It’s carried out using a device called a spirometer, which is a small machine attached by a cable to a mouthpiece.

Why spirometry is carried out

Spirometry can be used to help diagnose a lung condition if you have symptoms, or if your doctor feels you’re at an increased risk of developing a particular lung condition.

For example, spirometry may be recommended if you have a persistent cough or breathlessness, or if you’re over 35 and smoke.

Conditions that can be picked up and monitored using spirometry include:

• asthma – a long-term condition where the airways become periodically inflamed (swollen) and narrowed
• chronic obstructive pulmonary disease (COPD) – a group of lung conditions where the airways become narrowed
• cystic fibrosis – a genetic condition where the lungs and digestive system become clogged with thick, sticky mucus
• pulmonary fibrosis – scarring of the lungs

If you’ve already been diagnosed with 1 of these conditions, spirometry may be carried out to check the severity of the condition or see how you’re responding to treatment.

Spirometry is also a standard test for people being considered for surgery, or to check the general health of people who have other conditions, such as rheumatoid arthritis.

Preparing for the test

You’ll be seated during the test and a soft clip will be placed on your nose to stop air escaping from it. 

The tester will explain what you need to do, and you may be asked to have a few practice attempts first.