top of page

Oxygen Mask Dangers

There are many devices designed to deliver oxygen to patients. When used properly, each oxygen delivery device can be an effective tool to help improve a patient’s oxygen levels in his or her blood. In this article, we will compare two delivery devices: the nasal cannula and oxygen mask.


The nasal cannula is the most common oxygen delivery device used today. The cannula is comprised of two prongs that fit gently into the nostrils, with smaller tubing that loops over the ears and under the chin with a sliding nut that snugs the cannula in place so that it doesn’t dislodge. The standard adult nasal cannula can run as low as ½ liter per minute to as much as 6 liters per minute. As a rule of thumb, the nasal cannula delivers 24% of oxygen at one liter, with an increase of 4% of oxygen for each additional liter flow. So, at 2 liters, the cannula would deliver 28%, at 3 liters, the cannula would deliver 32%, and so on up to 6 liters. This rule is an estimate at best as respiratory rate and depth of breathing affect the percentage of oxygen being delivered to the patient. The nasal cannula comes in a variety of configurations for different age groups and flow levels. For the purposes of comparison in this article, we will be discussing the standard adult cannula, which is the most commonly used.


The oxygen mask is made from a soft polymer that fits over both the nose and mouth. There are very small holes on each side of the mask for ventilation purposes. The oxygen tube connects to the front lower portion of the mask. There is an elastic strap which slips over the head to hold the mask into position. The recommended flow rate range of the simple mask is 6 to 10 liters per minute and the oxygen percentages vary from 40% to 60%. A minimum flow of 6 liters is necessary to help “flush” out the patients exhaled carbon dioxide which passes through the small holes on the sides of the mask previously mentioned.


As far as comfort, the nasal cannula is more comfortable than the simple mask; it is smaller, lighter and cooler to wear than the mask. The oxygen mask is bulkier and warm on the face. Some patients get a feeling of claustrophobia while wearing the oxygen mask.

More important than comfort is the clinical functionality of the nasal cannula over the oxygen mask. If you have been diagnosed with Chronic Obstructive Pulmonary Disease, (COPD) more oxygen is not necessarily better. Oxygen levels for patients with COPD are effectively maintained on low flow, low dose oxygen, using 1 to 3 liters per minute, which equates to approximately 24 % to 32% oxygen. A COPD patient receiving higher percentages of oxygen, such as what the simple mask delivers, could potentially elevate their carbon dioxide levels to dangerously high levels which would be detrimental to their health. As previously noted, you cannot safely run an oxygen mask at less than 6 liters per minute because exhaled carbon dioxide would not be flushed out of the mask causing carbon dioxide levels to increase.

In review, the nasal cannula is today’s choice for delivering safe and effective oxygen to the patient with Chronic Obstructive Lung Disease. Unless you have specific circumstances and it is prescribed by your physician, the COPD patient should not wear a simple oxygen mask as it could raise your carbon dioxide levels and potentially compromise your health.

First published on



bottom of page