Jet exhaust analysis

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Offline johndiver

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Jet exhaust analysis
« on: 30/05/2005 06:56:39 »
A class-mate told me she was convinced the engines of commercial jetliners emit toxic chemicals that cause people living in cities to get sick ... etc.
Although I responded with the view that the majority of jet exhaust is water vapour and carbon dioxide she was adamant.
Does anybody know of a simple test (perhaps analysis of the light reflected from the jet trails?) to prove the myth/theory right or wrong?


Offline chris

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Re: Jet exhaust analysis
« Reply #1 on: 01/06/2005 09:04:09 »
Jet exhaust contributes heat, water, CO2 and particulate matter (as does any engine) to the atmosphere.

I'm not aware that it is more harmful that any of the other chemicals that we pump out closer to the ground, but air travel is certainly devastatingly bad for the planet, contributing more CO2 per person-mile than any other means of transport. (says the guy who has travelled all the way around the planet almost twice this year by air...ho hum).

As an aside, however, they say that every cloud has a silver lining and this is certainly true of air travel because it is thought to be provoking the formation of "noctilucent" clouds.

These are beautiful wispy clouds visible late at night in the north. They are very high (>50 km up) and are believed to be mainly the result of water condensing on the vapour and particulate exhaust trails of jets. They are a new phenomenon and were never observed prior to industrialisation at the turn of the century. They have, however, become much more common recently.


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Offline anthony

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Re: Jet exhaust analysis
« Reply #2 on: 03/06/2005 07:42:31 »
Burning fuel is rarely as clean a process as your year 10 chemistry teacher lead you to believe. There are well over 600 different chemicals present in a gas flame, not all are long lived. Most combustion, except under very controlled conditions will produce lots of products, whether that's in planes, trains or automobiles. Or for that matter on your toast in the morning. Many of these will be regarded as toxic, but toxic is a misleading term. You're eating toxic chemicals every days as part of a balanced diet. Caffine for example, is listed as a toxic chemical, indeed, it is probably more toxic than many of the chemicals in jet exhaust.

As to the original proposition, that jet exhausts are making people in cities sick. Could it not just be their coffee and toast in the morning? It's difficult to prove, but no doubt people are being exposed to a broader mix of toxic chemicals than ever before, lots of them voluntarily. But our ancestors burnt cow manure in small huts and we're living much longer than they ever did, so I wouldn't worry about it. The contribution of jet exhausts to global warming, or global dimming, is a much more important question.