Whether you are outside walking the street or just hanging around inside your house, you will definitely encounter dirt. It is stubborn and gets into a lot of places. You really cannot leave a glass of your drink out in the open due to the fear that those particles will get into it. Complex machines such as an air conditioner may have some sort of dirt-air separator inside them, but scaling that up to handle environments as large as your regular rooms could just be a pipe dream.
Some people just choose to accept it as part of life. They would not mind getting a few specks in their eyes or in their food, as it does not cause tremendous harm anyway. Filters are effective in blocking out dirt and other small particles, but you can also find them or a different iteration in some everyday gadgets.
The universal drink for those who are busy and need to stay awake, coffee is best consumed while it is hot. And you can argue that brewed ones taste the best. Whether you are at a fancy cafe that has expensive equipment or at home using your own inexpensive machine, coffee makers feature filters prominently. This ensures that you do not get a drink that is highly diluted and therefore lack the strong flavor that you are eager to drink.
If you think about it, the grounds themselves serve as a filter for the hot water that drips from above. Every drop has to go through the grounds. This will then accumulate while the filter lets the coffee drip out of its porous surface. Once it reaches your mug, you should enjoy a sip that is free from any grainy particles. This should give you a smooth coffee-drinking experience.
The computer case houses all of its components, from the motherboard to the video card. The more capable ones used for gaming and rendering draw a lot of power from the wall outlet. This naturally translates to the heat generated inside the case. So to cool it down, you need intake and exhaust fans. The problem with that is that it could attract dust, which could damage or shorten the life span of your parts, so you need dust filters. There are different kinds that you can use, but most cases have these already built-in. Try not to open your PC chassis for several months. You should expect that to accumulate thick layers of dust everywhere. You will have to disassemble that if you want to thoroughly clean it.
Having any kind of pollution or irritant spread through the air is difficult because you cannot easily escape them. Humans are designed to breathe in oxygen as a natural and involuntary function. This also makes it easier to inhale contaminated air. If you want to protect yourself from this, you need a physical barrier that blocks out the unwanted particles, but not so much that it hinders you from breathing.
There are different masks that you can use, depending on the severity of the situation. If you are concerned about viral droplets or residual smoke, you can use light surgical masks. These do not compromise your vision or head mobility. For more extreme cases such as a large fire, you will notice that firefighters wear larger masks that protect the whole face and are attached to an oxygen source. The thick smoke is very difficult to filter out, so you need something more substantial.
Filters come in many shapes, but all aim to pursue a degree of segregation that is not easily visible to the naked eye. Only then will you realize that there is much more going on around us. Air and water carry invisible particles, but you have ways to manipulate them. If your hands can’t catch them, let the filters do their jobs.