CPAP therapy does not damage healthy lungs when used as prescribed. The pressures involved are far too low to injure normal lung tissue, and there is strong evidence that CPAP actually protects the airways in several ways. That said, specific risks do exist: contaminated equipment can introduce pathogens, a defective product line released harmful particles, and certain pre-existing lung conditions can make even modest pressures problematic. The concerns people have about CPAP and lung damage are worth unpacking, because most of them point to preventable problems rather than inherent flaws in the therapy itself.
What CPAP Actually Does to Your Lungs
A CPAP machine delivers a steady stream of air at a set pressure, typically somewhere between 4 and 20 cm Hâ‚‚O. For context, that is roughly the pressure you feel when you blow bubbles through a straw in a glass of water. The purpose is to keep your airway open during sleep so you continue breathing normally. This gentle splinting effect is the whole point of the device for obstructive sleep apnea.
Beyond just keeping the airway open, CPAP has documented benefits for lung function. The continuous pressure increases the volume of air your lungs hold at the end of each breath, which boosts oxygen reserves. It also increases traction on the trachea, which helps maintain upper airway openness, and it reduces the workload on the heart by lowering cardiac afterload.1The Egyptian Journal of Bronchology. Effect of continuous positive airway pressure on the respiratory system: a comprehensive review In animal studies, bubble CPAP applied after mechanical ventilation reduced lung injury scores and decreased protein leakage into the air sacs compared to breathing without support.2PubMed. Bubble CPAP Support after Discontinuation of Mechanical Ventilation Protects Rat Lungs with Ventilator-Induced Lung Injury So the baseline effect of CPAP on the lungs is protective, not harmful.
Pneumothorax and Pressure-Related Injury
The fear that CPAP could physically rupture lung tissue comes from a real phenomenon called barotrauma, where excessive pressure over-inflates the tiny air sacs in the lungs and causes air to leak into the chest cavity. This is a recognized complication of mechanical ventilation in hospitals, where pressures are often much higher than what a home CPAP delivers. The question is whether the low pressures used for sleep apnea carry the same risk.
In the general population of CPAP users, pneumothorax is extremely rare. Case reports do exist, though. One documented case involved a 72-year-old man with chronic obstructive pulmonary disease who developed pneumothorax after four months of using an auto-adjusting PAP device set between 4 and 8 cm Hâ‚‚O. He experienced sudden severe shortness of breath at night and ultimately needed surgical repair.3PubMed Central. Pneumothorax Induced by Automatic Positive Airway Pressure Therapy for Obstructive Sleep Apnea: A Rare Case Report and Review of the Literature What stands out is that even these modest pressures were enough to cause trouble in someone whose lung tissue was already compromised by COPD.
The earliest clinical data on CPAP-related barotrauma came from neonatal medicine. A review of infants with respiratory distress syndrome found pneumothorax in about 20% of babies receiving CPAP, compared to 11% in similar infants who were not. The researchers concluded that the distending pressure created excessive stretching of the air sacs, and they recommended lowering the pressure sooner in the course of treatment.4Pediatrics. Pneumothorax and Pneumomediastinum in Infants With ldiopathic Respiratory Distress Syndrome Receiving Continuous Positive Airway Pressure Infant lungs are fundamentally different from adult lungs, so this finding does not translate directly. But it illustrates the principle: when lung tissue is fragile, even low pressures demand caution.
For an adult with normal lungs, the pressures used in sleep apnea therapy are well below any threshold for barotrauma. The risk concentrates in people who have underlying lung disease, particularly conditions that create weak spots in the lung tissue like COPD, emphysema, or a history of blebs (small air-filled blisters on the lung surface). If you have one of these conditions and use CPAP, your sleep specialist should be factoring that into your pressure settings.
Infections from Contaminated Equipment
The more realistic lung risk from CPAP has nothing to do with air pressure and everything to do with hygiene. A CPAP setup involves a mask, tubing, a humidifier chamber, and a filter. Warm, moist air flows through this system every night. If you never clean it, you are building a habitat for bacteria and fungi right next to your face.
A striking case report described a 48-year-old man with severe sleep apnea who had never cleaned his CPAP equipment in five years. He developed Pneumocystis jirovecii pneumonia, an infection usually seen in people with severely weakened immune systems. The organism was identified in his lung fluid, his CPAP mask, and the air tubing. He was not immunocompromised, meaning the sheer microbial load from the neglected equipment was likely enough to cause disease in someone with a working immune system.5PubMed Central. Pneumocystis jirovecii pneumonia presenting as a solitary pulmonary granuloma due to unclean continuous positive airway pressure equipment: a case report
Pseudomonas aeruginosa, a waterborne bacterium that thrives in humid environments, is another pathogen that can colonize poorly maintained CPAP gear. Because the humidifier chamber and tubing stay damp for hours at a time, the conditions are ideal for Pseudomonas growth, especially in immunocompromised patients or those with concurrent lung diseases like COPD.6PubMed Central. Pseudomonas Unmasked: Poor Continuous Positive Airway Pressure (CPAP) Hygiene Leads to a Case of Pseudomonas Pneumonia
Beyond acute infections, contaminated equipment can trigger hypersensitivity pneumonitis, an inflammatory lung reaction caused by repeated inhalation of organic antigens like mold spores. At least one case report documented a sleep apnea patient whose hypersensitivity pneumonitis was directly aggravated by unclean CPAP equipment.7Wiley Online Library. Hypersensitivity pneumonitis due to unclean continuous positive airway pressure equipment This type of immune-mediated lung inflammation can cause cough, shortness of breath, and if chronic, scarring of the lung tissue. It is not an infection per se but an overreaction by the immune system to mold or fungal particles being blown into the lungs night after night.
The common thread in all of these cases is neglect. Regular cleaning of the mask, tubing, and humidifier reservoir is a straightforward way to prevent any of these outcomes. Most manufacturers recommend daily emptying and weekly washing of the water chamber, along with regular replacement of filters and tubing.
The Water You Put in Your Humidifier Matters
Many CPAP users fill their humidifier chamber with tap water and think nothing of it. This is riskier than it sounds. A CDC survey found that a substantial portion of people using home medical devices like CPAP machines, humidifiers, and vaporizers were using unsterile water. The agency noted that studies have demonstrated measurable concentrations of nontuberculous mycobacteria, concentrated minerals, and other contaminants in aerosols from such devices, underscoring the need for distilled or sterilized water.8Emerging Infectious Diseases. (Mis)perception and Use of Unsterile Water in Home Medical Devices, PN View 360+ Survey, United States, August 2021
Tap water contains minerals, chlorine byproducts, and trace amounts of microorganisms. When that water is heated in a CPAP humidifier and converted into vapor, those contaminants become aerosolized and delivered directly into your airways for hours. Distilled water eliminates the mineral and microbial content. It costs a few dollars at any grocery store and is the single easiest step you can take to reduce your exposure to unnecessary airway irritants.
The Philips Foam Recall
In June 2021, Philips Respironics recalled millions of CPAP, BiPAP, and ventilator devices because the polyurethane foam used for sound dampening inside the machines was degrading. The foam broke down into particles that could enter the airflow path, and the degradation process released volatile organic compounds including toluene diisocyanate isomers and diethylene glycol, substances with potential irritant and toxic effects on the airways.9PubMed Central. Health risks related to polyurethane foam degradation in CPAP devices used for sleep apnoea treatment
This was a manufacturing defect, not a risk inherent to CPAP therapy. But it affected a huge number of users, many of whom had been unknowingly inhaling degraded foam particles for months or years before the recall. Case reports have since documented interstitial lung disease associated with this foam inhalation, where patients developed respiratory symptoms and sediment was found in their tubing systems.10PubMed Central. There Was Something in the Air: A Case of Interstitial Lung Disease Associated With Continuous Positive Airway Pressure (CPAP) Foam Degradation and Inhalation Syndrome The recall created understandable anxiety about CPAP safety in general, but the issue was specific to the Philips DreamStation line and similar models using that particular foam. Devices from other manufacturers were not affected.
If you still have an unreplaced recalled device, the fix is simple: contact Philips for a replacement or switch to a different brand. The broader lesson is that CPAP machines are regulated medical devices with components that matter. Checking for recalls and replacing worn parts on schedule is part of safe long-term use.
Humidification and Airway Inflammation
Even when the equipment is clean and the water is distilled, the question remains whether blowing pressurized air into your nose all night irritates the airway lining. The answer depends largely on whether that air is humidified.
A study of healthy volunteers found that using CPAP without humidification at a pressure of 12.5 cm Hâ‚‚O caused a significant increase in inflammatory markers in nasal wash fluid compared to humidified CPAP at the same pressure. About 70% of participants in the non-humidified group experienced at least one nasal symptom. Critically, the humidified group showed no significant difference in inflammatory markers compared to their baseline measurements, suggesting that properly humidified CPAP air does not provoke an inflammatory response in the nasal passages.11PubMed Central. Effect of humidified versus nonhumidified CPAP on inflammatory response and nasopharyngeal symptoms in healthy participants
The mechanism behind this is straightforward. Dry air strips moisture from the airway lining, concentrating the thin mucus layer and triggering an inflammatory cascade. Research on airway physiology has shown that when dry air contacts the mucus-lined surfaces, the resulting osmotic stress can activate neural pathways and promote inflammatory marker secretion.12PubMed Central. Mouth breathing, dry air, and low water permeation promote inflammation, and activate neural pathways, by osmotic stresses acting on airway lining mucus Adding humidification neutralizes this drying effect and keeps the mucosal lining closer to its natural state. If your CPAP machine has a heated humidifier and you are not using it, you are choosing the more irritating option for no benefit.
Aerophagia and Its Indirect Lung Connections
One of the most common CPAP complaints has nothing to do with the lungs directly but can create downstream concerns. Aerophagia, or swallowing air, happens because CPAP increases pressure in the upper airway, and some of that air gets diverted into the esophagus and stomach rather than the lungs. This causes belching, abdominal bloating, and flatulence. In a questionnaire study, flatulence scores increased significantly during CPAP use, and about 10% of patients who abandoned CPAP therapy did so specifically because of gastrointestinal symptoms.13PubMed Central. Gastrointestinal symptoms and CPAP-related aerophagia: a questionnaire study
The indirect lung concern here is micro-aspiration. When the stomach fills with swallowed air and the lower esophageal sphincter is under pressure, there is a theoretical risk that stomach contents could reflux upward and be aspirated into the lungs. This is more of a concern for people who already have gastroesophageal reflux disease. In practice, aspiration events from CPAP-related aerophagia are not well documented as a significant clinical problem, but people with persistent reflux symptoms while using CPAP should mention it to their provider. Adjusting the pressure downward or switching to a bilevel device that uses lower pressure during exhalation can help reduce air swallowing.
Treatment-Emergent Central Sleep Apnea
Some people who start CPAP for obstructive sleep apnea develop a new and different pattern: their brain temporarily stops sending the signal to breathe. This is called treatment-emergent central sleep apnea, and it occurs in a subset of CPAP users, often early in treatment. The leading theory is that CPAP increases tidal volume enough to shift the body’s carbon dioxide levels, which disrupts the brain’s breathing control loop.14PubMed Central. Treatment-emergent central sleep apnea resolves with lower inspiratory pressure
This is not lung damage in the structural sense, but it does mean the lungs temporarily stop being ventilated during these central apnea events. For most people, this pattern resolves on its own within a few weeks to months as the body adjusts. When it persists, lowering the inspiratory pressure or switching to an adaptive servo-ventilation device are standard approaches. If you start CPAP and notice your sleep quality gets worse rather than better, or you wake up gasping in a way that feels different from your original apnea, treatment-emergent central apnea is worth investigating with a follow-up sleep study.
Why Fear of CPAP Can Be More Dangerous Than CPAP Itself
An underappreciated dimension of this question is that fear of lung damage leads some people to avoid or abandon CPAP therapy altogether, which creates its own health consequences. Untreated obstructive sleep apnea is associated with elevated risks of high blood pressure, heart attack, stroke, and type 2 diabetes. The intermittent oxygen drops from apnea events also create their own form of lung stress through repeated cycles of low oxygen and reoxygenation.
Claustrophobic tendencies play a significant role in non-adherence. A study found that people who scored high on a CPAP-related fear and anxiety scale were over five times more likely to use their CPAP less than four hours per night in the first week compared to people with lower anxiety scores.15PubMed Central. Claustrophobic Tendencies and Continuous Positive Airway Pressure Therapy Non-adherence in Adults with Obstructive Sleep Apnea Four hours per night is the commonly used minimum threshold for clinical benefit. Falling below it means accepting the cardiovascular and metabolic risks of poorly treated sleep apnea.
If anxiety about potential lung harm is part of what keeps you from using your machine consistently, the evidence should be reassuring rather than alarming. The lungs are not fragile organs that crumble under low-pressure airflow. They handle far greater pressure swings during a hard cough or vigorous exercise. The real risks are peripheral to the therapy itself: dirty gear, unsterile water, and a single manufacturer’s defective product. All of these are manageable with basic maintenance habits.
Ozone and UV CPAP Cleaners
A small industry of aftermarket devices claims to sanitize CPAP equipment using ozone gas or ultraviolet light. These products are marketed as a convenient alternative to hand-washing your mask and tubing. The FDA has repeatedly warned that no such ozone or UV cleaning device has received FDA authorization, and the agency has expressed concern that ozone residues left inside the CPAP circuit could themselves irritate the airways. The irony is real: a product marketed to protect your lungs from dirty equipment may introduce a new irritant that would not have been there with plain soap and water.
If you are concerned enough about contamination to buy a dedicated cleaner, that concern is better directed toward the fundamentals. Wash the mask cushion daily with mild soap. Wash the tubing and humidifier chamber weekly. Replace disposable filters monthly and reusable filters every six months. Use distilled water. These steps take a few minutes and address every hygiene-related lung risk that has actually been documented in the medical literature.