What Is Forced Expiratory Volume (FEV)?

When you apply for Social Security disability benefits, you'll need medical evidence to document the severity of your impairment. If your disability claim is based on a chronic respiratory or pulmonary disorder, the Social Security Administration (SSA) will look at your pulmonary function test results to see if your FEV measurements fall within a specific range.

But what is FEV? And what does yours need to be to prove you're disabled?

What Does Your FEV Mean?

Your "forced expiratory volume," or FEV, is the volume of air you can force from your lungs after taking a deep breath. FEV readings are generally obtained through spirometry tests (a type of lung function test).

Social Security uses FEV results to measure your pulmonary function when your disability claim is based on chronic respiratory disorders, such as:

• emphysema
• COPD
• pulmonary fibrosis
• asthma, or
• cystic fibrosis.

The lower your FEV reading, the more severe your respiratory disease is.

Spirometry Testing for FEV

The spirometry test measures the amount of air you inhale and exhale during a specific amount of time. During this test, you place a mouthpiece over your mouth, inhale deeply, and then forcefully blow out the air.

A spirometry test gives your doctor an FEV or FEV1 measurement (the amount of air exhaled in one second). It also provides an FVC measurement (total volume of air that you exhale during the test).

The results can show how much your lung function has deteriorated. And your doctor can use a spirometry test to determine how well prescribed medications work or if your respiratory condition is worsening.

For Social Security to accept that your FEV1 or FVC values are reflective of your level of disability, you must put effort into the test. If it appears that you didn't give your best effort (and the doctor giving you the test records this information), Social Security will ignore the results and might require you to take a new spirometry test at a consultative exam (CE).

Social Security will use your highest FEV1 value to assess the severity of your respiratory impairment. If your FEV1 is less than 70% of the predicted normal value, Social Security will require you to be tested again after using an inhaled bronchodilator, unless there's a medical reason you can't.

Also, pulmonary function tests must be performed when your condition is stable—not during an asthmatic attack or an acute respiratory infection—for Social Security to consider the results valid.

Understanding Social Security's FEV Tables

Social Security will check to see if your respiratory impairment is severe enough to meet (or "equal") one of the respiratory disorder listings in the "Blue Book." If your condition meets the requirements of a listing, you'll automatically qualify as disabled.

Social Security will compare your lung function to the values listed in one of three FEV1 tables. Most chronic respiratory disorders are evaluated using Table I in the respiratory listings. There are two exceptions:

• Asthma uses Table VI, and
• Cystic fibrosis uses Table VII.

All three tables list FEV1 values as the number of liters of air you can expel (breathe out) in one second. Social Security will consider you disabled if your FEV1 is less than or equal to the value in the table that corresponds with your:

• age
• gender, and
• height.

The FEV threshold is higher for taller people and for those younger than 20. But it's lower for women than it is for men.

Other Measures of Pulmonary Function

Social Security also uses "forced vital capacity" (FVC) results to determine pulmonary function. FVC measures the total amount of air you can exhale quickly and forcefully after inhaling as much as possible. The FVC requirements are listed in Table II in the respiratory listings.

Some other tests that can be used to document your lung function include:

• the arterial blood gas (ABG) test, which evaluates levels of oxygen and carbon dioxide in your blood, and
• pulse oximetry, which shows the percentage of oxygen in your blood.

What If My FEV1 or FVC Results Are Too High?

Even if your FEV1 value or other pulmonary test results don't meet the requirements of a listing, you might still qualify for disability benefits if your respiratory disorder prevents you from working. Social Security will determine what you can and can't do given your medical condition. If your breathing limitations prevent you from doing your old job, the agency will check to see if there's a less physically demanding job you can be expected to do.

Learn more about getting disability benefits because you can't work.