Vehicle emissions are a major source of air pollution, and understanding the different types of emissions is key to reducing their impact. There are three main types of automotive emissions: evaporative emissions, refueling losses, and exhaust emissions. It's important to note that vehicles can emit pollutants even when they're not running. Gasoline, diesel, and E85-powered cars, SUVs, and light vans all emit greenhouse gases and smog-forming pollutants from their tailpipes.
Stricter European standards have accelerated the introduction of greener vehicle technologies. By understanding the harmful emissions that come from car exhausts, people can play a more active role in reducing pollution from vehicle traffic. The transient test procedure for heavy-duty vehicles combines two philosophies: the cycle is randomly composed from real driving cycle data, and vehicle prototype certification tests for 50,000 miles of use are based on the 40.7 mile durability cycle of the Automobile Manufacturers Association (AMA). Methanol-powered vehicles have higher formaldehyde emissions than those powered by diesel or gasoline with catalysts.
In contrast, ultra-low-emission vehicles count as “super credits” that can be used to reduce total manufacturers' emissions. Heavy-duty vehicles powered by gasoline have seen a significant reduction in HC, CO, and NOx emissions since the imposition of standards. The recognition of motor vehicles as a major source of pollutants has been extended to other countries, many of which have imposed various standards and test procedures that reflect varying degrees of stringency. The main objective of these programs is to determine the extent to which fuel economy, exhaust emissions, horsepower, and drivability are affected by deactivating key components of a computer-controlled system; a secondary objective is to establish a method to identify accurate and efficient vehicles with disabled components (Jones et al.).
In areas where low-pollution energy sources are used for electricity generation, all-electric vehicles and PHEVs tend to have lower emissions than similar conventional vehicles that run on gasoline or diesel. NOx emissions standards for light vehicles in 2025 represent a 98% improvement over 1975 and a major driver of U-shaped improvements. The results of individual vehicle emissions tests are often compiled to assess the emission performance of various classes of vehicles, the effectiveness of the test program, and several other emission-related regulations (such as changes in fuel formulations). Emissions related to the production of fuel used to power vehicles are known as “upward emissions”.
If you watch closely while powering your vehicle, especially on hot days, you can see these emissions as they go. By understanding the different types of vehicle emissions and their effects on public health and the environment, people can play an active role in reducing air pollution.