What the Nagasaki Hospital taught us about nuclear shelters

On the mornings of August 6th and 9th, 1945, the skies over Japan witnessed two enormous mushroom clouds rise over Hiroshima and Nagasaki, respectively.  Witnesses 60 kilometers away from the nuclear detonations felt only a slight tremor from this visual spectacle.  The story would be vastly different for those within 1 kilometer.  People outdoors were instantly vaporized, charred, or slammed against concrete buildings by a powerful shockwave traveling at approximately 1,500 kilometers per hour.  The smell of burning flesh, broken bones, and exposed organs were the hallmarks of ground zero in the Hiroshima and Nagasaki nuclear explosions.

The Hiroshima bomb (Little Boy) is estimated to have killed 140,000 people (40% of Hiroshima’s total population), while the Nagasaki bomb (Fat Man) killed an additional 73,000 (27% of Nagasaki’s population).  The Hiroshima bomb had a yield of 15 kilotons, and the Nagasaki bomb 21 kilotons.  The difference in mortality rates is thought to be due to the flatter topography of Hiroshima compared to the more irregular, mountainous terrain of Nagasaki.  This suggests that people living in mountainous cities might have a slightly higher chance of survival in a nuclear explosion than those in flat plains.

Despite this, the tragic story of Nagasaki reveals that the initial U.S. target (after Japan’s refusal to surrender following the Hiroshima detonation) was Kokura, a city 200 kilometers from Nagasaki, with a flatter topography and significant military industry.  However, poor weather conditions and low visibility over Kokura diverted the B-29 bomber “Bockscar” to Nagasaki, where the Fat Man bomb was ultimately dropped at 11:02 am on August 9, 1945.

It is estimated that virtually 100% of the people within a 500-meter radius of the detonation, and 90% within a 1,000-meter radius, died in Nagasaki during the first three months after the explosion.  However, the Nagasaki University Medical School Hospital, located just 600 meters from ground zero, remained standing thanks to its concrete walls and only 43% of the people inside, including medical staff and patients, perished.

The Nagasaki Hospital represents the first and only empirical evidence of how a sufficiently strong shelter can protect civilians from a nuclear explosion.  Although costly, this should be the first public or private preventative measure for such an event.

Globally, examples exist of how governments can prepare. Switzerland, a neutral country, is theoretically the best-prepared nation in the world to protect its citizens from a nuclear detonation, with a network of 360,000 bunkers capable of housing its nearly 9 million inhabitants.  Finland, another European country, has approximately 50,500 bunkers capable of sheltering 4.8 million people in the event of a nuclear attack, a matter of increased relevance given its recent NATO accession.

In the Middle East, the wars with Hamas and Hezbollah have forced Israel to invest hundreds of millions of dollars in bomb shelters for its civilian population.  Sderot, for example, is considered the world capital of bomb shelters, located just kilometers from the Gaza Strip and targeted by thousands of rockets from Hamas over the past two decades.

The escalation of conflict since October 7th of last year in the south with Hamas, in the north with Hezbollah, with the Houthis in Yemen, and with Iran since April of this year, has generated concern among the Israeli population.  Depending on their location, people have only 15 to 90 seconds to find a safe shelter upon hearing the air raid sirens.  Therefore, Israel has urged its citizens to build safe shelters in their homes if they do not have quick access to public shelters built by the state. In contrast, considering all the infrastructure destroyed in Gaza today, the Palestinian population (especially those living in Gaza) would be the most unprotected in the event of a nuclear attack on Israeli territory.

Similar actions should not be limited to Israel. Other Middle Eastern or global countries that might be involved in a future nuclear war should invest in sufficiently resistant and equipped shelters so that the maximum number of civilians can survive at least two weeks with adequate water, food, and sanitation conditions after a nuclear attack. Governments should also incentivize investment in private bunkers as does the State of Israel.

The people of Nagasaki had no time to seek even a decent shelter.  However, the Nagasaki University Medical School Hospital and its reinforced concrete walls showed us the way to survive the blast wave, thermal pulse, ionizing radiation, electromagnetic pulse, and radioactive fallout of a nuclear explosion.