I live in an area that is very dry. Our humidity average runs about 15%. We live with static. This is what I do:
Put about 1 tsp of fabric softener in a medium to large spray bottle and fill with water. Mix well and spray lightly on the inside of trousers. They will be slightly damp, you can put in dryer for a minute or use hair dryer.
If you don't want to do that, you could try to rub a dry softener sheet on the inside of the pants and see if that will do. That works depending on how much humidity is in the air.