Nitrous oxide (N2O)

Name PRTR	Nitrous oxide (N2O)
CAS no	10024-97-2
Molecular formula	N2O

Nitrous oxide is a colourless gas with a slightly sweet taste and odour. Nitrous oxide is a greenhouse gas. In order to compare the effect of different greenhouse gases, emissions are converted into carbon dioxide equivalents¹.

Uses

Nitrous oxide (laughing gas) is used as an anaesthetic and for pain relief within healthcare, for example during childbirth and in dentristry². In addition, nitrous oxide inhibits microbial growth and is used in food packaging. The gas is allowed for all types of food³. Other applications include propellants, for example in cartridges for whipped cream dispensers, and to improve the combustion efficiency in engines (so called nitrous oxide system, NOS)⁴.

Sources and transportation pathways

Nitrous gas is produced synthetically, but the gas is also emitted to the environment from natural sources such as swamps and forest soils. Farmland that is fertilized with nitrogenous fertilizers also emits nitrous oxide⁵.

Operations such as chemical industry, production and processing of paper and wood, the energy sector and waste management are the most important anthropogenic sources in Sweden.  Wastewater treatment plants also contribute significantly to emissions. The most important transportation pathway is by air.

Effects on environment and health

Emissions of nitrous oxide affect both the environment and humans. Nitrous oxide is a greenhouse gas that contributes to the increased greenhouse gas effect⁶. The increased greenhouse gas effect results in an increase of the average temperature on earth, which for example leads to climate change and rising of the sea level^7,8. Nitrous oxide also contributes to depletion of the stratospheric ozone⁹. A thinner ozone layer leads to increased radiation on earth.

Breathing nitrous oxide may cause hypoxia¹⁰. Using nitrous oxide can also worsen the symptoms caused by vitamin B12 deficiency and folic acid deficiency. The most important route of exposure is through breathing.

International agreements and regulations

Nitrous oxide is regulated by the UN Framework Convention on Climate Change (UNFCCC), the EU MMR regulation (525/2013/EU) and the EU ETS (2003/87/EU). The UN Protocol on PRTRs and the EU E-PRTR regulation regulates how data on nitrous oxide emissions is made available.



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¹ http://www.naturvardsverket.se/Sa-mar-miljon/Statistik-A-O/Vaxthusgaser-konsumtionsbaserade-utslapp-fran-exporterande-foretag/Koldioxidekvivalenter/
²http://www.fass.se/LIF/
³ https://www.livsmedelsverket.se/livsmedel-och-innehall/tillsatser-e-nummer/sok-e-nummer/e-942---dikvaveoxid?_t_id=1B2M2Y8AsgTpgAmY7PhCfg%3d%3d&_t_q=dikv%c3%a4veoxid&_t_tags=language%3asv%2csiteid%3a67f9c486-281d-4765-ba72-ba3914739e3b&_t_ip=195.67.7.30&_t_hit.id=Livs_Common_Model_PageTypes_ENumberItemPage/_c1869785-0619-4595-91d5-461b3f31f7a9_sv&_t_hit.pos=1
⁴ https://sv.wikipedia.org/wiki/Lustgassystem
⁵ http://www.naturvardsverket.se/Sa-mar-miljon/Klimat-och-luft/Klimat/Darfor-blir-det-varmare/Andra-vaxthusgaser/
⁶ http://www.naturvardsverket.se/Sa-mar-miljon/Klimat-och-luft/Klimat/Darfor-blir-det-varmare/Andra-vaxthusgaser/
⁷ http://www.ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_SPM.pdf
⁸ http://www.smhi.se/kunskapsbanken/klimat/vaxthuseffekten-1.3844
⁹ A. R. Ravishankara, John S. Daniel, Robert W. Portmann (2009). Nitrous Oxide (N2O): The Dominant Ozone-Depleting Substance Emitted in the 21st Century. Science, Vol. 326, Issue 5949, pp. 123-125.
¹⁰ https://rib.msb.se/portal/template/pages/kemi/Substance.aspx?id=520&q=lustgas&p=1