If you use synthetic air fresheners in your car and/or living space, you should know that you're likely increasing risk of developing a variety of health problems. Headaches, earaches, depression, an irregular heart beat, and diarrhea in babies are just a few of many health challenges that have been linked to regular use of synthetic air fresheners.

A report that was released in September of 2007 by the Natural Resources Defense Council found that 12 of 14 brands of common household air fresheners contained phthalates. Phthalates are chemicals that are used to prolong the length of time that scented products maintain their fragrance. Regular exposure to phthalates can increase your risk of experiencing endocrine, reproductive, and developmental problems. Amazingly, some of the brands that tested positive for phthalates did not include phthalates on their lists of ingredients; some of these brands were even labeled as being "all-natural" and "unscented."

In response to this study, the National Resources Defense Council produced the following list that indicates the presence or absence of phthalates in common air fresheners:

Highest levels of phthalates:

Walgreens Air Freshener Spray (removed from shelves)

Walgreens Scented Bouquet Air Fresheners (removed from shelves)

Walgreens Solid Air Fresheners (removed from shelves)

Ozium Glycolized Air Sanitizer

Medium levels of phthalates:

Air Wick Scented Oil

Febreze NOTICEables Scented Oil

Glade Air Infusions

Glade PlugIn Scented Oil

Oust Air Sanitizer Spray

Low levels or no phthalates detected:

Citrus Magic

Febreze Air Effects Air Refresher

Lysol Brand II Disinfectant

Oust Fan Liquid Refills

Renuzit Subtle Effects

Please note that having no phthalates does not make synthetic air fresheners safe to use in your car or home. The vast majority of synthetic air fresheners emit significant amounts of terpene, a volatile organic compound that can react with naturally occurring ozone to create formaldehyde. Ozone, a form of oxygen, exists at some level both indoors and outdoors, so formaldehyde formation is practically inevitable wherever synthetic air fresheners are used. Indoor environments that tend to have elevated levels of ozone include those where photocopiers and ozone-generating air purifiers are used.

Why should you be concerned about exposure to formaldehyde? Formaldehyde is classified as a human carcinogen by the International Agency for Research on Cancer.

Given all of the above, it's not surprising that a study that was published in a 2007 issue of the American Journal of Respiratory and Critical Care Medicine indicates that regular use of sprays can increase your risk of developing asthma by 30 to 50 percent. This study was performed by the European Community Respiratory Health Survey, and collected data from 3,500 people in 10 European countries.

Clearly, your health is best served by minimizing exposure to synthetic air fresheners and other synthetic products that are designed to emit a prolonged artificial scent.

Here are some simple and natural ways of keeping your car and living space smelling fresh without using chemical-laden air fresheners:

Open your windows - even just a crack during cold weather - for at least 30 minutes a day. Weather permitting, it's best to keep your windows open all the time, assuming that you don't live in a heavily polluted area. Sprinkle baking soda on carpets before you vacuum. Keep a box of baking soda open in the room. Keep natural (preferably organic) potpourri in a bowl out in the open, or put into little sachets to keep around the house. Maintain a friendly gathering of indoor plants in your living and work spaces. Take the garbage and compost out every day.

Please consider sharing this information with friends and family members who use synthetic air fresheners in their cars, homes, and work places. And if you have any other ideas on how to keep these areas smelling fresh without using synthetic chemicals, please consider adding them to the comments section below. Thank you.