If you are sneezing and itching your eyes this spring allergy season, you are not alone. 2011 is shaping up to be the worst year for allergy sufferers on record.

More than 35 million American suffer from pollen allergies, according to the FDA . Every year, the United States spends $21 billion on health costs related to allergies.

A study published today in the Proceedings of the National Academy of Sciences of the USA searched for the cause of a trend towards longer allergy seasons.

Researchers found that a delayed first frost of the fall season and a lengthening of the frost-free season combined with increasing levels of carbon dioxide in the atmosphere have contributed to a longer allergy season. Longer pollen seasons increase human exposure, the duration of symptoms and severity of symptoms.

“Studies have found that not only do [plants] create more pollen, it’s more potent,” said Dr. Stanley Fineman, president-elect of the American College of Allergy, Asthma and Immunology and a practicing physician in Atlanta.

So what can you do if you are one of the millions of Americans who suffer from pollen allergies every year? Fineman gave ABC News five helpful tips:

5 Tips for Avoiding Allergies

 Get tested to find out exactly to what you are allergic.

 Consult your physician about possible treatments such as allergy shots and medication.

 Wash your hair and clothes regularly to get rid of pollen.

 If you have pets, groom them regularly because they can bring pollen indoors.

 Stay indoors as much as possible during pollen season to minimize your exposure.

Thankfully, science has been steadily improving the ability to combat pollen allergy symptoms.

“We can [now] pinpoint what triggers symptoms with specific testing, where in the past it was much more generalized,” said Fineman. “Now, it’s much more specific and accurate and sensitive. … Treatments are more targeted and allergy shots are much more effective because we know better dosages.”

(Source: WABC)