Why don't computers have air filters?

I've been cleaning out numerous Dell computers that collect lots of dust in a short time. Seems the air flow is rather efficent from the floor to cpu they out the back... the dust inside the box gets unreal...

Why don't computers have air filters?norton 360

okay...

you could have front intake fans (had one before) ...pulls air in from the front. The you could have a few rear fans that blow air out...its a type of airflow regulation that allows circulation of airflow.

you would also have your CPU/heatsink fan.

Also, there is an ANTEC Sonata that has an air filter so-to-speak. It's great. It catches all the dirt and crap flying around. When I empty it every month, my case is clean...and there is plenty in that filter.

Why don't computers have air filters?photoshop

But some computers do. If you build your own computers, you can buy some that have air screens, I wouldn't call them air filters but rather air screens that do help keep out the dust, you can even remove them and clean them from time to time. And computers do suck in air and blow air out, again, depending on the case you have, mine takes air in from two fans in the back, two fans in the side and blows it out from the top and from one in the front. That's not including the CPU fan and my GPUs have passive coolers on them (since I have good air flow and plenty of fans). I also live in a low dust environment and my PC is well protected from dust.
They're rare, I think, but not unheard of. I've seen cheap little ''snap-on'' filters that fit over the case fans and vents that sort of filter the air on the way in, but by looking at them, they don't look like they'd do a lot of good, really. I'm sure with some poking about you could even find some quality stuff, but I just googled very quickly and didn't find anything.