Neighbour is burning something weird

[AInightingale]

I live in an area where about half of homes have gas, and the other half use home heating oil. For the past couple of weeks, I've noticed a very strong smell of something I feel isn't heating oil. I think it may be diesel, possibly the agricultural/black market stuff because he's that kind of man, all kinds of stuff going on, selling contraband fags etc. While I wouldn't be so petty as to report someone for that, I am concerned about our health here, stuck beside him. So what are we breathing in and can diesel be burned in the open air like this? The air is quite heavy and foggy here atm so the fumes are hanging around

Heating systems only work on one kind of oil or another. You can't change fuel, the system would break down.

Does he have a generator instead maybe?

Well, I did read that you can use diesel in an emergency like when it's very cold and your oil has run out, but it's only supposed to be for a couple of days at most. Diesel and kerosene are supposed to be very similar.