Airport Scanners: Can They See You Naked?

The use of full-body scanners in airports has raised concerns about privacy and human rights. While these scanners are intended to enhance security by detecting objects on or inside a person's body, they have been criticised for producing images of virtual strip searches, which some argue violate basic human rights and amount to child pornography if the scanned individual is a minor. However, it is important to note that the images produced by these scanners vary depending on the technology used and may only display a cartoon-like representation or a generic outline of a person with indicators of potential threat areas.

In response to privacy concerns, some countries have implemented measures such as using separate rooms for operators, preventing operators from seeing the faces of those being scanned, and utilising no-nudity full-body scanner software. Additionally, individuals typically have the right to refuse the scan and opt for alternative screening methods, such as a traditional pat-down or enhanced hand search.

The scanners use millimetre wave or X-ray technology

The scanners used in airports employ millimetre wave or X-ray technology to detect objects concealed underneath clothing. All scanning systems must use millimetre wave imaging technology, which works in a similar way to X-rays but emits far less radiation—only slightly more than a mobile phone or Wi-Fi device.

Millimetre wave scanners use non-ionizing radiofrequency waves to detect threats. The machine bounces the waves off the body and back to the scanner. If no weapons or other potential threats are detected, the screen turns green and displays an "OK". If an object is found, it will appear on the screen with a generic body outline to show its location.

X-ray machines, on the other hand, use ionizing radiation to scan passengers and luggage. Backscatter X-ray machines, in particular, use very low-energy X-rays that are reflected back to the machine itself. The amount of radiation received from a backscatter machine is said to equal the amount of cosmic radiation received during two minutes of flight, and the risk of health effects is extremely low.

Millimetre wave scanners come in two varieties: active and passive. Active scanners direct millimetre wave energy at the subject and then interpret the reflected energy. Passive systems, on the other hand, create images using only ambient radiation and radiation emitted from the human body or objects. In active scanners, the millimetre wave is transmitted from two antennas simultaneously as they rotate around the body. The reflected wave energy is then used to construct a three-dimensional image, which is displayed on a remote monitor for analysis.

Scanners can detect non-metal objects

Full-body scanners are devices that detect objects on or inside a person's body for security screening purposes, without physically removing clothes or making physical contact. Unlike metal detectors, full-body scanners can detect non-metal objects, which became an increasing 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 to create a 3D image of the body. They can detect metal objects on a person's body as the waves are reflected by metal, creating an image of the object's outline.
• X-ray-based scanners: These use low-dose radiation to detect suspicious metallic and non-metallic objects hidden under clothing or in shoes and body cavities.
• Infra-red thermal conductivity scanners: These use slight temperature differences on the surface of clothing to detect foreign objects.

Millimeter-wave scanners are the most commonly used technology for scanning passengers. They use non-ionizing electromagnetic waves to create a 3D image of the body. These waves can penetrate clothing but are reflected by the skin and any concealed objects, including metal. This means that while the scanners can detect metal objects, they cannot see through them. Instead, metal objects will appear as dark areas on the scan, prompting further inspection by security personnel.

X-ray scanners are typically used for scanning luggage. They create images of the contents inside bags by using low-level X-rays that pass through materials at different rates depending on their density. Metal objects, due to their high density, appear clearly on the scanner screen and are often highlighted in a distinct color. Like millimeter-wave scanners, X-ray scanners cannot see through dense metal objects.

While the original full-body scanners displayed images of naked bodies, current technology is less intrusive. Scanners now use generic human outlines instead of detailed body images to address privacy concerns. Passengers are usually given the option to refuse the scan and opt for a traditional pat-down instead.

Scanners can detect items inside the body

Full-body scanners 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 growing concern after various airliner bombing attempts in the 2000s.

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

• Millimeter wave scanners use non-ionizing electromagnetic radiation similar to that used by wireless data transmitters. The health risks posed by these machines are still being studied, and the evidence is mixed.
• X-ray-based scanners use low-dose radiation to detect suspicious metallic and non-metallic objects hidden under clothing or in the body's cavities. The dosage of radiation received is usually between 0.05 and 0.1 μSv, and the debate about the safety of this method has led multiple countries to ban their usage.
• Infra-red thermal conductivity scanners use slight temperature differences on the surface of clothing to detect foreign objects. Warm air is used to heat up the clothing surface, and the rate at which the clothing cools depends on what is beneath it. Items that cool the clothing at a different rate to the skin surface will be identified by a thermal image.

Millimeter wave scanners and X-ray-based scanners can detect items inside the body. Infra-red thermal conductivity scanners cannot detect items inside the body.

Millimeter wave scanners do not generate ionizing radiation and are considered safe for pregnant women, children, and those with medical implants such as pacemakers. However, the health risks of these machines are still being studied, and the evidence is mixed.

X-ray-based scanners, on the other hand, have been the subject of considerable debate regarding their safety. The dosage of radiation received is typically very low, but multiple countries have banned their usage due to safety concerns.

In the United States, the TSA exclusively uses Millimeter Wave AIT scanners, which show a generic outline of a person and do not reveal any identifying characteristics. These scanners replaced the previously used X-ray-based scanners in 2013 due to privacy and health concerns.

While full-body scanners can detect items inside the body, they cannot see anything inside, including tampons or other items. They rely on electromagnetic waves or X-rays to detect threats, and these cannot penetrate the skin.

Scanners can show a generic image of a human

The generic image is used by millimetre-wave scanners, which use non-ionizing electromagnetic radiation. These scanners are becoming more common due to privacy concerns. The millimetre wave scanners do not generate ionizing radiation and are considered safer.

The alternative X-ray scanners use very low energy X-rays to reflect off objects within the body and create an image. The X-rays reflect off anything denser than skin, such as metal. This is why passengers are asked to remove all metal items before entering the scanner.

The X-ray scanners are more detailed and comprehensive, and can detect items inside the body, such as drugs in the stomach. However, they are more controversial due to the detailed images they produce.

Scanners are not mandatory

In the US, passengers can decline full-body scanning in favour of physical screening, but in some cases, passengers may be required to undergo scanning if they have been selected for enhanced screening.

In Canada, passengers selected for a secondary search can choose between a full-body scan or a physical search.

In the UK, the Equality and Human Rights Commission has argued that full-body scanners may be a risk to human rights and could be breaking the law. As such, passengers can refuse this scan and opt for a traditional pat-down instead.

In Australia, a no-opt-out policy is enforced in relation to screening at airports. However, individuals with medical or physical conditions that prevent them from undergoing a body scan will be offered alternative screening methods.

It is important to note that the decision to undergo a full-body scan or an alternative screening method may vary depending on the country and specific airport policies. Passengers who refuse a scan may face different consequences, such as being banned from flying or undergoing an invasive pat-down.

Frequently asked questions