The superconducting magnet of NMR equipment produces strong magnetic and electromagnetic fields that can interfere with the function of cardiac pacemakers. Users of pacemakers and other implanted ferromagnetic medical devices are advised to consult with their physician, the pacemaker's manual and pacemaker manufacturer before entering facilities which house NMR equipment.
Precautions for work with NMR include the following:
1. Post clearly visible warning signs in areas with strong magnetic fields.
2. Measure stray fields with a gaussmeter, and restrict public access to areas of 5-gauss or higher.
3. The strong magnetic field can suddenly pull nearby unrestrained magnetic objects into the magnet with considerable force. Keep all tools, equipment and personal items containing ferromagnetic material (e.g., steel, iron) at least 2 metres away from the magnet.
4. Though not a safety issue, advise users that the magnetic field can erase magnetic media such as tapes and floppy disks, disable credit and automated teller machine (ATM) cards, and damage analog watches.
5. Avoid skin contact with cryogenic (liquid) helium and nitrogen; wear a protective face mask and loose-fitting thermal gloves during dewar servicing and when handling frozen samples.
6. Ensure that ventilation is sufficient to remove the helium or nitrogen gas exhausted by the instrument.
7. Avoid positioning your head over the helium and nitrogen exit tubes.
8. NMR tubes are thin-walled; handle them carefully and reserve them for NMR use only.
In the event of exposure to cryogen liquid or gas, the following first aid procedures are recommended:
- Immediately remove the victim from the cryogen hazard (or vice versa).
- Remove clothing that may interfere with the circulation of blood to the frozen tissues, but do so slowly, to prevent additional damage to skin.
- Do not rub or massage the affected region.
- Immerse the affected area in a warm water bath, < 40°C (< 105 °F) or exposure to warm air of the same temperature range.
- Eyes exposed to cryogen liquids or gases should be flushed them with warm water, < 40°C, for at least 15 minutes.
- The victim should seek immediate medical attention.