Have you ever been in this situation? You just got invited over to a relatives house and then you and a buddy get asked to move a used appliance to a nearby house.
When you get to the house where the used appliance is going, you open the door and a pungent odor hits you! You try to breath normally, but your reluctant to breath at all. You thought it looked safe and you were happy about the whole thing, but now your holding your breath or thinking of putting your shirt up around your head to deal with the odor.
Sometimes its just the basement that has the odor from stagnant water or mold that growing in the walls or floor. In any case, litter boxes, urine, mold, or mildew growing in a house greatly affect the people that live there! It can actually be toxic, but humans learn to tolerate it. Why?
In most homes the quality of indoor air is effected by many factors including nearby farms, factories, pollen, dander, smoke from cigarettes, smoke from fire and a combination of years of neglect! Dog and cat urine just add to the odor to give a real shock to average visitor.
Get a download of my book "Making Your a House a Home" and get the word out how to overcome these and a 100 other issues that effect your home.