2016 footage of an ex-CIA director talking about using stratospheric aerosol injections to reverse global warming has been misinterpreted.
The video in question has been taken out of context. On June 29, 2016, PBS interviewed Brennan about various global affairs, including the U.K.'s decision to leave the EU, the Istanbul attacks, and ISIS. Brennan also discussed the various uses of biotechnology. He used an example of geoengineering, saying: "It could potentially help reverse the warming effects of global climate change. One that has gained my personal attention is the stratospheric aerosol injection, or SAI, a method of seeding the stratosphere with particles that can help reflect the sun's heat in much the same way that volcanic eruptions do."
According to the École Polytechnique Fédérale de Lausanne (EPFL), a research institute in Switzerland, SAI is a method in which reflective aerosols are sprayed into the stratosphere by an aircraft, tethered balloons, high-altitude blimps, or artillery. These aerosol particles reflect sunlight into space. It adds that SAI would not reduce the concentrations of greenhouse gases in the atmosphere but instead would cool the planet and alleviate some negative consequences of global rising temperatures.
There is much debate about whether stratospheric aerosol injections would be a good idea. As climate Matt Simon wrote for Wired, "the science isn’t ready. This anthropogenic geoengineering might trigger unintended effects, like droughts in certain regions and massive storms in others."
Importantly, stratospheric aerosol injections aren't even happening yet, and there is no evidence the practice is causing allergies or trouble breathing. Mayo Clinic has listed pollen, animal dander, dust mites, and mold as common causes of allergies.
Logically has previously debunked several claims regarding this conspiracy theory, such as the one that alleges condensation trails left by aircraft in the sky contain toxic chemicals that are harmful to humans.