Airport Scanners: Are They Safe Or A Health Risk?

Airport scanners are designed to improve security and enhance the customer travel experience. However, some travellers are concerned about the safety of the new 3D CT scanners, particularly regarding radiation exposure. While the TSA maintains that the scanners are safe, some travellers are sceptical due to a lack of publicly available information on the machines' radiation emission. The new scanners use significantly more energy than their predecessors, raising questions about the potential health risks for both travellers and employees who work with the machines.

How do airport scanners work?

Airport scanners use X-rays to build a picture of what's inside your bags. As your bag passes through the scanner, it crosses the path of X-rays, which can penetrate many materials due to their high energy. The X-rays pass through a detector, a filter, and then another detector. The first detector records the energy and position of the X-rays, while the filter blocks out the lower-energy X-rays, allowing only high-energy X-rays to pass through to the second detector.

By comparing the outputs of the two detectors, the machine constructs an image that shows the position of objects, what they're made of, and their density. Different materials are represented by different colours on the display monitor. Organic materials like paper, food, and explosives are shown in orange, while blue or green is used for metals and glass. The denser the material, the darker the colour.

The new 3D CT scanners produce a 3D density map of the bag, allowing TSA officers to manipulate the image on-screen and get a better view of the contents, reducing the number of bag checks.

What are the health risks of airport scanners?

The health risks of airport scanners depend on the type of scanner being used. Airport scanners can be categorised into two types: ionizing radiation scanners and non-ionizing radiation scanners.

Ionizing Radiation Scanners

Ionizing radiation scanners include backscatter x-ray machines and cabinet x-ray machines. These scanners emit ionizing radiation, which has enough energy to knock electrons out of atoms. This type of radiation is used to scan both passengers and luggage. While the use of x-ray backscatter machines for scanning passengers was discontinued in 2013 due to public concerns about ionizing radiation, these machines are still used for scanning luggage and carry-on items.

The health risk associated with ionizing radiation is the potential for it to cause tissue heating and thermal injury, particularly to the cornea of the eye, which is poorly perfused with blood and therefore less able to dissipate heat. However, the amount of radiation received from a backscatter machine is very low and comparable to the dose received from cosmic rays during a few minutes of flight. Additionally, safety measures are in place to limit the exposure of workers and travellers to high levels of ionizing radiation. These measures include the use of thick walls, lead curtains, locks, warning lights, and labels on the machines.

Non-Ionizing Radiation Scanners

Non-ionizing radiation scanners include metal detectors, millimeter-wave machines, and computed tomography (CT) scanners. These scanners emit non-ionizing radiation, which has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons from atoms.

Metal detectors use magnetic fields to identify metal objects, while millimeter-wave machines use radiofrequency waves to detect threats such as guns and knives. CT scanners, on the other hand, use X-rays to generate 3D images of the contents of carry-on bags, allowing for better threat detection.

The health risks associated with non-ionizing radiation are generally lower than those of ionizing radiation. Millimeter-wave scanners, for example, emit radiation with an intensity of 0.0001 W/m², which is less than the safety threshold of 10 W/m². This means that the risk of any health hazard from a millimeter-wave scan is extremely low.

Overall Health Risks of Airport Scanners

While there are potential health risks associated with airport scanners, the risk of exposure to harmful radiation is mitigated by safety measures and guidelines. The intensity of radiation used in airport scanners is generally very low, and the exposure time is brief, further reducing the potential for health effects. Additionally, passengers who are concerned about radiation exposure can opt for a pat-down search instead of walking through the scanners.

How does radiation exposure from airport scanners compare to other sources?

The radiation emitted by airport scanners is a cause of concern for many travellers. However, according to Dr. Lewis Nelson, a professor and chair of emergency medicine at Rutgers New Jersey Medical School, there is no need to worry about the amount of radiation airport scanners emit. Radiation is a general term for different kinds of moving electromagnetic energy: ionizing radiation (what X-ray machines emit) and nonionizing radiation (which includes radio and magnetic waves). Ionizing radiation has enough energy to knock electrons away from atoms, creating free radicals; these chemically reactive particles can damage DNA and increase the risk of cancer. However, ionizing radiation only has a real impact on our health when received in high doses, and the dose emitted by airport scanners is not high enough to cause harm.

The amount of radiation delivered by an airport scanner is tiny compared to other sources of radiation we encounter daily. For example, a chest X-ray exposes patients to roughly 1,000 times the radiation of an airport scanner. The Health Physics Society estimates that airport scanners deliver 0.1 microsieverts of radiation per scan, while a typical chest X-ray delivers 100 microsieverts of radiation. Furthermore, travellers are exposed to far more radiation during the flight itself than they are during the security screening process. Every minute on a plane delivers roughly the same dose of radiation as one airport scanner.

In addition, the American College of Radiology (ACR) has stated that a traveller would need to experience 100 backscatter scans per year to reach what the National Council on Radiation Protection and Measurement (NCRP) classifies as a Negligible Individual Dose. The ACR agrees with the NCRP's conclusion and states that a traveller would require more than 1,000 such scans in a year to reach the effective dose equal to one standard chest X-ray.

While the exact amount of radiation emitted by the new 3D CT baggage scanners has not been disclosed, it is worth noting that the energy levels of these new machines are significantly higher than their predecessors. Despite this, the operators of these machines, who are exposed to the radiation for prolonged periods, do not have any additional protective measures in place. This has raised concerns about the potential health risks associated with the new scanners, especially for pregnant women. However, according to one source, a technician for a similar CT scanner stated that the radiation emitted was "near undetectable" more than about a foot and a half away from the openings.

What safety measures are in place for airport scanners?

The safety measures in place for airport scanners include guidelines for using the equipment, which vary depending on the type of scanner.

Non-ionizing Radiation Scanning Equipment

Metal detectors use magnetic fields to identify metal objects. The magnetic field is created by a brief pulse of electrical current, which is reflected back to the machine if metal objects are present. This triggers a beeping noise to alert the TSA agent.

Metal detectors and millimeter wave machines use low-energy, non-ionizing radiation to scan surfaces. The energy that bounces back from the surface will show objects that are present, or it can generate an image for TSA agents to review. Millimeter wave machines are particularly important as they can show hidden threats such as guns and knives. If no threats are detected, the screen turns green and shows an “OK”. If a threat is detected, it will appear on the screen with a generic body outline to show the location.

Ionizing Radiation Scanning Equipment

Some screening equipment uses ionizing radiation, which has enough energy to knock electrons out of atoms. Airports use this type of radiation to scan passengers and luggage. Backscatter x-ray machines, for example, are used to detect threats such as weapons or explosives that a person could be carrying under their clothing. These machines use very low-energy x-rays that are reflected back to the machine itself. The amount of radiation received from a backscatter machine is comparable to the amount of cosmic radiation received during two minutes of flight, and the risk of health effects is very low.

In the case of cabinet x-ray systems, which are used to screen luggage and carry-on items, the machines have thick walls and lead curtains at entry and exit points to prevent radiation from escaping. They must also meet strict standards for radiation escape, and have locks, warning lights, and labels to ensure safety.

Additionally, the U.S. Food and Drug Administration (FDA) requires that all x-ray machines be correctly calibrated and maintained. The FDA's Center for Devices and Radiological Health (CDRH) ensures that all x-ray systems and other radiation-emitting equipment are built to use radiation safely.

How do airport scanners affect the speed of security checks?

The new airport scanners, such as the 3D CT baggage scanners, have been introduced to improve security and increase efficiency. These scanners use computed tomography (CT) X-ray technology to generate a 3D image of the contents of a carry-on bag, allowing TSA officers to manipulate the image on-screen and better view the bag's contents. This technology reduces the number of bag checks and allows travellers to leave everything in their carry-on bags, including electronics and food.

However, the new scanners have also been criticised for slowing down the security process. One reason for this is that the opening to the X-ray tunnel on a CT scanner is smaller than on traditional X-ray units, so travellers are advised not to force larger items into the tunnel. Additionally, travellers must place every carry-on item, including suitcases, into a bin for screening, which can be a confusing and time-consuming process. The new scanners also require travellers to wait for their bags at the end of the line, which can create bottlenecks and increase wait times.

Furthermore, there is a learning curve associated with the new technology. Both TSA agents and travellers need to adjust to the new process, which can initially slow down the security checks. However, over time, as people become more familiar with the new scanners, the security process is expected to speed up.

While the new scanners may affect the speed of security checks in the short term, the TSA maintains that the time spent going through security will be similar to that of traditional X-ray scanners. The time saved by not having to remove items from carry-on bags is expected to offset the additional time required for the CT scanner process.

Overall, while the new airport scanners may affect the speed of security checks in the short term, the technology is designed to improve efficiency and reduce wait times in the long run.

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