What are they spraying via chemtrails that cause a white residue on everything and widespread sinus problems?

I know the difference between a contrail and a chemtrail, which makes this occurence rather alarming. After several of us observed jets making a bunch of chemtrails in a checkerboard pattern above us we noticed people have started having sinus problems in this area. About 80% of people who come into my work is/are complaining of sneezing, myself included, since the chemtrails were sprayed. The white residue is visible on plants, trees, cars, etc throughout a very widespread area.