Pollen filter is just like air filter,air filter is for your engine, but pollen filter is for your interior it prevents dust and other particles entering your interior through Air Conditioner/Heater.
I hope there should be some sort of filter in each & every car to prevent dust and other particles entering your interior through Air Conditioner/Heater!
I hope it is mandatory thing & it should be present!
Pollen Filter. As the name itself suggests, This filter helps to prevent the pollens and other particles from entering inside your vehicle through Air Conditioner Vents. Its present in some of the cars, Check the attached PDF explaining to find its location pictorially.
In each vehicle pollen filter is placed in different places.
For Punto i think the pollen filter is placed under the the dashboard in left side.
Pollen filter is truly called cabin filter.