With the rapid increase of car ownership throughout the country, the pollutant discharge has also increased continuously, and the impact on the environment has become increasingly serious, which has brought great pressure on the air quality in cities and regions. The particulates directly emitted by automobiles, as well as secondary particles formed by the reaction of nitrogen oxides and hydrocarbons emitted from the vehicles, are all components of PM2.5 in the ambient air; at the same time, nitrogen oxides and hydrocarbons are also important for the formation of ozone. Physical things.

Recently, the Ministry of Environmental Protection issued an announcement to solicit opinions on the “Limits and Measurement Methods for Light-duty Vehicle Pollutants (China's Fifth Stage)” (second draft for comment). This standard applies to new vehicle type approval, production consistency check and in-use compliance inspection, including the requirements for light vehicle air pollutant emission control, namely exhaust gas, evaporation and crankcase pollutant emission limits and measurement methods At the same time, it also stipulates the durability of pollution control devices, the technical requirements and measurement methods of on-board diagnostics (OBD) systems.

The standard air pollutant control project includes: carbon monoxide (CO), hydrocarbons (THC), non-methane hydrocarbons (NMHC), nitrogen oxides (NOx), particulate matter (PM), and the need to measure the number of particles of particulate matter (PN ).