The air filter on an air conditioner [AC] exhibits the snowball effect - or maybe also the positive feedback loop [COMPACTIDEA]

Initially its filtration power / ability depends solely on the design of the material used to create the filter sheet. However, as dust and other filtered particles start to accumulate on the filter, the filtration power grows, because the extra particles that have now settled on the filter create further and tightened restrictions on the flow of even smaller particles. And this process continues.