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From: jerem@tekgvs.UUCP (Jere Marrs)
Newsgroups: net.auto,net.consumers
Subject: Re: Re: No Leaded Gas -- Now What? [trees]
Message-ID: <1078@tekgvs.UUCP>
Date: Fri, 29-Mar-85 02:36:16 EST
Article-I.D.: tekgvs.1078
Posted: Fri Mar 29 02:36:16 1985
Date-Received: Sun, 31-Mar-85 03:04:56 EST
References: <341@ho95b.UUCP> <256@rtech.ARPA>
Reply-To: jerem@tekgvs.UUCP (Jere Marrs)
Organization: Tektronix, Beaverton OR
Lines: 26
Keywords: alpha-pinene, peroxyactylnitrates, shibboleth
Xref: watmath net.auto:6277 net.consumers:2071
Summary: 


The natural haze in The Smoky Mountains and in the woods of the Northwest too 
is due to a natural photochemical smog caused by the reaction of alpha-pinene
(a terpene emitted by evergreen trees) with residual ozone formed by the sun's
ultraviolet irradiance (below 1900 angstroms). The ozone combines with the
pinene to form an oxidation product (a solid) which forms a light-scattering
sol (dispersion of a solid in a gas) which gives rise to the familiar haze.

The indians referred to this in the writings of Lewis & Clark long before
the blessing of internal combustion engines.

The distnctive smog formed in the atmosphere around cities is very different
although it is still a photochemical smog. The unburned hydrocarbons in the
air combine with ozone and the oxides of nitrogen to form peroxyacetyl-
nitrates which are kinda red colored giving the smog around cities a brown
caste so  familair.

Peroxyacetylnitrates are lachrymators which is why your eyes water in heavily-
polluted cities (e.g. Los Angeles).

I hope I didn't step into a hornet's nest.

						Jere M. Marrs
						Tektronix, Inc.
						Beaverton, Oregon
						tektronix!tekgvs!jerem