We got large amounts of that dust as well. an most of our solid tires are sort of beige/orange (muted colour vision) but all Electric. we only have 3 Dieseles, non of which runs much indoor, at most some short trips inside to pick up or drop of certain goods. so as mentioned (Old tread, but anywho) by L1ftmech, in good detail, it's a large combination of factors. LPG, ran only a short amount of time would have little to no impact on the dust levels.

we got 8 4-ways in the 2.5t class(sichel and BT) and 2 3t combilifts doing the main inddor runnings for up to 13 hours a day. and I'd say anything within head height gets a dust covering in 2 months time if it's not moving. Even timber packets placed on top at 6meters height will get quite the dustcovering if it's allowed to lie there for a few months (solid wood flooring in particular, as the movement of that product is rather in leaps and bounds)

Even kicking out the customers when we went full distribution unit a year back hasn't really helped. I thought getting rid of all those cars and trailers running through our storage would help, but to me it still pretty dang dusty, seems less on the floor though.... I suspect cars brought in heavier dust particles, particularly when it was wet.