Updated October 2026: This post has been expanded from its original October 2018 version with a clearer explanation of why helium stopped iPhones, corrected figures for the gas involved, what tests showed afterward, and practical advice for anyone working near liquid helium. It is a historical account; details describe the time it covers, not today.
In October 2018, staff at Morris Hospital, southwest of Chicago, ran into a problem nobody expected. While a new MRI machine was being installed, phones and watches across the building stopped working. Around 40 devices were affected, and every one of them was an Apple product. Android phones in the same rooms carried on as normal.
The culprit turned out to be helium, the gas used to cool MRI magnets. The episode, first described by a member of the hospital's IT staff on Reddit and then investigated by the repair site iFixit, revealed an unusual weakness in a tiny component inside modern iPhones. This post explains what happened, the physics behind it, and what it means for people who work around helium.
What happened at Morris Hospital
MRI scanners use superconducting magnets that must be kept extremely cold. They are cooled with liquid helium, which boils at about 4.2 kelvin, or roughly minus 269 degrees Celsius. During installation work on the new GE Healthcare scanner, the magnet was being ramped down and a leak occurred. Helium that should have been vented safely outside escaped into the building instead.
According to iFixit's account, about 120 liters of liquid helium were released over roughly five hours. The MRI room shared its air supply with most of the facility, so the gas spread well beyond the scanner. Soon the IT team was taking calls about iPhones and Apple Watches that had frozen or would not turn on.
Correcting the numbers
The original version of this post repeated a figure stating that 120 liters of liquid helium equals about 90,000 cubic meters of gas. That overstates it by a factor of about a thousand. Liquid helium has a density of about 125 grams per liter, so 120 liters weighs roughly 15 kilograms. At room temperature and normal pressure, that much helium fills roughly 90 cubic meters, or about 90,000 liters. That is still enough gas to fill several rooms, but not an entire hospital several times over.
Why only Apple devices failed
Every computer, including a phone, needs a clock signal to keep its processor and other parts in step. For decades, most devices got that signal from a small quartz crystal oscillator. Apple had begun using a different kind of part: a MEMS oscillator, a microscopic resonating structure made of silicon. MEMS stands for microelectromechanical systems, the same family of technology used for motion sensors.
iFixit identified the part in the affected iPhones as a 32 kHz MEMS timing oscillator from the company SiTime. These parts sit inside a hermetically sealed package, but helium is unusual. Its atoms are so small that they can slowly pass through materials and seals that block other gases. Once helium gets inside the package, it changes the conditions around the vibrating silicon element, and the oscillator can stop working properly. When the clock stops, the phone effectively stops too.
According to iFixit, SiTime acknowledged that earlier generations of its parts could be affected by small-molecule gases such as helium. Android phones at the hospital likely relied on traditional quartz timing parts, which explains why they kept working.
Other phone sensors can be affected as well. The sensor maker InvenSense told iFixit that its gyroscopes and pressure sensors can be disrupted by helium but should recover once the gas is gone, and that accelerometers should see little impact.
Testing the theory
Two simple experiments backed up the explanation. The hospital IT staffer sealed an iPhone 8 Plus in a bag filled with helium. After about 8 minutes and 20 seconds, it locked up and its clock stopped. The iFixit writer tried the same thing with an iPhone 8, which shut off after about four minutes.
| Device or test | What happened |
|---|---|
| iPhone 6 and later at the hospital | Affected |
| Apple Watch (all models then on sale) | Affected |
| iPhone 5 in the same building | Not affected |
| Android phones in the same building | Not affected |
| iPhone 8 Plus sealed in a helium-filled bag | Locked up after about 8 minutes 20 seconds |
| iPhone 8 in a helium atmosphere (iFixit test) | Shut off after about 4 minutes |
Source: iFixit, "iPhones Are Allergic to Helium" (2018).
The iPhone 5 result is a useful clue. It came from the generation before the affected models, and it was the one Apple phone in the building that kept working.
What happened next
The story drew wide coverage because it seemed so strange, but the explanation was not entirely new. Apple's iPhone user guide already included a warning that exposure to high concentrations of industrial chemicals, including evaporating liquefied gases such as helium, could damage or impair the device. Its suggested fix, as summarized by iFixit, was to leave the device disconnected for about a week so the helium can diffuse out, and then charge it for up to an hour.
Recovery at the hospital was slow and not always complete. Most devices came back after the helium dissipated, but iFixit reported that one iPhone had severe cellular service problems afterward, and some Apple Watch touchscreens still did not work after several days.
The incident also highlighted a building-design issue. MRI suites are supposed to vent helium safely outside through a dedicated pipe, because a sudden release of the gas can displace oxygen in an enclosed room. The fact that an Apple Watch reacted before anyone noticed a problem with the air was a reminder of how much gas had escaped.
What this means for you
For almost everyone, this is a curiosity. Helium from a party balloon is not concentrated enough, or present long enough, to harm a phone. The people who should pay attention are those who work around large amounts of helium:
- Hospital and MRI staff, especially during installation, servicing or a magnet quench, when large volumes of helium boil off.
- Laboratory workers who handle liquid helium for cryogenics, physics experiments or instrument cooling.
- Industrial workers in welding, leak testing or gas supply, where helium is used in volume.
Practical steps:
- Keep phones and watches out of the room when a large helium transfer or vent is planned.
- If a device stops responding after exposure, do not keep trying to charge or restart it. Leave it switched off and disconnected in fresh air so the helium can diffuse out, as Apple's guidance suggests, then try charging again.
- Treat a helium leak as a safety issue first. If devices start failing near an MRI suite, it may mean gas is accumulating indoors. Report it to facilities or safety staff right away.
The bottom line
The Morris Hospital incident was a rare case where a design change invisible to users, swapping a quartz clock for a silicon MEMS one, produced a dramatic and very specific failure. The fix was patience, the cause was physics, and the lesson for facilities was to make sure helium goes where it is supposed to: outside.
Sources
Top image: "An MRI scanner" by Walter Davies, CC BY-SA 4.0, via Wikimedia Commons (resized). Charts by Thank You Robot.
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