Airports And Luggage Search: A Coordinated Security Effort

Airport security is a complex process involving multiple stakeholders and stringent protocols. When it comes to luggage searches, various factors come into play, including the type of luggage (carry-on or checked), the contents of the luggage, and the technology used for screening. While most travellers are aware of restrictions on sharp objects, flammable liquids, and firearms, certain innocent items can also trigger a search. For example, dense organic matter like books or lip balm, clusters of wires, and even food items like peanut butter or salsa can arouse suspicion.

The Transportation Security Administration (TSA) in the United States employs advanced imaging technology and walk-through metal detectors to screen passengers and their luggage. These systems use non-ionizing radio-frequency energy to detect metallic and non-metallic threats without physical contact. Additionally, luggage undergoes X-ray screening to identify prohibited items and other threats.

The process of searching luggage varies across airports and countries. In some cases, security personnel may ask travellers to open their luggage and remove specific items, while in other instances, officers conduct the search themselves. It is important to note that checked bags are less likely to be searched for drugs but may be screened for other reasons, such as flammable materials or suspicious shapes.

Airport scanners can detect metallic and non-metallic objects

Airport scanners use different technologies to screen passengers and luggage. The two primary types of scanners are X-ray scanners and millimetre-wave scanners.

X-ray scanners are typically used for scanning luggage. They use low-level X-rays to create images of the contents inside bags. The X-rays pass through materials at different rates depending on their density. Metal, being dense, appears clearly on the scanner screen, often highlighted in a distinct colour such as blue or orange. However, X-ray scanners cannot see through dense metal objects. Instead, metal objects appear as opaque or dark areas on the X-ray image, prompting further inspection by security personnel.

Millimetre-wave scanners, on the other hand, are used for scanning passengers. They use non-ionising electromagnetic waves to create a 3D image of the body. These waves penetrate clothing but are reflected by the skin and any concealed objects, including metal. While these scanners cannot see through metal, they can detect metal objects on a person's body by creating an image of the object's outline.

In addition to detecting metallic objects, airport scanners can also identify non-metallic and organic materials. They can determine the density and mass of objects in luggage and mark organic materials such as drugs, food, explosives, or paper with an orange colour. Even if drugs are hidden inside a person's body, passengers suspected of swallowing drugs can be scanned with a full-body X-ray machine that can detect packages in the stomach. Airport scanners can also detect pills, regardless of whether they are in plastic, metallic, or non-metallic bottles.

Money is another item that can be detected by airport scanners, even the smallest amounts of metal or paper currency can be identified. Additionally, scanners can detect anything that is not part of the human anatomy and can spot concealed items under clothing.

While airport scanners are highly effective, they have some limitations. For example, everyday items like belt buckles, jewellery, and coins can trigger false positives, causing potential delays in the screening process. To address privacy concerns, modern scanners use generic human outlines instead of detailed body images. Technological advancements aim to continuously improve scanner technology, making security checks faster and more accurate.

Scanners can identify organic and inorganic materials

Organic materials are substances that contain carbon and hydrogen atoms. These materials can be further classified into different groups based on the presence of other atoms. For example, CHO-containing substances are those that have carbon, hydrogen, and oxygen atoms. CHON substances contain carbon, hydrogen, oxygen, and nitrogen atoms.

Inorganic materials, on the other hand, are substances that do not contain carbon-hydrogen bonds. These materials often consist of alkali and alkaline earth metals, as well as heavy metals such as iron, copper, manganese, zinc, titanium, lead, chromium, nickel, arsenic, tin, cadmium, silver, and cerium.

Scanners can differentiate between organic and inorganic materials by utilizing high-resolution mass spectrometry. This technique identifies substances based on their mass-to-charge ratio, which is unique for each compound. By measuring this ratio, scanners can determine the molecular formula of a substance, which in turn reveals whether it is organic or inorganic.

Additionally, scanners can also identify the double-bond equivalents (DBEs) of organic molecules. DBEs provide information about the unsaturation of compounds, which can help assess the ageing behaviour of particles. For example, oxidized compounds or aromatics can be grouped based on their DBEs.

The ability to distinguish between organic and inorganic materials is particularly useful in airport security. Scanners can detect prohibited items, such as flammable liquids, firearms, and sharp objects, as well as innocent items that may appear hazardous, like dense organic matter or stacks of books. This technology helps ensure the safety of passengers and facilitates a smoother travel experience.

Scanners can't detect items inside the human body

Scanners cannot detect items inside the human body.

Full-body scanners use a technology called Advanced Imaging Technology (AIT) for full-body scans at airport checkpoints. It is a millimeter-wave scanner that detects a wide range of metallic and non-metallic threats in a matter of seconds. The waves go through clothing and reflect off the passenger's skin and whatever else is concealed, bouncing back an image that is interpreted by the machine.

However, these scanners cannot detect items inside a person's body. They are designed to detect "metallic and non-metallic threat items", according to the TSA. This includes weapons made out of materials other than metal, like ceramics, and explosive materials and weapons that are not made of metal.

The TSA has also confirmed that "millimeter-wave imaging technology does not detect items inside a passenger's body or penetrate the skin".

Scanners can't detect items inside the human body, unless they're metal

Scanners used at airports are called full-body scanners. They are devices that detect objects on or inside a person's body for security screening purposes, without physically removing clothes or making physical contact. They can detect non-metal objects, which became a concern after various airliner bombing attempts in the 2000s.

There are three distinct technologies used in full-body scanners:

• Millimeter wave scanners: These use non-ionizing electromagnetic radiation similar to that used by wireless data transmitters. They do not generate ionizing radiation, but the health risks posed by these machines are still being studied.
• X-ray-based scanners:

• Backscatter X-ray scanners: These use low-dose radiation to detect suspicious metallic and non-metallic objects hidden under clothing, shoes, and in body cavities. The dosage received is usually between 0.05 and 0.1 μSv.
• Transmission X-ray scanners: These use higher-dose penetrating radiation to detect objects hidden under clothing and inside the human body. The dosage received is usually not higher than 0.25 μSv.

Infra-red thermal conductivity scanners: These do not use electromagnetic radiation to penetrate the body or clothing. Instead, they use slight temperature differences on the surface of clothing to detect foreign objects.

Full-body scanners cannot detect items inside the human body, unless they are metal. This is because the scanners use electromagnetic waves or X-rays to create an image of the person's body, and these waves/rays do not penetrate the skin.

While full-body scanners are effective at detecting weapons and other prohibited items, they have been criticised for being invasive and raising privacy concerns. In some cases, they have also been found to be ineffective, as they can be bypassed by terrorists or people trying to smuggle prohibited items. Additionally, the machines can malfunction and may not always be reliable.

Scanners can detect dense objects

Scanners used in airports can detect dense objects. Dense materials such as metals and liquids are typically the easiest for scanners to detect. However, certain materials that are low in density or have a complex composition can pose challenges for these scanners.

Dense objects can be detected using various technologies, including optical, acoustic, laser scanning, radar, thermal, and seismic methods. Time-of-flight 3D laser scanners, for example, use laser light to probe the subject and calculate the distance of a surface by timing the round-trip time of a light pulse. Structured-light 3D scanners project a pattern of light onto the subject and analyse the deformation of the pattern to determine the distance of each point in the field of view.

Dense objects that are challenging for scanners include organic materials, such as clothing, fabrics, and food products, especially if they are not tightly packed or contain multiple layers. Powders and granular substances, like fine sugar or salt, can also be difficult for scanners to distinguish accurately. Plastic and rubber items, such as containers or electronic devices, may appear opaque to scanners due to their ability to absorb X-rays.

Ceramic objects and liquid containers can also be challenging for scanners. Ceramics can appear as a solid mass, hindering the scanner's ability to accurately identify the contents. Dense liquid containers, such as opaque bottles or metallic flasks, can obstruct the scanner's view.

To improve the detection of dense objects, airports can employ advanced technologies, such as using multiple scanners or combining different scanning techniques. Additionally, ensuring that items are neatly and tightly packed can minimise the chances of additional inspection and facilitate a smoother security screening process.

Frequently asked questions