I'm not sure which is worse: seeing that distressing brown layer of smog that sometimes hovers in the air, or not seeing it.

Personally, seeing smog always leaves me feeling somewhat helpless. It seems to defeat all the effort I put into trying to lead a healthier, fitter life. After all, it's hard to avoid breathing just because it's particularly smoggy outside.

But it turns out that indoor pollution—a menace that is pretty much invisible—is two to five times worse than the air quality outside.

According to the Environmental Protection Agency, indoor air quality is worsened by candles, cleaning products, paint, furniture, even our shoes. They've posted a helpful guide on their website.

The best part? I was thrilled (and relieved) to see that most steps are easy to work into daily life. Here are several ways to reduce unhealthy particulates inside and make your home healthier.

Easiest Improvements

• Get into the habit of leaving your shoes, which track in dust, pollen, and pesticides, at the door.
• Switch to soy or beeswax candles because the petroleum-based paraffin wax from regular candles produces soot. (And while you're at it, skip smoky incense.)
• Use green cleaning products, because traditional products use harsh chemicals that can leave you dizzy and nauseous, or give you a sore throat or other ailments.
• Run a fan when you're taking a shower to keep toxic mold from spreading.
• Open your windows to release particulates that have built up inside.
• Replace a vinyl shower liner with nylon or cotton, because vinyl releases pollutants.
• Cut down on dry cleaning as it releases carcinogenic solvents; or use an eco-friendly dry cleaning service.
• Wash bedding weekly, and use allergen-proof mattress and pillow covers to starve dust mites.

Next Steps

• Replace your carpets with hard surfaces, which don't harbor dust, pollen, animal dander, or other allergens.
• Use low VOC-paints, because traditional paint releases toxins for up to a year.
• If you have a fireplace or wood-burning stove, get the chimney swept on a regular basis.
• Opt for solid wood furniture when possible, because furniture made from MDF and particle-board can contain formaldehyde.
• Get a radon kit and test the levels; radon is a leading cause of lung cancer.