Tailpipe emissions refer to the pollutants that are released into the atmosphere through the exhaust pipes or tailpipes of vehicles, such as cars and trucks. These emissions include gases like carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbons (HC) and particulate matter (PM). The composition of these emissions varies depending on the type of fuel used by the vehicle, its age, maintenance, and operating conditions. Tailpipe emissions are a significant contributor to air pollution and have negative impacts on public health, climate change, and visibility. Governments around the world regulate tailpipe emissions through emission standards that set limits for specific pollutants in order to reduce their levels and improve air quality.