I would like to express my viewpoint as far as the trains being near the Columbia River or running through Spokane.
I grew up on a street three blocks from a rail line. It carried coal trains on a regular basis. I do not remember how often as I am now 72 years of age. I do remember that we heated our home with coal; coal gleaned from the rail cars that dropped coal as they passed. We got enough coal to never have to buy anything else to heat with. I am sure there must have been others in our neighborhood who did the same thing. The area we used was about three city blocks to gather enough coal to heat our house all winter.
You can see from this one example how much coal they dropped. That doesn’t include the dust that flew every time a car hit a track joint.
Perhaps this will shed a little light on how much they pollute as they pass by. If you are going to allow it, at least require covers on the cars instead of allowing them to be open.