The Environmental Protection Agency, along with all other academic, scientific and government mandated or institutional stakeholders have long since declared that internal air, that which you would normally inhale and exhale indoors but never actually see (you could feel it, however), is a lot higher in pollution levels than the outdoor air. You may well find this astounding given that there are just so many high and heavy smokestacks billowing long and heavy columns of smoke and gas out there.
You would have thought that indoor air is a lot less exposed to heavy industry areas or nodes. But you would be surprised to learn just how quickly and easily outdoor pollutants can creep into the indoor air environment. You never actually see this happen. But you may feel it. Or will you, given that so many domestic and commercial consumers have wholeheartedly or aggressively embraced the installation of air conditioning and/or HVAC systems.
There is a counter-effect here in the sense that you are never able to tell for certain whether your internal air is one hundred percent devoid of harmful or toxic pollution. You need the services of an air management design phoenix az company to help work your way around this conundrum. You are able to feel the air around you but it is a false fallacy. When it is cool inside it is only because your air conditioning system has allowed it to be so.
And when it is warm inside while it is blowing gales or storming outside, it is all thanks to your installed central heating system. As comfortable as it may feel, you still never can see it. And you are also left wondering why under such comfortable circumstances, people are still getting sick.