What does invalid exhaust remote sensing mean?

[IsabellaDella]

Invalid exhaust remote sensing indicates that the vehicle's emissions do not meet the required standards. Exhaust remote sensing is a method used by traffic authorities to monitor 'black smoke vehicles' and non-compliant 'yellow label vehicles' with substandard emissions. Through a system platform, it tracks the actual operational status of various inspection stations, allowing environmental protection departments to utilize big data to derive environmental statistics. The working principle of exhaust remote sensing is as follows: it sends ultraviolet and infrared light from a light source to an optical reflector on the opposite side of the road, which then reflects the light back to a detector. As a vehicle passes through these light beams on the road, its exhaust gases absorb the light, altering the intensity of the transmitted light. By monitoring changes in light intensity within the detector, the system measures the concentration of nitrogen oxides, hydrocarbons, and carbon monoxide emitted by vehicles on the road.