Acoustic and Emission technologies

NOx, PM, HC, CO, SOx, CH4, Diesel, Gass and Petrol

Tuesday, 24 July 2012 08:30 A3D

Emissions out of combustion engines

During the combustion proces, exhaust polution occurs. Engine exhaust gas contains pollutants which are harmful to man and the environment, known as carbon monoxide (CO)hydrocarbons (HC)nitrogen oxide (NOx), Oxides of Sulfur (SOx) and particulate matter (PM).

Exhaust and harmful emissions

Exhaust emissions are the non-useable gaseous waste products produced during the combustion process. “Exhaust gas” is the standard term used to describe the waste gas from internal combustion engines.

In addition to harmless products such as water vapour, carbon dioxide and nitrogen, engine exhaust also contains pollutants which are harmful to man and the environment: carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxide (NOx).

Harmful emissions only represent a very small share of the overall emissions of a modern engine. Only 1.1 % for the petrol engine and 0.2 % for the diesel engine. The majority of exhaust consists of nitrogen, water and carbon dioxide.

However, it is important that the comparatively small quantity of harmful emissions is also rendered harmless.



Carbon monoxide (CO)


Carbon monoxide is a colourless, odourless and tasteless gas. The compound, consisting of carbon and oxygen, is formed during incomplete combustion of carbon-containing substances and is very poisonous to the respiratory system.

As soon as it is inhaled and enters the bloodstream it prevents the bonding of oxygen to the red corpuscles. A concentration of 1.28 percent carbon monoxide in the air will cause death from suffocation within 1 to 2 minutes.

Read more about CO (Carbon Monoxide)...

Hydrocarbon (HC)

Hydrocarbons are chemical compounds which consist only of carbon (C) and hydrogen (H). They can be found in large quantities in crude oil, natural gas and coal, where they are the actual “fuel”. Some hydrocarbon compounds cause cancer.

When exposed to sunlight, hydrocarbons and nitrogen oxide react to form ozone. In the lower layers of the atmosphere this is a hazardous substance.

Read more about HC (Hydrocarbon)...

Nitrogen oxide (NOx)

Nitrogen oxides are the gaseous oxides of nitrogen (N). They are abbreviated NOx because of the various possible compounds with different numbers of atoms: N2O, NO, N2O3, NO2, etc.

Read more about NOx (Nitrogen Oxide)...

Oxides of Sulfur (SOx)


Oxides of Sulfur can aggravate respiratory illness and heart and lung disease. It forms particulate matter (PM) and is a primary cause of acid rain. Most vehicle emissions studies do not consider SOx because vehicles contribute such a small portion of the total amount emitted by human activity. In 2006, ultra-low sulfur diesel (ULSD) regulations reduced the contribution of SOx even further. Although SOx is not a major concern for conventional and alternative fuel vehicles, it is a concern for electric vehicles since electricity generation is the largest source of SOx.

Methane (CH4)

Methane  is a chemical compound with the chemical formula CH4. It is the simplest alkane, the main component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel.


Read more about CH4 (Methane)...


Particulate Matter (PM)

Particulate Matter can aggravate asthma, emphysema, bronchitis, heart disease, and lung disease. It is a carrier of many toxic compounds, contributes to haze, pollutes fresh and coastal waters, and contaminates farmland and natural ecosystems. PM is emitted directly from vehicles (especially diesel) and is formed through the atmospheric reactions of NOx and oxides of sulfur (SOx).


Read more about PM (Particulate Matter)...

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Pollutions (contaminants) Index

- NOx (Nitrogen Oxide)
- PM (Particulate Matter)
- HC (Hydrocarbons)
- CO (Carbon Monoxide)
- SOx (Sulfur Oxide)
- Fuel and Engine types

Diesel - Diesel engine


Gas - Gas engine


Petrol - Petrol engine


Solutions, Products, Service and Support


Solutions - Products


Service and Support Standards (norms), downloads, installation, maintenance, tools and more...


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Last Updated on Wednesday, 22 May 2013 11:06