question – about tenants’ requests, what exactly am i responsible for?

Hi,
I have recently rented my apartment, which is a prewar walk-up in NY, with no manager or doorman.

My tenants did a roast last weekend and the fire alarm went off. They called the fire department which detected the levels of carbon monoxide slightly high; then they called me saying that there was a problem with the stove.
I have called a technician who sent me a report saying the stove was perfectly fine and that the incident was caused by the lack of exterior exhaust and therefore the accumulation of smoke when they opened the stove. The apartment has an open kitchen and, like most buildings of the same period, and visibly so, no exterior air exhaust in the kitchen.
 
Now, I have a bill of $70 for the technician saying "no problem" and the fire dept coming. Who pays?

This seems to be a recurrent problem… 
One month ago it was a problem with a circuit in a lamp of the kitchen: smoke was coming out of it. Frightening, isn’t it? I sent someone and it ended up being the bulb badly screwed – again another bill;

I received an email because of a "light" on the dishwasher – that one was easy to detect fortunately: it needed more product…
 
what are exactly my responsibilities in these cases? Do I have to pay all bills?