Who are aware of these?

Pilots, farmers, gardeners... Lots of people.

Did you mean contrails?

http://rationalwiki.org/wiki/Chemtrails

Chemtrail history and culture


Chemtrail theories were first brought to prominence in the 1990s by paranormal pusher and talk radio host Art Bell. Aided by the internet, it is now a world wide phenomenon and chemtrail watchers all over the globe exchange photographs and videos of their favorite contrails on forums and youtube.

Chemtrails were mentioned in US House Bill HR2977,[5] October 2, 2001, which banned various types of weapons in space. The reference to chemtrails was eventually removed, but the original inclusion is cited as evidence that they are a real phenomenon. Given that the original bill was introduced by Dennis Kucinich, it perhaps reveals more about Kucinich than about whether chemtrails are real.

The chemtrail conspiracy is most popular among those familiar with the New World Order and those who claim that the spray is designed to pacify populations, either by making them sick, or some sort of mind control. Like many other pseudoscientific terms, earnest use of the word "chemtrails" immediately identifies the person using it as a crank, and is enough to harm credibility and provoke ridicule among those of a more rationalist disposition.

To a 'conspiracy nut', rationalist disposition just means you like having your bum and brain spanked by the government.

Theories like "chemtrails" just go to show that no matter what kind of bollocks somebody puts out, there's a million nutters out there who will believe it.