I live in an apartment building and the one across from me makes a looud machine sound sometimes. Last night it was louder than ever before and then it stopped for a bit. 20 minutes later it came on blasting what I would say dangerously loud, and I looked at the top of the apartment building from me and white smoke was billowing out the chimney. There was no smoke smell or 911 called so it wasnt a fire. I am just concerned cause I have no clue what this sound was and it sounded dangerous. It sounds like a broken ice removal truck that is about to explode.
That would likely be the boiler used to keep the building warm. That is where the white smoke is coming from. The colder it gets the more white smoke you will see because steam is more visible the colder it gets. If you are concerned about the noise then consider talking to someone looking after the building such as the clerk, cleaner, or owner of the building.