How to Properly Clean and Disinfect a Spirometer

Cleaning a spirometer properly involves a layered approach: using disposable in-line filters and mouthpieces for every patient, washing hands before and after each test, and routinely disinfecting reusable tubing, sensors, and surfaces according to the manufacturer’s specific instructions. The process sounds straightforward, but the details matter because spirometers sit at an unusual intersection of infection risk and measurement sensitivity. Aggressive cleaning with the wrong chemical can throw off calibration, while skipping steps can leave behind viable bacteria in tubing and connection points.

Why Spirometer Hygiene Matters

Patients blow forcefully into spirometers during lung function testing, generating aerosol droplets that can carry bacteria, viruses, and fungi. Contamination has been documented in mouthpieces, connection tubing, and the internal chambers of water-sealed devices.¹ Documented cases of cross-infection from pulmonary function labs are rare, but the potential is real enough that every major professional society addresses it in their guidelines.² Infrastructure, daily patient volume, and disinfection practices all play a role in whether transmission occurs.³

The risk isn’t limited to what the patient breathes through. Patients touch handheld spirometers, chair arms, noseclips, and the surfaces around the testing station. The 2019 American Thoracic Society and European Respiratory Society (ATS/ERS) technical statement specifically calls out both direct contact with mouthpieces and valve surfaces and indirect aerosol transmission into the room air between maneuvers.² In other words, cleaning the spirometer itself is only part of the picture. You also need to think about hands, gloves, and the surrounding environment.

The First Line of Defense: Disposable Filters and Mouthpieces

In most modern pulmonary function labs, the single most effective infection control measure is a disposable in-line bacterial/viral filter placed between the patient’s mouth and the spirometer’s internal sensor. These filters are now standard practice in most facilities, and the mouthpiece is typically built into the filter assembly, so both are discarded together after each patient.² This setup dramatically reduces how much biological material ever reaches the spirometer’s reusable parts.

Not all filters perform equally, though. A study comparing six commercially available in-line filters found significant differences in how well they removed bacteria under extreme challenge conditions. Four of the six achieved 100% bacterial removal efficiency at a moderate challenge level, but one dropped to about 43% efficiency under the same conditions.⁴ The filters also differed sharply in their threshold, meaning the bacterial load at which they began to fail. The best-performing filters held up at challenge levels a thousand times higher than the worst performers. A separate evaluation of filter efficiency found that volunteers breathing through filters produced a calculated removal efficiency of 99.9%, with no bacterial growth detected on collection plates behind the filter during normal breathing.⁵

The practical takeaway is that a high-quality filter does the heavy lifting, but choosing a cheap or poorly tested filter can leave a gap in protection. If your facility purchases filters, it is worth checking whether independent bacterial removal data exists for the specific brand and model.

Where Contamination Actually Concentrates

Among the various components of a spirometer, mouthpieces carry the greatest risk of bacterial contamination, with one survey finding contamination on 92% of sampled mouthpieces. Proximal tubing, the section closest to the patient, was contaminated about half the time. No contamination was found from samples taken deeper within the equipment itself.⁶ This gradient makes sense: the mouthpiece is the only part that directly contacts the patient’s lips, tongue, and exhaled breath at full force, and the tubing immediately downstream catches whatever the mouthpiece doesn’t.

Because contamination tapers off sharply as you move away from the patient end, the cleaning protocol follows the same gradient. Mouthpieces are always single-use. Proximal tubing and any reusable breathing valve surfaces get the most frequent cleaning. Internal spirometer components rarely need disinfection if filters are used consistently.

Hand Hygiene and Gloves

The ATS/ERS guidelines are explicit: the operator must wash hands or use an approved hand sanitizer before contact with each new patient, and hands must be washed again immediately after handling mouthpieces, tubing, breathing valves, or interior spirometer surfaces.² Wearing disposable gloves does not replace handwashing. If gloves are used, a new pair is required for each patient. Many labs also give the patient a hand disinfectant gel or wipe when they first sit down, because patients will be touching the spirometer, the chair, and other shared surfaces during testing.

This level of hand hygiene discipline often gets shortchanged in busy labs, but it matters. Cross-contamination through the operator’s hands is one of the easier transmission routes to prevent and one of the easiest to let slip during a packed clinic schedule.

Cleaning and Disinfecting Reusable Parts

Every spirometer manufacturer is supposed to describe acceptable methods of cleaning and disinfecting their equipment, including recommended chemicals and concentrations, as well as safety precautions for the operator.² Following those instructions is genuinely important, not a legal formality, because different spirometer designs use different sensor types and materials that react differently to cleaning agents.

The general process for reusable components, particularly tubing, reusable flow sensors, and breathing valve assemblies, follows a two-stage logic familiar from any medical device reprocessing:

Cleaning first: Physical removal of saliva, mucus, and visible soil. This usually means rinsing with warm water and a mild detergent, then wiping or brushing accessible surfaces. Cleaning must come before disinfection because organic material left on a surface can shield bacteria from disinfectant chemicals. Research on endoscope reprocessing, which follows the same principle, has shown that enzymatic detergents remove significantly more biological residue than non-enzymatic cleaners.⁷ Whether your spirometer manufacturer recommends an enzymatic or standard detergent, the key point is that skipping the cleaning step and jumping straight to disinfection leaves organic residue behind, reducing the effectiveness of whatever disinfectant you apply.
Disinfection second: After cleaning, reusable components are typically soaked in or wiped with a chemical disinfectant at the concentration and contact time the manufacturer specifies. Common agents include quaternary ammonium compounds, dilute bleach solutions, and certain alcohol-based solutions, but the correct choice depends on the specific device. After the contact time, components are rinsed with clean water to remove chemical residue and then thoroughly air-dried before reassembly.

How often you repeat this cycle depends on patient volume. In a high-throughput lab, reusable tubing may be disinfected at the end of each session or testing day. In lower-volume settings, it may be less frequent, but all disposable items, including filters, mouthpieces, noseclips, and gloves, are always discarded at the end of the testing session.²

Why Chemical Choice Matters More Than You’d Think

Chemical disinfection of spirometer parts should be used with caution. Heat sterilization and cold chemical sterilization can both damage flow sensors, tubing, and seals if the wrong method or concentration is used.⁶ A more practical review of infection control for lung function equipment put it plainly: disinfection and sterilization can be achieved by a variety of methods, but chemical methods should be used with caution.⁸

Glutaraldehyde, for example, is a powerful high-level disinfectant used in some healthcare settings, but it can corrode metal flow sensors and degrade certain plastics and rubber seals. Bleach at concentrations higher than the manufacturer’s recommendation can do the same. Even alcohol-based wipes, while convenient for external surfaces, may not be compatible with the polymer housings on every device. The safest approach is to check the spirometer’s user manual for a list of approved disinfectants and stick to those. If the manual is vague or outdated, contacting the manufacturer directly for current recommendations is well worth the effort.

The Calibration Problem

Here’s a complication that doesn’t get enough attention: repeated cleaning and disinfection can gradually alter the measurement accuracy of certain spirometer sensors. A study of portable spirometers with pneumotachometer-style flow tubes found that the sensors remained accurate for roughly five to nine disinfection cycles but began to drift toward inaccuracy after even the first disinfection. After ten disinfection cycles, all the pneumotachometers had become inaccurate according to ATS criteria.⁹

This doesn’t mean you should skip disinfection to preserve accuracy. It means you should recalibrate after every disinfection cycle, or at least verify calibration with a known-volume syringe. In the study, the researchers developed a combined cleaning-and-calibration protocol specifically to address this drift. If your spirometer uses a pneumotachometer (a wire mesh or screen that senses flow by measuring pressure differences), be aware that cleaning agents and physical handling can subtly change the mesh’s resistance, throwing off readings. Turbine-style spirometers are generally less sensitive to this issue, but calibration checks are still good practice regardless of the sensor type.

For labs running high patient volumes, this creates a real tension. You want to clean thoroughly and often for infection control, but every cleaning cycle nudges the sensor slightly out of spec. The solution isn’t to clean less; it’s to budget time for verification after each cleaning and to replace consumable sensor elements according to the manufacturer’s schedule.

Additional Precautions for High-Risk Patients

The general cleaning protocol described above applies to the majority of patients walking into a pulmonary function lab. But when a patient is known to be infectious, particularly with tuberculosis, drug-resistant organisms, or other airborne or droplet-spread pathogens, or when a patient is severely immunocompromised, additional precautions are warranted. A practical infection-control review noted that for such patients, measures like using a barrier filter become especially important.⁸

In practice, “additional precautions” usually includes some combination of the following:

Dedicated equipment: Using a spirometer reserved for high-risk patients, or scheduling these patients at the end of the day so a full disinfection cycle can follow.
Room ventilation: Testing in a negative-pressure room or a well-ventilated space, since aerosols generated between maneuvers travel into the ambient air and can linger.
Enhanced disinfection: Full disinfection of all reusable components immediately after the session, rather than at the end of the day, using a higher-level disinfectant if the manufacturer permits.
Operator protection: Respiratory protection (N95 mask or equivalent) for the technician, in addition to standard gloves and hand hygiene.

Local infection control policies vary, and the ATS/ERS guidelines note that additional steps may be required by institutional policy beyond what the general standard recommends.² If you work in a facility that sees a meaningful number of patients with active TB or multidrug-resistant infections, it’s worth having a written protocol for those encounters rather than making it up on the spot.

Cleaning a Home or Personal Spirometer

Home spirometers, increasingly common with the rise of telehealth and remote monitoring for conditions like asthma, COPD, and post-transplant care, present a different cleaning scenario. Because these devices are typically used by a single person, the cross-infection risk is minimal. The main concern shifts to keeping the device free from mold, dust, and dried secretions that could clog the sensor and produce inaccurate readings.

Most personal spirometers come with manufacturer instructions that involve rinsing the mouthpiece and any detachable tubing in warm soapy water, allowing everything to air-dry completely, and occasionally wiping down the device body. Some home devices use disposable mouthpieces or turbines that are replaced periodically rather than cleaned. The “air-dry completely” step is easy to skip and genuinely important: moisture trapped inside a flow sensor creates an ideal environment for mold growth, which can both degrade readings and potentially be inhaled during the next test.

If you share a personal spirometer with another household member, the infection control considerations become more similar to a clinical setting. At minimum, each person should use their own mouthpiece, and the tubing should be cleaned between users. A disposable in-line filter is an option if available for your device model, though many consumer-grade spirometers do not accommodate standard clinical filters.

Common Mistakes and Overlooked Steps

Even in well-run labs, a few errors come up repeatedly. One is failing to clean before disinfecting. Disinfectant chemicals work on surfaces, not through layers of dried mucus. If organic residue remains on tubing after a hasty rinse, the disinfectant contacts the residue rather than the surface underneath, leaving viable organisms behind. The same principle has been demonstrated in endoscope reprocessing: thorough pre-cleaning is a prerequisite for effective disinfection.⁷

Another common issue is inadequate drying. Reassembling a spirometer while the tubing or sensor is still wet can introduce moisture into the device body, promote microbial growth between uses, and, in the case of pneumotachometer screens, alter flow resistance and skew readings. Thorough air-drying after every cleaning cycle is a non-negotiable step that gets shortened when the next patient is already waiting.

A third mistake is assuming that filters eliminate the need for any other cleaning. Filters are highly effective, but they do not protect the exterior of the device, the chair, the noseclip (if reusable), or the operator’s hands. And if a filter develops a small leak or is seated improperly, exhaled material can bypass it entirely and reach the internal sensor. Filters are one layer in a multi-layer system, not a substitute for the other layers.

Finally, some labs neglect to track the number of disinfection cycles their reusable components have undergone. As noted in the calibration discussion, sensor accuracy can drift with repeated cleaning. Keeping a simple log of when tubing and sensors were last disinfected and when they were last calibration-verified helps catch accuracy problems before they affect patient results.

How Facility Layout Affects Contamination Risk

The physical setup of the testing space matters more than many labs realize. In a small, poorly ventilated room with patients tested back-to-back, aerosol droplets generated during forced exhalation linger in the air and settle on nearby surfaces. The ATS/ERS statement specifically notes that indirect transmission occurs via aerosol droplets expelled into the air of the testing room between maneuvers, not only through direct contact with the mouthpiece.² Room ventilation, spacing between test stations in labs with multiple setups, and regular wiping of nearby hard surfaces all factor into overall infection control, even though none of these involve the spirometer itself.

In facilities that tested patients during respiratory disease outbreaks, some moved to testing in open or well-ventilated areas, increased time between appointments to allow air clearance, and added surface decontamination protocols for the testing station between patients. These environmental measures complement the device-level cleaning steps outlined above and are worth building into any lab’s standard operating procedures.