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Respiratory hazards, including mold, respiratory viruses, and air pollutants, such as particulate matter, which is found in air pollution emitted from various sources (e.g., cars, industrial activities) as well as wildfire smoke, pose serious threats to public health in the U.S. and globally. Exposure to such hazards may lead to the development or worsening of various respiratory and cardiovascular diseases and other chronic health conditions, including:

  • Asthma
  • Respiratory Tract Infections
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Ischemic Heart Disease

The consequences of exposure to respiratory hazards can be deadly. In the United States, between 100,000 and 200,000 excess deaths are attributable to air pollution each year, not including contribution of wildfire smoke. Globally, approximately 339,000 deaths each year can be attributed to wildfire smoke exposure alone and airborne infectious agents contribute to millions of deaths annually.

These dangers in the air we breathe raise urgent questions about how we can better protect ourselves, our families, and our communities from respiratory hazards. While the safest action may often be to remove oneself from a hazard (e.g., by leaving the affected area) or prevent the hazard from entering the air, such actions are not always possible or sufficient and increasingly, respiratory protection is used to reduce our exposures to respiratory hazards and protect against the health threats they pose. While the COVID-19 pandemic has placed a spotlight on the use of respiratory protection, questions from the public remain about when and how it should be used and which devices are appropriate for a specific hazard.

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Common Scenarios in Which Respiratory Protection may be Needed

People may be exposed to respiratory hazards in a number of situations, including emergency settings and in more routine aspects of life, such as home maintenance and hobby-related activities, but common hazards and scenarios that may call for use of respiratory protection include

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Wildfire Smoke & Air Pollution

Exposure description: Wildfire smoke and other types of air pollution expose millions of individuals to dangerous concentrations of fine particulate matter, as well as other harmful compounds, all of which can have negative health effects. Even those outside the directly impacted area may be exposed, as winds can spread particulate matter from wildfire smoke over hundreds or thousands of miles away.

User Need: When other methods for reducing exposure to wildfire smoke or air pollution (e.g., limiting time outdoors, indoor air filters) are not feasible or are insufficient, specifically during periods of extremely poor air quality, wearing a device that provides personal protection can reduce the inhalation of harmful particles. Checking air quality levels and current conditions related to wildland fires can help people determine when respiratory protection may be needed.

Device Type: A particulate respirator has the ability to protect the user from the inhalation of harmful particles but does not provide protection against dangerous vapors and gases, such as carbon monoxide.

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Exposure description: A person can be exposed to molds in a variety of scenarios. One of the most common is exposure to molds following extreme weather events, like flooding and hurricanes, which require post-disaster clean up in a water-damaged building.

User Need: Individuals exposed to molds, such as a homeowner remediating flood damage in their house, need to wear a device that provides personal protection and prevents them from inhaling potentially harmful mold spores.

Device Type: A particulate respirator has the ability to protect the user from the inhalation of mold spores.

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Respiratory viruses

Exposure description: Exposure to respiratory viruses can occur seasonally but also during outbreaks or pandemics, during which respiratory protection may play an important role in reducing the spread of a virus and associated illnesses and deaths.

User Need: Because respiratory viruses can be transmitted from person to person, an individual has the potential to be a source of the virus and at risk of being infected by others. When faced with respiratory viruses, individuals may need to wear a device that provides personal protection and/or reduces the chance that they will spread an infection to others.

Device Type: Surgical masks, barrier face coverings, and respirators can all can play a role in preventing the spread of respiratory viruses but particulate respirators are generally best suited for protecting the wearer from being infected, particularly if the virus is airborne.

How Does Respiratory Protection Work?

Fit and Filtration

Respiratory protection for particulate hazards (which include viruses, mold spores, and particulate matter in smoke but not gases or vapors) works by capturing particles onto a filtering material, reducing the number of particles that pass through the device. Fit and filtration are the main factors that influence how well respiratory protection works for a specific hazard. Understanding these factors can help individuals select and use the correct device for their exposure situation.

Filtration refers to a device’s ability to remove particles from the air as it moves through the filter material. Different devices have different filtration abilities.

Fit refers to how well a device creates a sealed barrier around the wearer’s nose and mouth. An improper fit allows leaks—rather than moving through the filtering material, air escapes through gaps around the edges of the device, potentially allowing the entrance or release of hazardous particles. These leaks most frequently occur around the sides of the device and the bridge of the nose. Facial hair is one common cause of these leaks, but other factors like face size and shape can impact how well a certain device will fit to the face.

Source Control versus Personal Protection

The COVID-19 pandemic has raised greater awareness about respiratory protection, but has also led to widespread confusion about the different purposes devices can serve—personal protection and source control—and the ability of different devices to carry out these different functions.

Some devices work as both source control and personal protection but to different degrees depending on the device, its level of fit and filtration, and the respiratory hazard.

Devices used for the purpose of source control are worn to protect other people from infectious respiratory hazards (e.g., viruses, bacteria) that the wearer may release into the environment, for example, when breathing, talking, or coughing. The use of a device for the purpose of source control is only relevant when the respiratory hazard is an infectious agent.

Devices used for the purpose of personal protection are intended to protect the wearer from breathing in respiratory hazards (e.g., wildfire smoke and other types of air pollution, mold, airborne respiratory viruses).

Device types

The term mask is widely used to describe any type of covering on the face, but the devices available on the market were designed for different purposes and can vary a lot in terms of the level of protection they can provide.


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These devices are designed to protect the wearer from breathing in respiratory hazards. Several different types of respirators are available on the market. Respirators designed for particulate hazards, such as N95 filtering facepiece respirators, commonly known as N95s, use specialized materials to filter out harmful particles and most are designed to fit tightly to the face to reduce leaks along the edges of the device. Other kinds of respirators are designed to protect the wearer from gases and vapors. The type of hazard determines the type of respirator that is appropriate.

elastomeric mask iconElastomeric facepiece and powered-air purifying respirators (PAPRs) are other types of respirators, which have been effectively used in workplace settings for decades, and can be cleaned and reused over long periods of time.

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Because they are rigorously tested to accepted standards, NIOSH-approved respirators can provide a higher level of confidence in the personal protection provided from respiratory hazards relative to other devices available and will be visually marked with a NIOSH approval label.


These devices, such as surgical or medical masks, do not fit tightly to the face but may be made of specialized materials to enhance filtration when breathing in or out. Surgical masks, which must meet Food and Drug Administration (FDA) performance requirements, are often worn to reduce the spread of infectious agents found in large droplets such as from saliva, sneezes, and coughs.

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Barrier face coverings

These devices cover the nose and mouth and may look like cloth face coverings or disposable masks, but are designed to meet an established standard for performance (ASTM F3502-21). As a result, barrier face coverings are expected to have an improved fit to the face and to provide some degree of particulate filtration, although their main function is to provide source control. Devices that meet the barrier face covering performance standard indicate this visually on their packaging.

Face coverings

These devices cover the nose and mouth and do not meet specific performance requirements, despite looking similar to barrier face coverings. These devices are typically made from single or multiple layers of cloth or filtering materials and often have gaps around the edges of the covering and the face. For many types of ambient air pollution, including wildfire smoke, face coverings often have low filtration efficiency in addition to poor fit and therefore offer little to no protection for the wearer.

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Dust masks

Also known as nuisance masks, these often look like respirators but are not required to meet specific performance requirements for fit and filtration. Importantly, dust masks do not provide protection against toxic particles.

Special considerations for some people

Some people have special considerations that may affect their ability to use respiratory protection. Most people can wear a respirator safely but for some it may be advisable to speak with their care provider before using one.

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Because they are typically designed for use by working-age adults, certain devices like NIOSH-approved respirators may not fit the faces of young children, reducing the protection provided.

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Individuals who are pregnant
Current research suggests that healthy, pregnant individuals can safely wear respiratory protection, but more research is needed.

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Individuals with certain health conditions
Some serious health conditions, including obstructive lung diseases such as COPD or severe asthma and cardiovascular diseases such as congestive heart failure or ischemic heart disease, may affect a person’s ability to safely tolerate prolonged respirator use.

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Individuals who may have trouble putting on a device correctly
Some individuals may not be able to properly put on their own device, but may be able to be assisted with properly putting on and wearing a device.

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