In order to keep outdoor pollutants outside, shoes should be taken off near where you enter the house. Outdoor shoes track in a vast majority of the dust and chemicals found in household rugs and on floors (this includes allergens, pesticides, and lead, plus other carcinogens and endocrine disruptors).

Taking off your shoes before entering a house is the public-health equivalent of washing your hands. A large majority of the dirt in any home arrives on the soles of our shoes, and removing them will help keep your house cleaner. Mud, water, snow, and animal feces are not pleasant, but the real issues here are the invisible ones: pesticide residues if you live in an agricultural area or if your neighbors spray their lawns, automotive exhaust, and chemical contaminants from your workplace. You do not want these substances in your home.

If you don't like walking around barefoot, invest in a funky sock collection or comfortable slippers. And don't be shy about asking guests and visitors to remove their shoes before entering your home. The more people encounter and learn about shoe-free homes, the more likely they are to institute similar policies in their own. You can even provide slippers to your guests.

Find more info on keeping your home dust-, allergen- and chemical-free in "Planet Home: Conscious Choices for Cleaning & Greening the World You Care About Most."

Also, check out the article I wrote for The Daily Green about keeping your shoes off in the house.