In time it will become black with all the stuff it is capturing and will need to be cleaned or replaced. Without a laboratory test you cant tell how much is getting through the filter. No filter stops all the particles since the filter also has to let the air through and so microscopic particles will still get through with the air.
In time it will become black with all the stuff it is capturing and will need to be cleaned or replaced. Without a laboratory test you cant tell how much is getting through the filter. No filter stops all the particles since the filter also has to let the air through and so microscopic particles will still get through with the air.