To Some Old Timers
Increase in rats and other vermin started when NYC apartment and other buildings were forbidden to burn rubbish daily.
To compensate for the removal of burning rubbish, NYC increased sanitation collections to three times per week in much of the city (every other day), but that still means trash is stored in or around the building for at least a day, sometimes two (weekends). If there is some sort of weather event such as a snow storm that calls the sanitation department's resources elsewhere, it could be days or weeks before normal collection resumes. All that time that rubbish is sitting, rotting and attracting rodents.
The other thing is the move away from metal rubbish bins to simply throwing bin liners full of trash onto the street. Many buildings do not even keep rubbish stored in metal bins on property, just stacked in bags. This has much to do with building design and or workers. Many apartment buildings do not have direct access to basements from the street. So rubbish and anything else in the basements has to be hauled up through the main lobby.
IIRC many City residents didn't like the old metal cans because of the noise created early morning or late at night as the things were banged about during collection. Then there is that NYC moved to compacting rubbish trucks with two men crews. While enough persons still place cans/containers of rubbish out that require dragging by one or two men to be emptied into the truck, a vast majority is in bin liners which is simply "flung" like footballs.
To deal with large amounts of rubbish between rubbish days many larger NYC buildings have installed compactors. However if they aren't kept clean and well sealed vermin are attracted there as well. And of course placing compacted rubbish into bin liners does not totally solve the problem of rodents getting at them.
Growing up we too could always tell when an incinerator in the area was fired up; can still remember the smell. Yes, remember the whiff of burning leaves as well. Every now and then someone doing *that* would either be careless and or the wind would change and a fire from minor to major scale would break out. Especially if the weather had been dry and there was *tinder* nearby that could be ignited by flying embers.
Speaking of old things in NYC apartment buildings, many still have their old coal fired furnaces/boilers. You know the ones with those huge metal doors that looked like something that belonged on a steam locomotive or ship.
Over the years all have been converted to burn oil. Originally it was the ghastly "bunker fuel" grade which was the lowest and most dirtiest (but cheap) oil for heating, but some buildings did upgrade to better quality of heating oil. About a year or so ago NYC began a program to finally ban the burning of cheaper grades of heating oil in order to deal with soot/particulate matter. This was seen as an air and health quality issue. In our own area of the UES for instance large numbers of buildings still burned that nasty cheap "bunker fuel".