Airport Swabs: Security's Latest Weapon Explained

Airport security officers use small white swabs to conduct Explosives Trace Detection (ETD) tests on passengers' hands, luggage, and other items. These swabs are used to collect and analyse trace samples for particles of explosive materials. The test is highly sensitive and can detect extremely small traces of explosives, including nitrates and glycerin, which are found in some harmless everyday products, leading to false positives. While swabbing is sometimes done randomly, it can also be triggered by factors such as setting off a metal detector or previous positive test results. The procedure is minimally invasive and aims to ensure the safety of the aviation environment.

Swabs are used to detect explosives

Swabs are used at airports to detect explosives. This is done by checking passengers' hands, luggage, and other items for traces of explosive materials. The Transportation Security Administration (TSA) conducts these swab tests as part of its Explosives Trace Detection (ETD) programme. The tests are designed to be quick and minimally invasive, with officers using small pieces of damp paper or cloth to collect samples from passengers' hands or belongings. These samples are then analysed by ETD machinery, which can detect extremely small traces of explosives.

The purpose of swab tests is to ensure the safety of the aviation environment and protect against potential terrorist attacks. While the tests cannot detect all chemicals that might be used in explosives, they focus on two key compounds: nitrates and glycerin. These compounds are commonly found in everyday products, which can lead to false positives during the testing process. To minimise the chances of a false positive result, passengers are advised to pay attention to their personal hygiene and the chemicals they come into contact with before travelling.

In addition to detecting explosives, swab tests can also identify residues from firearms or ammunition. This includes particles from shooting activities such as clay pigeon shooting or handling spent casings. It is important for passengers who have engaged in such activities to be prepared to explain any positive test results and provide relevant documentation if necessary. While swab tests are primarily focused on explosives detection, they can also indirectly lead to the discovery of narcotics or other illicit substances during the security screening process.

The TSA recognises that certain professions and hobbies may increase the likelihood of triggering the ETD machine. For example, hunters, firefighters, and military or law enforcement personnel regularly come into contact with accelerants and munitions. As a result, the TSA advises passengers in these occupations or with related hobbies to be aware of the potential for positive test results and to cooperate with additional security measures if necessary. Overall, swab tests at airports play a crucial role in ensuring the safety and security of air travel by helping to identify potential threats and mitigate risks associated with explosives and other hazardous materials.

They can also detect firearms residue

Swab tests are commonly used at airports to detect traces of explosive materials and/or drugs. They are often used as an additional security measure when a passenger has triggered a metal detector or is deemed suspicious. These tests are highly sensitive and can detect even the smallest traces of certain compounds, such as nitrates and glycerin, which are used in making explosives.

While swab tests are primarily used to detect explosive materials, they can also detect firearms residue. This is known as gunshot residue (GSR) or cartridge discharge residue (CDR) and consists of particles expelled from the muzzle of a gun when a bullet is fired. GSR includes burnt and unburnt particles from the explosive primer, the propellant (gunpowder), stabilisers, and other additives. It may also contain metallic particles from the cartridge casing, bullet jacket, or dirt/residue from the barrel of the firearm.

GSR can be detected on the skin, hair, and clothing of individuals who have discharged a firearm or were in close proximity to a firearm when it was discharged. Airports may use swab tests to detect GSR on the hands of passengers, particularly the web of the non-firing hand, as this area is less likely to have come into direct contact with the firearm and therefore may provide a more accurate indication of GSR presence.

The swabs used at airports are typically small pieces of damp paper that absorb particles from the skin. These swabs are then placed in a machine that analyzes the sample for traces of explosives or other illicit substances. In the case of GSR detection, advanced technologies such as trapped ion mobility spectrometry coupled with mass spectrometry can be used to identify both inorganic and organic constituents of GSR.

It is important to note that false positives can occur with airport swab tests, as GSR may be present on individuals who have recently been in contact with firearms for recreational purposes, such as shooting ranges or clay-pigeon shooting. To avoid potential misunderstandings, individuals who have engaged in such activities may consider bringing a receipt or other proof of their participation to the airport.

Certain chemicals can cause false positives

Swab tests at the airport are used to check for chemicals that might be used as explosives. The test looks for two sets of compounds: nitrates and glycerin. However, these compounds are also found in some harmless everyday products, which can lead to false positives. For example, some hand creams and soaps contain glycerin, which can trigger a positive result. Similarly, traces of explosives can be found on the belongings of people who work with them frequently, such as miners.

It's important to note that the test is highly sensitive, which means that even small amounts of these chemicals can be detected. This sensitivity can lead to false positives, especially for individuals who have been in contact with certain chemicals or environments. For instance, individuals who engage in activities like shooting or handling ammunition may have residue on their hands or belongings that can trigger a positive result. Even handling emergency flares can cause a positive test result, as is often the case with offshore sailors.

To avoid potential false positives, it is recommended to pay close attention to hygiene and avoid certain chemicals before travelling. This includes thoroughly washing hands after using hand soaps containing glycerin and being cautious of the chemicals in your environment. Additionally, arriving at the airport early can help in case additional testing or evaluation of belongings is required.

While false positives can be inconvenient, the highly sensitive nature of the swab tests is crucial in ensuring the safety and security of air travel. These tests are an important tool in detecting potential threats and protecting passengers and crew. However, it is also important to acknowledge that the current testing methods may not be perfect, and further improvements can be made to increase accuracy and reduce the impact on travellers.

Airports use random swabbing as a security measure

The primary purpose of swabbing is to check for chemicals that might be used in explosives. Specifically, the tests look for two sets of compounds: nitrates and glycerin, which can be used to make various types of bombs. While the tests are highly sensitive, nitrates and glycerin are also found in some harmless everyday products, leading to false positives. For example, hand creams containing glycerin or handling fireworks at places like Disneyland can cause a positive test result.

Random swabbing is used to mitigate the potential for discriminatory checks and to ensure that a broad range of individuals are tested. This randomness also acts as a deterrent, as potential threats cannot predict or avoid the swabbing process. In addition, random swabbing helps to identify any issues that may have been overlooked during the initial security screening. By swabbing randomly selected passengers, security personnel can ensure that no one is intentionally or unintentionally targeted based on appearance or other factors.

While the swabbing process is generally random, certain factors may increase the likelihood of being selected. For example, individuals with prosthetic limbs or joint replacements may be more likely to be swabbed due to the presence of metal, which can trigger the detectors. Additionally, those with professions or hobbies that involve handling explosives, accelerants, or munitions may also be more likely to be selected for swabbing, as they may have trace residues on their persons or belongings.

Swabs are not testing passengers' DNA

Swabs are used at airports to ensure the safety of passengers and staff. The Transportation Security Administration (TSA) uses swab tests to check passengers' hands, luggage, and other items for traces of explosives. This is known as Explosives Trace Detection (ETD) testing, and it involves using a small piece of damp paper or cloth to collect a sample from the surface being tested. The swab is then placed in a machine that analyses the sample for extremely small traces of explosive materials.

It is important to note that these swab tests are not used to test passengers' DNA. The TSA has clarified that the swabs are specifically designed to detect explosive materials and are not calibrated to test for DNA, viruses, illnesses, or narcotics. While the tests can sometimes detect residues from firearms usage, such as shotgun shells, they are primarily focused on identifying explosive substances.

The purpose of swab testing is to enhance security and protect against potential terrorist attacks. Airports utilise these tests to detect and prevent the transportation of explosive devices or materials that could pose a threat to aviation safety. The tests are highly sensitive and can identify even minute traces of explosives. However, it's important to be aware that certain everyday products, such as hand soaps and creams containing glycerin, can trigger a false positive result.

Passengers who test positive for explosive residue may be subject to additional searches or screenings. It is recommended to cooperate with the TSA agents and provide any relevant information or explanations for the test results. While privacy advocates have raised concerns about the potential for discriminatory use of these tests, the TSA emphasises its awareness of professions and hobbies that may cause individuals to alarm the ETD machine. Hunters, firefighters, and military and law enforcement personnel, for example, may test positive due to their regular exposure to accelerants and munitions.

Frequently asked questions