What is a contrail made of? Mostly ice, since the primary exhaust emission of a jet aircraft is water vapour, which freezes within a couple of seconds, and forms the visible part of the contrail. If the air is fairly humid, then the contrail can persist for quite a while, and even spread out, turning into a sheet of cloud.

Jet engines also emit the usual things engines emit: carbon dioxide, smoke, and small amounts of unburnt hydrocarbons, oxides of nitrogen, carbon monoxide and small amounts of other things. Aircraft emissions are regulated.

Some people think that if a contrail stays in the sky for a long time, that this is very unusual, and that it means the government is spraying something in the air, either to change the weather, or to poison people. They call these persistent contrails “chemtrails”

Of course, persistent contrails are nothing new, they have been around at least since the 1940’s - when planes were able to get to sufficient altitude. But some people believe in the “chemtrail” theory so strongly that they ignore this fact, or they say “well, SOME of the persistent contrails must be chemtrails”.


One person who was convinced of this was Clifford Carnicom, who put a report on his web site that he said showed that “contrails” were poisoning the air. What happened was someone called Sue Miller collected three samples of rain and snow. She then sent them to someone called Therese Aigner, who then sent them to a lab to be analyzed for Aluminum, Barium, Calcium, Magnesium, and Titanium.

When the results came back, they detected very low levels of those elements, but Miller said: “This devastating data points to a deliberate atmospheric release of massive quantities of material containing Aluminum, Barium, Calcium, Magnesium, Calcium, and Titanium.“

Scary stuff. But what do these results actually mean. All three samples were about the same, so lets look at the first one:

  Result MDL EPA
Aluminum <0.100 0.100 0.200
Barium 0.100 0.020 2.000
Calcium <1 1 N/A
Magnesium <1 1 N/A
PH Field 7.2   6.5 to 8.5
Titanium <0.050 0.100 N/A

The “Result” column is the amount the substance found in mg/L (milligrams per liter). The units here are important. Sometimes concentration is measured in ppm (parts per million), which is the same as mg/L. Sometimes they are measured in ppb (parts per billion, so 1 mg/L = 1 ppm = 1000 ppb). Make sure you use the right units when looking at things like this

The second column, the MDL is the “Method Detection Limit”, defined as the smallest amount where you can be 99% sure that there is a non-zero amount of the substance. If a number is below the MDL, then you can’t be sure that it’s just instrument noise. If something is less than MDL, then you can’t say with any certainly if any of the substance exists. The best you can say is “there might be some, but we can’t say for sure, but it’s definitely less than the MDL”

The third column (EPA) is one I added for some perspective. It lists the allowable limits for drinking water from the EPA. If the EPA has not set a limit, then I put N/A.

Most of the substances are lower than the MDL, so we can’t really say if there is actually any of these substances in the sample. But the “chemtrail” people say “Tests were ordered for several elements that should NOT be present in normal rain/snow“. So is that right? Should the results come back as zero?

There are two problem here. Firstly if there actually WAS zero aluminum in the samples, then the tests would STILL come back as “less than MDL”, because of “noise” in the instrument. If an instrument has an MDL level, than means it can’t detect zero values with any confidence.

Secondly, we DO expect these substances in rainwater. Aluminum is the most abundant metal in the earth’s crust, so is found in dust in the air, and hence in rainwater. The EPA says:

  • Virtually all food, water, air, and soil contain some aluminum
  • Everyone is exposed to low levels of aluminum from food, air, water, and soil.

The EPA has not set safety limits for aluminum, the limit listed above is for taste and color reasons.

Calcium, likewise, is found in abundance in rocks (and hence airborne dust), as is magnesium and Titanium. There are no EPA limits set, because they are not particularly toxic.

The only substance with a measurable result was Barium. This was present in the samples a concentration that was just 5% of the allowable EPA limits for drinking water. Not a dangerous amount, but should it be found in the air (hence rainfall) at all? The CDC says ”

  • Barium gets into the air during the mining, refining, and production of barium compounds, and from the burning of coal and oil.
  • The length of time that barium will last in air, land, water, or sediments depends on the form of barium released.

So yes, barium is in the air, from such things as burning of coal and oil. And seemingly from this test result, not at a dangerous level.

Free Image Hosting at www.ImageShack.usQuickly looking at the pH value - that measures the acidity or alkalinity of a solution, where a value of 7 is considered neutral. Drinking water ranges from 6.5 to 8.5, so the value here of 7.5 is nothing unusual for drinking water. “Acid rain” for example is defined as having a pH of less than 5.0. But rain is usually slightly acidic (pH of around 5.6) because of the carbon dioxide in the air, however it varies depending on location and atmospheric pollution (and can be has high as 8.5) . In the US rainwater is usually under 5.6, so getting a value of 7.5 is somewhat suspicious. since rainwater pH is constantly being measured, it’s very unlikely that such a high pH would have gone unnoticed. The fact that this one set of sample has a high pH suggests that either the samples were contaminated during collection, or that they were actually ground water, and not rainwater.