Medical experts advise the public on the importance of wearing sunglasses to protect the eyes from UV; for adequate protection, experts recommend sunglasses that reflect or filter out 99-100% of UVA and UVB light, with wavelengths up to 400 nm.
In 2008, a KSLA news investigation found that a substance that fell to earth from a high altitude chemtrail contained high levels of Barium (6.8 ppm) and Lead (8.2 ppm) as well as trace amounts of other chemicals including arsenic, chromium, cadmium, selenium and silver.
Chemtrails have nothing to do with the jet engine combustion process. They are often laid in a grid-like pattern by multiple planes (even drones) where they disperse slowly taking on the appearance of odd, at first narrow, but widening, smoky clouds until merging together to form, if sufficiently numerous, an aerosol bank that obscures the blue sky and gives the appearance of a dirty white overcast.