Spirometry is a simple test used to help diagnose and monitor certain lung conditions by measuring how much air you can breathe out in one forced breath.

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

Spirometry may be performed by a nurse or doctor or it may be carried out during a short visit to a hospital or clinic.

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.