Diesel Exhaust:
1995 California Numbers
On road diesel engines produced 15,680 tons of particulate matter
Off road diesel engines produced 9,820 tons of particulate matter
Stationary diesel engines produced 1,400 tons of particulate matter
Your tractor would obviously be included in category two, off road diesel engines. Why is particulate matter from diesel engines particularly dangerous. They contain Polycyclic Aromatic Hydrocarbons a proven dangerous substance and nano particles which invade lung tissue much deeper due to their tiny size. Infants and children are more seriously affected by this due to the relative smaller lung tissue volume. Studies have proven that PAH causes lung cancer. All credible health organizations agree on the risk and damage of these pollutants.
I posted the 1995 numbers to show the volume of particulate matter early in diesel emission control systems. No doubt these numbers have fallen dramatically and will continue to fall with more vehicles covered and better systems evolving.
You have no right to create dangerous pollutants that affect the lives of others. Doing that is simply a form of trespass, serious trespass. You have a duty to do your part to prevent this problem, even if it costs you money to do so. It's called the total cost of operating. Sure it would be less expensive for one to dump used motor oil into the ditch and drain ethylene glycol on the ground. That simply shifts the cost from the person using the oil and coolant to everybody else and that is not a fair deal.