering

Fig. 2. Image of scattered spot

Fig. 3. Flow chart of image processing

Fig. 4. Photograph of portable measuring device for fugitive-dust-emission particulate

Fig. 5. Typical image of backward light scattering of particulate

Fig. 6. Fitting curve of concentration and relative gray value

Fig. 7. Corrected gray value as a function of measuring distance

Fig. 8. Calibration curve of measuring distance

Fig. 9. Relative error of mass concentration of particulates as a function of distance resolution

Fig. 10. Particle size as a function of scattered light intensity

Fig. 11. Measurement results of mass concentration and relative error

Fig. 12. Collected images. (a) Image of scattered spot of fugitive-dust-emission particulate; (b) image of background

Fig. 13. Measurement results of mass concentration for fugitive dust emission