Everything You Need to Know About Exhalation Valves

Everything You Need to Know About Exhalation Valves

What are they? What do they do?

January 21, 2021 | Published by O2

Since COVID-19 first entered into our collective consciousness, we’ve all been required to wear a mask at some point or another. Whether it’s while shopping for groceries or even while walking outside, masks have become a part of our everyday existence. Through public health education campaigns, we’ve learned that wearing a mask can help save lives. We wear them to protect ourselves, but just as importantly, we wear them to protect others. Masks, according to the CDC (Center for Disease Control and Prevention), help prevent you from spreading respiratory droplets to others, which is the main way that COVID-19 spreads. In order to protect others, masks and respirators need to provide two-way protection, meaning they need to filter both the air you breathe in and the air you breathe out.

There are many different types of masks with tons of different features, such as multiple layers, built-in filters, and water-resistant fabrics. One common feature found on many masks and respirators is the exhalation valve. The main role of exhalation valves on a respirator is to reduce breathing resistance when exhaling. They are designed to allow exhaled air to exit the respirator and then close tightly during inhalation, so inhaled air enters only through the filter. They also help to regulate the temperature and humidity inside the respirator, allowing those that wear glasses to avoid the dreaded foggy lenses.

Years before the onset of the COVID-19 pandemic, our founders Peter and Rich set out to design a respirator that would protect its wearer’s lungs from harmful air pollution. In order to create a respirator that was comfortable, breathable, and that could be worn for extended periods of time, they designed the O2 Curve with two exhalation valves. When breathing is normal, much of the air you breathe out will pass through the Curve’s filter, but when breathing is heavier some unfiltered air will exit through the exhalation valves.

Some governments, local health authorities, and airlines have issued guidelines that recommend against the wearing of masks and respirators with exhalation valves as they can potentially expose those around you to your exhaled particles, meaning they do not offer two-way protection. 

As research on the use of face coverings has increased over the course of the pandemic, we’ve learned that different types of masks have varying degrees of effectiveness. For example, simple two-layer cloth masks, while still more effective than not wearing a mask at all, provide less protection than a surgical mask or respirator. It’s important to remember that cloth and surgical masks are primarily designed to protect others, not the wearer. For example, doctors wear surgical masks mainly to protect their patients. To protect themselves, they would wear a respirator; to protect both themselves and their patients, they would wear both a respirator and a surgical mask.

As mask mandates and recommendations became part of the new normal, we knew we needed to adapt to this changing environment and come up with a way to give the Curve two-way protection. We quickly designed the Surgical Mask Adapter, which clips on to the front of the Curve’s shell, and allows a surgical mask to be worn over top of the Curve, providing the wearer with two-way protection. This solution helps prevent any unfiltered droplets that might be expelled through the Curve’s exhalation valves, stopping them in their tracks.

As the pandemic raged on, we came up with a second solution. In order to provide more options for two-way protection we designed Valve Plugs that plug the Curve’s exhalation valves, forcing all inhaled and exhaled air through the Curve’s electrostatic filter. When worn with our Crystal Clear Shell this allows anyone looking at your Curve to see the filtration it provides. Together, the Valve Plugs and Crystal Clear Shell make the Curve compliant with most regional and travel guidelines. It’s important to check with your local authority as regional regulations and requirements may vary. We also recommend using our Max Air Filters when wearing Valve Plugs with your Curve, as this will help maintain the Curve’s superior breathability.

If you’re looking for the maximum protection from your face covering for both you and those around you, the O2 Curve worn with Valve Plugs is the answer.


6 thoughts on “Everything You Need to Know About Exhalation Valves

  1. Great information. I have been using a O2 curve for almost 9 months. It works well. The only thing is that condensation occurs inside the curve especially in a colder environment such as outdoor. After a while the filter is soaked with condensation and make it very difficult to brief. Is there a potential improvement to that?

    1. Thanks for reading Thomas! Unfortunately condensation happens naturally when wearing the Curve, especially in colder temperatures. What we can recommend is that you try out our Max Air filters to increase your breathability while still retaining the same amount of filtration. Although this option may help with breathability purposes, it is still possible for condensation to occur.

      1. I enjoy the product for the most part, however I live in Chicago so it’s cold often and whenever I return home, my filter is completely soaked. Although the condensation is annoying, it is tolerable given the design and protection. However, is the filter still effective when it is wet?

      2. Hey there, great Q!

        The filter system works both mechanically and electrostatically, meaning the particles that are too small to be filtered physically are attracted to the charged filter, for improved filter efficiency and performance. This means that the filter will still in fact still work if it becomes moist/wet, but the electrostatic charge will just be less effective. Keep in mind that upgrading to the Max Air filters will help with condensation build-up inside of the respirator as the Max Air filters offer more breathability.

  2. How are the MAX AIR FILTERS different? Thinner? Price? Duration of effectiveness? If wet, will it regain effectiveness after dried?

    1. Hey Steve,

      The O2 Max Air filter is thinner and 3x more breathable than our regular filter, allowing for 125CFM of airflow. This lighter filter material maintains an efficiency of greater than 99% with particle sizes down to 0.1 µm using a flow rate of 32L/min. Given the lightweight filtration system it is recommended to change your Max Air filter daily to ensure maximum protection.

      Our filters work both mechanically and electrostatically. Particles that are too small to be filtered physically are attracted to the charged filter. The filter will still work if it gets moist but it’s effectiveness may be affected as the moisture will lessen the electrostatic charge. It is not recommended to use the filter if it has become completely saturated or once dried, after having been soaked.

      Check out the filters here: Max Air Filters

      Hope this helps!

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