This smoke at the bottom of the street is not from a fire. Rather some poor family's house is getting fumigated. Fumigation is mandatory in Cuba. Every house, apartment, office and place of work gets regularly fumigated. Official show up with ghost-busters-like machines and the the dwellings and fill it with white smoke until it's escaping through every crack.
We've had the displeasure of being guests and spending a the night in a couple of home that have recently been fumigated. The smell is unpleasant and, I suspect, not good for you. But hey, anything to fight the enemy, dengue fever, in this case.