You can see the requirements in the Laboratory (Microscope button in the lower part of the screen). You will need Tech Points (Microscope counter) to do the necessary research, which will allow you to unlock the Helicopter, the Sprinklers, or the Environmental Condenser to improve your performance in the city.

To get these Technology points, you need to get more Prestige (star icon) by extinguishing fires. We will recommend you to read the FAQ related to Prestige in this same FAQ section. 

 

If you still cannot see the Prestige or the Technology Points icon, don’t worry! They will appear eventually when you are a bit more advanced in the game.