I am going to visit great apes in the wild (chimpanzees, orangutans or gorillas). Should I wear a face mask?

Yes, you should. IUCN’s experts recommend as a best practice that all visitors, including staff, tourists and researchers, who approach to a distance of 10 meters (33 feet) or less from wild great apes wear surgical a face mask (preferably a N95 respirator). You should always respect the distance regulations, however, it is highly possible that you might end up being closer than recommended at some point during the visit because the animal(s) moved closer and you are unable to move further away at that moment. So bring one with you for both yours and the animals’ health. They cost nothing, weigh nothing and save lives. Of course, if that happens then as soon as it is safe to do so move away: return to the proper distance.

Reducing Disease-Transmission with N95 Surgical Respirator Masks

Source: IUCN’s Best Practice Guidelines for Great Apes Tourism (Section 3.2.19).

Photo © Virunga National Park

The wearing of surgical facemasks by people coming into proximity with apes in research and tourism projects has been much debated since one of the biggest risks of human–ape disease transmission comes in the form of air-borne pathogens. Respiratory disease is the most prevalent cause of mortality in some ape populations. In 1999, IGCP’s assessment of the mountain gorilla tourism rules recommended increasing the minimum-viewing distance from 5 to 7 meters, on the basis of research on distances that respiratory droplets and aerosolized particles can travel. However, due to concerns about mask management and compliance, the decision to use masks was postponed, pending further evidence of the link between disease transmission and human presence.

When reviewing mask effectiveness, it is important to remember that much of the literature on facemasks assesses the protection of the wearer from infection, but in the case of tourism a potentially-infectious person is wearing the mask and our concern is to keep infectious particles in, not out. There are a number of pros and cons associated with the use of masks. Positive factors include that under ideal conditions masks are an effective barrier to exhaled pathogens. Although mask effectiveness lessens over time or in less than ideal conditions, the reduction in large particle aerosolization is still far more effective than wearing nothing. Arguments against the use of masks include the fact that apes must be habituated to visitors wearing them. Tourists also must be educated to ensure compliance, especially as any discomfort associated with the mask could reduce compliance. Under cooler situations, such as at high altitude, poorly fitting masks may cause fogging of glasses and interfere with photography and binocular use (*). The burden of ensuring mask supply is also a concern, as masks vary in effectiveness, and masks of appropriate quality are essential to the protective properties. Waste management is also an issue, as masks dropped in the forest would become fomites carrying concentrated potentially-infectious particles with significant disease risk.

A number of high-profile disease outbreaks in ape populations have been reported, as well as data showing that, in the right wind conditions, contaminated droplets can travel up to three times the recommended 7 meters minimum distance. Reports from multiple sites confirm that the rules established to protect apes from disease transmission are not enforced adequately or consistently and that safe distances are not maintained. Consequently, there is increasing advocacy for the use of facemasks by great ape researchers, tourists, and staff, in addition to other disease prevention measures. This practice is currently more common at research sites, especially those that have experienced fatal disease outbreaks in their study population (e.g., Taï National Park, Côte d’Ivoire); however, use of masks is also on the rise at tourist sites (e.g., chimpanzee tourism in Mahale Mountains National Park; mountain gorilla tourism in the DRC and Rwanda).

Masks vary in quality and efficiency. The main differences between a mask and a respirator are that masks fit relatively loosely and protect the wearer from large aerosol particle transmission whereas respirators have a sealing surface and fit tightly over the nose and mouth—they are designed to prevent both small and large particle aerosol transmission. N95 respirators are of better quality and have a better fit and seal than basic surgical masks, thereby providing improved prevention of aerosolized particle transmission. The better seal of an N95 mask may pro- vide some relief from fogging of camera lenses or binoculars, but conversely, the seal may reduce comfort and compliance if tourists feel it is more difficult to breathe. Facial hair is also a problem, as the seal is no longer ensured. Guidance on fitting and wearing of masks must be presented before approaching a group of apes, when the tourists will be rushing. Masks are only effective if they are worn properly.

We recommend that multi-layered, surgical-quality N95 (or higher5) respirators be worn whenever tourists or staff approach apes to a distance of 10 meters or less, that these must be properly used and disposed of, and that wearing a mask must not be considered justification for weakening other disease prevention rules. If N95 masks are not available, paper surgical masks may be used. N95 respirator masks cost approximately US$0.40 each plus the cost of shipping. This is small com- pared to the overall cost of great ape tourism operations, although the reliability of supply chains has to be assured. Issues of compliance and effectiveness will be critical in the management of masks as part of a disease prevention program. Compliance, comfort, tourist acceptance and mask disposal should all be monitored and the results used to inform and improve regulations and procedures (for more information on N95 respirators see next section).

Facemasks/Surgical Masks vs. N95 respirator masks

Source: IUCN’s Best Practice Guidelines for Great Apes Tourism (Appendix II).

Read: Poaching and Civil War Aren’t the Only Threats to Africa’s Dwindling Population of Mountain Gorillas (Photo © Elaisha Stokes)

It is recommended as best practice that all visitors, including staff, tourists and researchers, who approach to a distance of 10 meters or less from wild great apes wear surgical N95 respirators.

As there are a large variety of masks on the market, variously called ‘face masks’, ‘surgical masks’ or ‘respirators’, the following information describes the differences in mask types and provides additional information. All of this information is adapted from material produced by human health networks and/or adapted from recommendations from great ape veterinary experts.

Facemasks: A facemask is a loose-fitting, disposable device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. Facemasks may be labeled as surgical, laser, isolation, dental or medical procedure masks. Facemasks are made in different thicknesses and with different abilities to protect the wearer from contact with liquids. These properties may also affect how easily the wearer can breathe through the facemask and how well the facemask protects the wearer. If worn properly, a facemask is meant to help block large-particle droplets (greater than 50-100μm diameter), splashes, sprays or splatter that may contain infectious agents from reaching the wearer’s mouth and nose. Facemasks may also help reduce exposure of others to respiratory secretions of the wearer. While a facemask may be effective in blocking splashes and large-particle droplets, a facemask, by design, does not filter or block very small particles in the air that may be transmitted by coughs or sneezes. Facemasks also do not provide complete protection because of the loose fit between the surface of the facemask and the wearer’s face.

N95 Respirators: Although appearing similar to face masks to the layperson, an N95 respirator is a respiratory protective device designed to achieve a close facial fit and efficient filtration of airborne particles including very small airborne particles. The ‘N95’ designation means that in laboratory tests, the respirator blocks at least 95% of very small (less than 10 μm) particles, which include small particle aerosols generated directly from a cough or sneeze. Mask ratings above N95, i.e. N99 or N100, are also acceptable as they block a higher percentage of particles. An N95 respirator requires a proper fit, tight but comfortable, to the wearer’s face to be effective. A proper fit check is relatively simple: when inhaling, the respirator should collapse, and when exhaling there should be no leakage around the face. If properly fitted, the filtration capabilities of N95 respirators exceed those of face masks. However, even a properly fitted N95 respirator does not completely eliminate the risk of disease transmission. N95 respirators are not designed for children or people with facial hair because a proper fit cannot be achieved. As N95 respirators achieve a tighter facial fit, they may require more effort to breathe and this should be explained to the wearer before use. Some people with chronic respiratory, cardiac, or other medical conditions find it harder to wear N95 masks, but great ape tourism activities, especially those that require strenuous hiking, will probably not attract this sort of tourist. Some N95 models have exhalation valves that can make breathing out easier and help reduce heat build-up, although these will be more expensive. A type of N95 respirator called the Duck-Bill N95 respirator allows more room and has been tested by the MGVP (MGVP 2008) for comfort and reduced fogging of binoculars and glasses.

‘Surgical’ N95 Respirators: There are N95 respirators sold for use in construction or other dusty situations to protect the wearer from inhaling noxious particles. Surgical quality N95 respirators are approved for use in medical situations and meet additional performance standards for surgical face masks, and therefore it is the ‘Surgical N95 Respirator’ that is recommended as best practice for great ape tourism.

Mask Information Sources: More information on the types of masks and respirators described above can be found on a number of public health information websites.

Disposal of Used Masks and Respirators: Masks and respirators may only be used once. Used masks or respirators must be placed in a plastic bag and carried out of great ape habitat or back to a base camp and disposed of hygienically – as they are paper based, they can be burned. Staff members should wash hands or used a hand sanitizer after handling used masks.

Mask Procurement: Veterinary support networks and relevant public health ministries should be able to provide guidance on mask procurement options in each geographic region.

(*) 4 MGVP (2008) tested N95 ‘duck-bill’ shaped respirators, which provide more breathing room, and found that they are more comfortable, not as hot and do not cause eyeglasses to fog up as often.

[Reference] IUCN’s Best Practice Guidelines for Great Apes Tourism. If you are interested in the science literature on the topic, please check the original text that includes scientific references.

If you are planning a visit to any location where Great Apes live, please take the time to browse our Great Apes Rules and learn before you go. Thanks!


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