Emissietests

Emissietests are procedures to measure and evaluate the amount of pollutants released by a device, process, or activity. They are used to assess compliance with environmental standards and to estimate a source’s contribution to ambient air pollution. The term is most commonly applied to motor vehicle exhaust, but also covers industrial processes, power generation, and consumer products that emit volatile organic compounds or other pollutants.

In transportation, emissietests typically assess exhaust emissions such as carbon monoxide, carbon dioxide, nitrogen oxides, hydrocarbons, and particulate matter, as well as evaporative emissions from fuel systems. Tests may be performed in laboratories on engines mounted in test cells, on chassis dynamometers, or in real-world conditions using portable measurement equipment.

Common methods include standardized laboratory cycles (for example, transient or steady driving cycles), laboratory exhaust analyzers, and portable emission measurement systems (PEMS). Metrics include emission factors per distance, per energy consumed, or per kilogram of fuel used, together with preventive maintenance indicators.

Regulatory frameworks establish permissible emission limits and certification procedures. International and regional standards include European Union Euro standards, United States EPA and California air resources board standards, and UNECE regulations. Real driving emissions programs seek to quantify emissions under typical operating conditions.

A typical emission test procedure involves conditioning the device, instrument calibration, sampling from the exhaust stream or a test chamber, analysis by appropriate detectors, and calculation of results. Quality control and traceability are maintained through reference materials, calibration gases, and per-test reporting.

Data from emissietests informs type approval, environmental policy, and consumer information. Ongoing developments focus on reducing the gap between laboratory results and real-world performance, improving measurement in low-emission vehicles, and expanding testing to non-road and stationary sources.