What does National III and National IV emission standards mean?

[Peter]

National III and National IV refer to exhaust emission standards. National III emission standard is the abbreviation for the third-stage national motor vehicle pollutant emission standard, while National IV emission standard is the abbreviation for the fourth-stage national motor vehicle pollutant emission standard. Compared to National III, National IV requires light-duty vehicles to reduce single-vehicle pollutant emissions by approximately 50%, heavy-duty vehicles to reduce single-vehicle emissions by about 30%, and particulate matter emissions by more than 80%. Automobile emission pollutants mainly include hydrocarbons, nitrogen oxides, carbon monoxide, and particulate matter. The National IV standard achieves control and reduction of vehicle emissions below specified levels through the application of technologies such as improved catalytic converter active layers, secondary air injection, and exhaust gas recirculation systems with cooling devices.

[JayceLynn]

I recently researched this topic. The terms 'China III' and 'China IV' refer to vehicle emission standards. The China III standard was mainly implemented between 2007 and 2011, requiring vehicles to keep harmful substances like carbon monoxide and hydrocarbons below certain limits. The China IV standard, introduced around 2011, is even stricter - it reduced pollutant indicators by about 30% compared to China III and added testing requirements for nitrogen oxides and particulate matter. Nowadays during vehicle inspections, China III vehicles often fail due to excessive emissions, and many cities restrict China III diesel vehicles from entering urban areas. My own 2010 model car suffered from this - it failed last year's emission test, costing me nearly 2,000 yuan to fix.

[Corey]

I remember the China IV emission standard was an upgraded environmental requirement following China III. Simply put, it's a stricter tailpipe emission regulation imposed by the government on automakers to improve air quality. The China III standard limited carbon monoxide emissions to no more than 2.3 grams per kilometer, while China IV directly reduced it to 1.0 grams. More crucially, China IV mandated the installation of OBD systems - those self-diagnostic devices in vehicles that illuminate warning lights. Some regions have already begun restricting China III vehicles from roads, like Beijing which completely banned China III diesel trucks within the Fifth Ring Road last year. For regular maintenance, special attention should be paid to the catalytic converter and oxygen sensor, as aging of these two components most easily leads to excessive emissions.

[DiGarrett]

Actually, this is a vehicle environmental protection standard established by the state. China III and China IV represent different stages of emission control levels. China III was implemented around 2007 to 2010, when the exhaust treatment technology for vehicles was still relatively simple. By the China IV standard after 2011, the technology became much more advanced, with the addition of particulate filters and more sophisticated post-processing systems. Nowadays, if you go to the used car market, you'll find that China IV vehicles from the same year are generally several thousand yuan more expensive than China III vehicles, because they pass annual inspections more easily. Some cities' environmental traffic restriction policies also place great importance on this standard.

[LaEvangeline]

I've come across many car owners who don't quite understand this. China III and China IV are essentially two national standard levels for vehicle exhaust emissions. China III primarily controls hydrocarbons and nitrogen oxides, while China IV adds requirements for particulate matter concentration and evaporative pollution. Currently, China III diesel vehicles face restrictions across various regions, with some highways completely off-limits to them. To meet the standards, manufacturers need to improve engine fuel injection systems and catalytic converters. Last year, my friend bought a used China III vehicle, but it failed the annual inspection five times and ultimately had to be sold as scrap metal.

[Gomes]

When it comes to emission standards, China III and China IV represent two different stages of environmental technology. China III was implemented around 2007, requiring gasoline vehicles to emit no more than 0.2 grams of hydrocarbons per kilometer. By the time China IV standards came into effect after 2011, this value was reduced to 0.1 grams, and new requirements for OBD (On-Board Diagnostics) systems were added. Nowadays, many cities impose driving restrictions on China III vehicles, especially during severe smog conditions. I recommend always checking the number of stars on the environmental label when buying a used car—four stars indicate China IV, while three stars mean China III. This difference directly affects the vehicle's operating costs and annual inspection pass rate.