尾气

廢氣是指車輛內的燃料（如天然气、汽油、柴油、重油、生物柴油混合物或煤）經過燃烧而排放出来的氣體。根据車輛引擎的类型，廢氣通过排气管等不同的方式排放到大气中。

机动车排放廢氣会导致空气污染，并且是一些大城市產生煙霧的主要因素。根據麻省理工学院2013年的一项研究表明，仅在美国，每年就有53,000人因汽车廢氣排放而过早死亡。根据同一所大学的另一项研究，在英国，仅廢氣造成的交通烟雾每年就会导致5,000人死亡。

然而近代研究顯示，汽車輪胎與路面摩擦所産生的有毒懸浮粒子比廢氣所産生的空氣污染更嚴重。

客车排放统计
火花点火引擎
火花点火引擎中：

引述
外部链接

• [http://www.arb.ca.gov/research/health/health.htm Health and Air Pollution] Publication of the California Air Resources Board
• [http://www.qfilter.com/Resource.aspx/DocumentDetail/15 The Encyclopedia Of Filters - Dust Collection] An overview of the science of dust collection systems, including those used for pollution control.

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*[https://web.archive.org/web/20150411064613/http://www.chevron.com/documents/pdf/MotorGasTechReview.pdf Chevron Motor Gasoline Technical Review]
*[https://web.archive.org/web/20150411064644/http://www.chevron.com/documents/pdf/DieselFuelTechReview.pdf Chevron Diesel Fuels Technical Review]

*柴油廢氣：
** [http://www.osha.gov/SLTC/dieselexhaust/ U.S. Department of Labor Occupational Safety & Health Administration: Safety and Health Topics: Diesel Exhaust]
** [http://www.osha.gov/SLTC/dieselexhaust/chemical.html Partial List of Chemicals Associated with Diesel Exhaust]
** [https://web.archive.org/web/20051031101139/http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s069dies.pdf Diesel Exhaust Particulates: Reasonably Anticipated to Be A Human Carcinogen]
** [http://ajrccm.atsjournals.org/cgi/content/full/159/3/702 Scientific Study of Harmful Effects of Diesel Exhaust: Acute Inflammatory Responses in the Airways and Peripheral Blood After Short-Term Exposure to Diesel Exhaust in Healthy Human Volunteers]
** [https://web.archive.org/web/20080414094408/http://www.losh.ucla.edu/catalog/factsheets/diesel_english.pdf Diesel exhaust: what you need to know]
** [http://www.dieselnet.com/resources.html DieselNet: Internet Resources]
** [http://www.dieselnet.com/tg.php#emi DieselNet: Diesel Emissions]