Are Airport Scanners Dangerous? | The Expert Take

Airport scanners, including millimeter wave and backscatter units, are generally considered safe, operating within strict regulatory limits for radiation exposure.

Navigating airport security can sometimes feel like a gauntlet, a necessary step before the thrill of a new destination. Among the many questions that arise, the safety of those full-body scanners often surfaces, sparking curiosity and sometimes concern. Let’s break down what these machines are and what the science says about their impact on your health.

Navigating Airport Security: A Look at Scanner Technology

When you step into an airport security line, you typically encounter one of two primary types of advanced imaging technology (AIT) scanners. Both are designed to detect non-metallic and metallic objects concealed on a person’s body, enhancing security without physical contact. Understanding the distinction between these technologies is key to addressing safety concerns.

Millimeter Wave Scanners

The most common type of scanner used in airports today is the millimeter wave scanner. These units use non-ionizing electromagnetic waves, similar to those found in cell phones or Wi-Fi signals, but at a much lower power. The waves reflect off the body, and computer software creates a generic outline image to highlight any anomalies. The energy from these waves penetrates only the outermost layers of skin, dissipating quickly without entering internal tissues.

Backscatter Scanners (Historical Context)

A second type, backscatter scanners, utilizes very low-dose X-rays. These machines were designed to create a two-dimensional image of the body, revealing objects hidden under clothing. While they employed ionizing radiation, the dose was exceptionally small, comparable to the amount of natural background radiation received during a few minutes of flying at cruising altitude. It is important to note that the TSA has largely replaced backscatter units with millimeter wave technology in major airports, primarily due to public preference and privacy considerations, not due to safety concerns that exceeded regulatory limits.

Millimeter Wave Scanners: Understanding the Science

Millimeter wave technology operates in the radiofrequency spectrum, specifically between 30 GHz and 300 GHz. This falls into the category of non-ionizing radiation, meaning it lacks sufficient energy to remove electrons from atoms or molecules. This distinction is fundamental to understanding its safety profile. Ionizing radiation, like X-rays or gamma rays, can cause cellular damage by altering DNA, a risk not associated with non-ionizing radiation at the power levels used in these scanners.

The exposure from a millimeter wave scanner is extremely brief, lasting only a few seconds. The power output is minimal, well below established international and national safety limits for radiofrequency exposure. Regulatory bodies, including the FDA, continuously monitor and evaluate these devices to ensure they adhere to strict safety standards, ensuring public health is protected. The energy is reflected off the skin surface, not absorbed deeply into the body.

Backscatter Scanners: Past Use and Radiation Facts

Although largely phased out for primary screening, understanding the specifics of backscatter technology helps address lingering concerns. These scanners emitted a very low dose of X-ray radiation. The dose from a single scan was approximately 0.005 to 0.01 millisieverts (mSv), which is a tiny fraction of the average annual background radiation exposure most individuals receive naturally, which is around 3.1 mSv. To put this in perspective, a typical dental X-ray can expose a person to 0.01 mSv, and a cross-country flight can result in an exposure of 0.035 mSv.

The X-rays used in backscatter units were of very low energy, designed to penetrate clothing but not deeply into body tissues. The primary concern with ionizing radiation is cumulative exposure over time, but the dose from these scanners was so low that even frequent travelers would accumulate negligible amounts. The decision to remove them was largely driven by public perception and a preference for technology that does not use X-rays, regardless of the minimal dose.

Putting Radiation Exposure into Perspective

When considering any source of radiation, context is essential. The radiation exposure from airport scanners is often compared to everyday activities or other medical procedures to provide a clearer picture of the risk. A single airport scan, particularly with millimeter wave technology, contributes an almost immeasurable amount to a person’s overall radiation exposure. Even with backscatter scanners, the dose was equivalent to only a few minutes of natural background radiation exposure.

Travelers receive more radiation exposure from cosmic rays during a high-altitude flight than from passing through an airport scanner. For example, a six-hour flight from New York to Los Angeles exposes passengers to about 0.035 mSv of cosmic radiation, significantly more than any airport scanner. This perspective helps illustrate that the radiation dose from airport security equipment is well within safe limits and represents a minor contribution to overall exposure.

Comparison of Airport Scanner Technologies

Feature	Millimeter Wave Scanners	Backscatter Scanners
Radiation Type	Non-ionizing (Radiofrequency)	Ionizing (Low-dose X-ray)
Mechanism	Reflected waves create outline	X-rays penetrate clothing, create image
Depth of Penetration	Surface of skin	Minimal, just through clothing
Current Use in US	Widespread	Largely phased out

Specific Considerations: Pregnancy, Implants, and Children

While airport scanners are generally considered safe for all individuals, some travelers have specific concerns. It is always wise to be informed about your options and make choices that suit your personal circumstances.

• Pregnancy: For pregnant individuals, both millimeter wave and backscatter scanners are deemed safe. Millimeter wave technology uses non-ionizing radiation that does not penetrate the body. Backscatter scanners, while using X-rays, delivered such a low dose that it was considered negligible even for a developing fetus. The FDA and other health organizations have consistently affirmed their safety for pregnant individuals.
• Children: Children, with their developing bodies, are often a concern for parents. The radiation exposure from airport scanners is considered safe for children. The minimal exposure from a millimeter wave scanner poses no known risk, and the historical low-dose X-ray exposure from backscatter units was also deemed safe.
• Medical Implants: Individuals with medical implants such as pacemakers, defibrillators, or cochlear implants can safely pass through airport scanners. Millimeter wave scanners do not interfere with these devices. Metal detectors, which operate on different principles, might cause an alarm but do not harm the implant. Always inform security officers about your medical implant before screening.

Your Choices at the Checkpoint: Opting for a Pat-Down

Travelers always have the option to decline advanced imaging technology screening and request an alternative screening method. This alternative is typically a pat-down. Understanding this right and the procedure involved can provide comfort and control during the security process.

1. Requesting a Pat-Down: If you prefer not to go through the scanner for any reason, simply inform the security officer before entering the device.
2. The Pat-Down Procedure: A pat-down is a physical search conducted by a security officer of the same gender. It involves a thorough inspection of the body, including sensitive areas, over clothing. You can request a private screening area for the pat-down, and you are allowed to have a companion or another security officer present as a witness during a private screening.
3. When to Choose a Pat-Down: Some travelers choose a pat-down due to personal preference, religious reasons, or specific medical conditions that make standing in the scanner difficult. It is a valid and available option for anyone.

Relative Radiation Exposures (Approximate)

Source of Exposure	Approximate Dose (mSv)	Notes
Airport Millimeter Wave Scan	~0	Non-ionizing radiation
Airport Backscatter Scan (historical)	0.005 – 0.01	Low-dose X-ray
Dental X-ray	0.01	Single intraoral X-ray
Cross-country Flight (6 hours)	0.035	Cosmic radiation at altitude
Average Annual Background Radiation	3.1	From natural sources (soil, air, food)

Ensuring Safety and Security in Air Travel

The primary goal of airport security screening is to ensure the safety of all travelers and the aviation system. The technologies employed, including advanced imaging scanners, are rigorously tested and regulated by various government agencies. These agencies set strict standards for radiation emissions and operational safety, ensuring that the equipment poses minimal risk to the public. Continuous research and development also contribute to refining these technologies, making them more efficient and user-friendly while maintaining the highest safety protocols.

The balance between robust security measures and traveler well-being is a constant focus for aviation authorities. By understanding the science behind these scanners and knowing your options at the checkpoint, you can approach airport security with confidence, focusing on the excitement of your upcoming travels.