Not all environments are as dusty as the next.
There are a myriad of factors that play into this, both environmental plus human caused.
Depending on the region in which you live, you easily could have lots of dust around your residence, or even airborne sand if you happen to be in the desert. Mold spores in the air plus on the ground outdoors vary to essentially the same degree. Before even looking at human factors, you already have a lot of variation in what affects a single space versus another. What makes all of this worse is when you unite these natural environmental irritants with construction work. You could have ceramic dust in the air if there is concrete that is being cut nearby. Likewise, if trees are being cut or wood residences being built, you could have a sizable amount of saw dust with whatever natural dust is flowing around. You can make this a great deal worse within the confines of your residence by simply doing laundry more than the next person. Since my region is packed with irritants, I use a good air purifier to clean out most of my indoor air before it gets into my Heating, Ventilation plus A/C machine plus moves into the HVAC duct throughout the house. I will often find lots of particulate building up on the air purifier filters as abruptly as two weeks after replacing them. It’s easily worth the hassle plus the price, because my asthma concerns have dropped a great deal. I can’t even imagine living without a solid air purifier now that I’m so used to them. As long as I can afford to buy plus replace the air filters, I will use the machines until the day I die.