by Arthur T. Bradley, Ph.D.
A surgeon recently wrote to ask whether a modern pacemaker would survive an EMP. It would have been easy to provide a gut reaction and say, “No way!” After all, an EMP might generate fields on the order of 50 kV/m. But is that answer correct?
The surgeon went so far as to ask the pacemaker manufacturer (Medtronic) if they thought the device would survive. The company didn’t have an answer, but they did provide a set of known conditions that the pacemaker would survive (see Table 1). That information proved crucial to dialing in on what I hope is an educated answer.
Table 1: Medtronic provided max power levels vs distance
|Field Strength (watts)||Distance Required (feet)|
From literature (IEC E1 HEMP Signal), we can assume that a 50 kV/m E1 pulse would generate a total energy of about 0.1 Joules per square meter. Converting that to watts requires assuming both a pulse width and an area. For this back of the napkin calculation, let’s assume a pulse width of 5 nanoseconds and that the pacemaker, including wires, measures 0.1 square meters. Neither are exactly right, but they’re close enough for this first-order estimate.
Converting the energy to watts is done by:
The Medtronic table obviously doesn’t go this high, but we can assume that power rolls off based on the inverse square law (i.e., 1/d2). In other words, for every doubling of distance, the power drops by 4. Therefore, if we assume that the pacemaker will survive 2,000 watts at a distance of 30 feet (per the Medtronic table), we can extrapolate safe ranges for higher power levels, as shown in Table 2.
Table 2: Extrapolated max power levels versus distance
|Power (watts)||Distance (feet)|
This would suggest that Medtronic’s pacemaker could survive (without resetting) an EMP detonation that occurred at a distance greater than 960 feet. For simplicity, let’s round up and say that it would survive if the detonation occurred at >1/4 mile.
Given that a nuclear EMP will be most effective if it is detonated at least 25 miles in the atmosphere (above the Source Region) and will likely be at altitudes 10 times that height for greater coverage, it suggests that Medtronic’s pacemaker would easily remain operational.
The disclaimer, of course, is that all these calculations are back of the napkin. There are numerous sources of possible error, including the frequency content that Medtronic assumed when creating their table, the non-ideal roll off of power versus distance, the energy density of the E1 pulse, etc.
With all that said, the safe distances calculated are so much smaller than the actual detonation height (i.e., 1/4 mile vs 250 miles), I think it’s certainly reasonable to argue that such non-idealities won’t change the final conclusion.
In short, these calculations suggest that modern pacemakers, assuming that they perform similar to Medtronic’s, would have a very high likelihood of surviving a high-altitude nuclear EMP.
If you’re interested in learning more about EMPs and solar storms, kindly check out my book, “Disaster Preparedness for EMP Attacks and Solar Storms.” Exhaustive family preparedness information can also be found in my “Handbook to Practical Disaster Preparedness for the Family.” Finally, if you’re looking for an exciting post-apocalyptic saga, check out “The Survivalist (Frontier Justice)”.