Radioactivity in japan after being bombed

Health Effects: Are Hiroshima and Nagasaki Still Radioactive?

by Jay Speakman

On August 6, 1945, the city of Hiroshima experienced an unprecedented event when the United States dropped an atomic bomb on the city. The immediate explosion caused massive destruction and loss of life, with thousands perishing instantly and many more suffering from the aftereffects. 

Understanding the current levels of background radiation in the cities of Hiroshima and Nagasaki help us analyze the consequences of using these weapons. People often wonder if the city is still radioactive and how it affects residents and visitors today. To an extent, it is. 

In this article, we aim to provide a clear assessment of Hiroshima's present-day radiation levels, exploring the historical context, radioactive decay, cleanup efforts, and current scientific data. 

Table of Contents

  • 01

    Historical Significance of Hiroshima and Nagasaki

  • 02

    Radioactive Decay and Cleanup Efforts

  • 03

    Is Hiroshima Still Radioactive Currently?

  • 04

    PPE Use for Public and Environmental Safety

  • 05

    Safety Precautions and Regulations Implemented by Local Authorities

  • 06

    Recommendations for PPE and MIRA Safety Products

  • 07

    Lessons We Are Still Learning from Nuclear Bombs

  • 08


Historical Significance of Hiroshima and Nagasaki

The Hiroshima atomic bombing marked a tragic event in history. A B-29 bomber dropped the bomb from far above the ground, with its detonation obliterating more than half of the city. The nuclear warhead on the Hiroshima bomb (nicknamed Little Boy) exploded just a few feet above the ground, resulting in fallout that would last for years.

The immediate blast killed an estimated 70,000 people, with the death toll rising significantly due to radiation exposure and injuries. Everything within a one-kilometer radius died, and entire buildings were instantly vaporized. The radiation would plague those areas for years after.

Just after the bomb detonated, the radiation received immediately following the explosion rose to unprecedented levels. Survivors suffered from acute radiation sickness, which included symptoms like nausea, hair loss, and bleeding. Many succumbed to these effects in the weeks following the bombing. Residual radiation was emitted for miles around the city for years to come. Unfortunately, just a few days after, the same thing happened in Nagasaki on August 9th, 1945.

Long-term effects have been profound. Over the years, radiation in Hiroshima has given rise to increased cancer rates and genetic mutations among survivors. The environmental damage was also significant, with radiation affecting the soil, water, and local wildlife. These long-term effects underscore the legacy of the bombings and the importance of understanding and mitigating radiation's impact on human health and the environment.

Radioactive Decay and Cleanup Efforts


Scientist wearing protective uniform and glove

Source: Envato

Radioactive decay is a process where unstable atomic nuclei lose energy by emitting radiation. The bomb dropped on Hiroshima used uranium-235, which has a half-life of about 700 million years. This means it takes that long for half of the radioactive atoms to decay. However, the most harmful radiation from the bomb, such as gamma rays and neutrons, diminished rapidly within the first few weeks, returning to low levels fairly soon.

The bombings of Hiroshima and Nagasaki are still the largest bombs dropped on human civilization. Even though now there are extremely low levels of background radiation in those parts, it's hard to illustrate the damage immediately following the explosion, especially on the citizens of Hiroshima and Nagasaki in August 1945, who suffered from deformities and issues like impairment in physical growth for years after the bomb exploded.

Post-bombing, extensive cleanup, and decontamination efforts were vital. Initial efforts focused on removing debris and decontaminating areas with high radiation. Over time, more sophisticated techniques, including soil removal and treatment, were used to reduce radioactive contamination.

Scientific data from the years immediately following the bombing show that radiation levels decreased significantly. Further studies indicated that the residual radiation declined rapidly within the first few months. By the 1950s, these were back to natural radioactivity levels, allowing for the city’s reconstruction and the return of its residents.

Is Hiroshima Still Radioactive Currently?

Hiroshima, once the site of unprecedented nuclear devastation, now registers radiation levels comparable to any other place on Earth. Over the decades, radioactive decay has made the city safe for residents and visitors.

Scientific bodies like the Radiation Effects Research Foundation (RERF) continue to monitor these levels to ensure radiation in Hiroshima and Nagasaki remains stable. According to the RERF, while it takes several years to bring radiation levels on par with the extremely low levels present anywhere on earth, there's also the risk of radioactive particles escaping into the atmosphere or blown away by the wind into countries in other parts of the world.

Present-day Radiation Measurements in Hiroshima

Today, decades after the atomic bomb was dropped, radiation levels in Hiroshima are nearly indistinguishable from natural background radiation levels anywhere on earth. The initial radiation jump subsided quickly, and the explosion ensured that most of the radioactive material was dispersed in the atmosphere, significantly accelerating the decay process and reducing long-term contamination.

Radiation levels in Hiroshima nowadays are monitored using advanced scientific instruments. These measurements show low levels of background radiation on par with other places. For example, typical background radiation levels are around 0.1 microsieverts per hour, and the readings in Hiroshima today are consistent with this standard.

Comparison with Natural Background Radiation Levels

To understand the current radiation levels in the Japanese cities of Hiroshima and Nagasaki today, we must compare them with natural radiation levels. Natural background radiation comes from various sources, including cosmic radiation from space and naturally occurring radioactive materials in the Earth's crust, such as radon gas. On average, people are exposed to about 2.4 millisieverts of natural background radiation levels per year. 

Radiation measurements in Hiroshima today show levels that are comparable to this natural radiation. According to a report by the Radiation Effects Research Foundation, Hiroshima's residual radiation levels are now similar to those found in any other part of the world. This demonstrates that the radioactive materials from the bomb have decayed to levels that do not pose significant health risks.

Contribution of Scientific Organizations and Research Studies

Comparing substances hiroshima radioactive


Scientific organizations have been instrumental in monitoring and studying radiation levels in Hiroshima since the nuclear explosion. The Radiation Effects Research Foundation is a key player in this ongoing effort. Established as a binational organization between the United States and Japan, RERF has been conducting extensive studies on the health effects of atomic bomb radiation on survivors and the environment.

RERF and other research institutions have implemented advanced methods to measure radiation levels and study their impact on human health and the environment. These organizations use a variety of approaches, including dosimeters, devices that measure exposure to ionizing radiation. Their continuous monitoring quickly detects and addresses any changes in radiation levels.

Additionally, studies have examined genetic mutations, cancer rates, and other long-term health effects among survivors and their descendants, especially among those who were exposed to direct radiation within the blast radius. These studies help identify any long-term genetic impacts of radiation exposure and inform future safety standards.

For example, a study published by RERF examined the radiation dose absorbed by Hiroshima survivors and found that the levels of exposure were significantly lower than initially feared. This research has shaped radiation protection standards and influenced public health policies.

Radiation Monitoring and Public Health

Continuous radiation monitoring in Hiroshima helps ensure the safety and well-being of its residents and visitors. Scientific organizations conduct regular assessments and publish their findings to keep the public informed around issues such as radiation poisoning. These efforts are complemented by local and national government initiatives aimed at maintaining low radiation levels and addressing any potential health risks.

The findings from these studies provide reassurance that the current radiation levels in Hiroshima do not pose any serious health hazards. They also highlight the importance of ongoing monitoring and research in managing radiation exposure and protecting public health.

Technological Advancements and Safety Measures

Technological advancements have also improved radiation monitoring and safety measures in Hiroshima. Modern dosimeters and other radiation detection devices are more accurate and sensitive than those used in the past and can easily detect direct radiation within a one-kilometer radius or higher. These advancements let scientists detect even the slightest changes in radiation released respond promptly.

In addition, public education campaigns have been instrumental in raising awareness about radiation safety. These campaigns provide residents and visitors with information on how to protect themselves from potential radiation exposure and what steps to take in case of a radiation emergency.

Implications for Modern Nuclear Safety

Scientist wear protection suit checking chemical and water analysis


The Hiroshima experience offers valuable lessons for managing radiation safety today and for the future. The city's recovery and ongoing monitoring efforts demonstrate the importance of scientific research, technological advancements, and public awareness in addressing the challenges posed by radiation exposure.

Data and insights from Hiroshima have informed global radiation protection standards and emergency preparedness plans. For instance, the lessons learned from Hiroshima were applied to the response and recovery efforts following the Fukushima nuclear disaster in 2011. The continuous monitoring and research conducted in Hiroshima, thus, provide a model for managing radiation exposure and securing public safety in the event of future nuclear incidents.

PPE Use for Public and Environmental Safety

Man dressed in chemical protection suit


 Safeguarding the health and safety of residents and visitors in Hiroshima involves continuous monitoring and the implementation of safety precautions. Here's an in-depth look at how personal protective equipment (PPE) and other safety measures contribute to public and environmental safety in Hiroshima.

Impact on the Health of Current Residents

The health of Hiroshima's current residents is closely monitored to see that they are not exposed to harmful radiation levels. Following the rapid fall in radiation levels in the aftermath of the bombing, the citizens now have radiation exposure comparable to natural ambient levels observed around the world. However, maintaining these safety standards requires consistent vigilance and using appropriate protective measures.

PPE protects people who might come into contact with residual radioactive materials, particularly during construction or excavation activities where buried radioactive materials might be disturbed.

Evaluation of the Environment: Soil, Water, Flora, and Fauna

The environment in Hiroshima, including its soil, water, flora, and fauna, has undergone extensive evaluation to ensure that it is safe for the ecosystem and human habitation and the amount of residual radiation is low. Studies by RERF and continuous observation by local authorities have shown that radiation levels in the soil and water are now within safe limits to prevent damage to human bodies.

Regular environmental assessments include testing soil samples for residual radioactive materials and ensuring water sources remain uncontaminated. Flora and fauna are also monitored to detect any signs of radiation-induced mutations or health issues, which can serve as early indicators of environmental problems.

Safety Precautions and Regulations Implemented by Local Authorities

Local authorities in Hiroshima have implemented stringent safety precautions and regulations to protect public health and the environment. Standard PPE for such activities includes gloves, masks, and protective clothing designed to shield against particulate contamination and protect against acute radiation exposure.

Radiation Monitoring and Reporting

Continuous radiation monitoring is conducted in various parts of the city. Data from these monitoring activities are publicly available, ensuring transparency and keeping residents informed about radiation levels and the various types of radiation.

Building and Construction Regulations

Special regulations govern construction activities to prevent exposure to buried radioactive materials. Workers are required to use PPE, including gloves, masks, and protective suits, to minimize contact with contaminated materials.

Public Health Campaigns

Ongoing public health campaigns educate residents about radiation safety and the importance of using protective measures when necessary. These campaigns also inform the public what to do in case of any radiological incident.

That's because atomic bombs differ from conventional bombs. The initial radiation emitted is extremely high, and is often many hundreds times the radiation a person would receive otherwise. They even cause non-radioactive materials to become radioactive in just 24 hours after the bombing. 

Public health campaigns ensure that people understand how to react in the immediate aftermath, how to mitigate exposure to radiation a week later and even months after the bombing. Since the bomb were detonated, Japan and other countries have continued to spread awareness about the effects of radiation and take measures to ensure that history doesn't repeat itself.

Emergency Preparedness Drills

Regular drills and emergency preparedness exercises are conducted to ensure that both residents and authorities are ready to respond effectively to any radiological emergency. These drills often involve using PPE and other safety protocols.

Decontamination Protocols

If there is any residual radioactive contamination, strict decontamination protocols are followed. These include isolating the affected area, using specialized cleaning agents, and ensuring that decontamination personnel are equipped with appropriate PPE. 

Recommendations for PPE and MIRA Safety Products

To further implement safety measures, incorporating advanced PPE from reputable suppliers can be beneficial. For instance, MIRA Safety offers a range of products designed to protect against radiation exposure:

  1. Gloves: Protect against contact with contaminated surfaces. MIRA Safety's Hazmat Gloves offer high resistance to chemicals and radioactive particles for complete hand protection.

  2. Masks: Prevent radioactive dust inhalation. The MIRA Safety CM-6M Gas Mask paired with a P3 filter is ideal for filtering out particulate contamination.

  3. Protective Clothing: Shields the body from radioactive dust and particles. The MIRA Safety HAZ-SUIT is a durable, full-body suit designed to protect against chemical and radioactive hazards.

  4. Radiation Detection and Monitoring Equipment: Advanced radiation detectors and dosimeters help in accurately monitoring radiation levels, ensuring that both workers and residents are not exposed to harmful doses.

  5. Protective Gloves and Clothing: High-quality gloves and protective clothing provide the appropriate protection for workers handling potentially contaminated materials, providing an additional layer of safety.

Hiroshima's commitment to maintaining low radiation levels and protecting public safety through rigorous observation and the use of PPE has made the city safe for its residents, tourists, and visitors. Furthermore, leveraging advanced PPE solutions from MIRA Safety can further improve these efforts for continued protection against any potential radiation risks.

Lessons We Are Still Learning from Nuclear Bombs

Hiroshima’s recovery and restoration offer valuable lessons in resilience and the importance of decontamination efforts. The city’s transformation from devastation to safety teaches us how thorough cleanup and long-term monitoring can mitigate radiation risks.

These lessons emphasize the need for immediate, effective response strategies and a reliable infrastructure to manage long-term impact in modern nuclear accidents. Continuous emergency preparedness remains important, including readiness to protect public health and the environment in the event of future incidents.


Current findings confirm that Hiroshima’s radiation levels are now comparable to natural levels, assuring safety for the people living or visiting it. The city’s successful recovery and ongoing safety measures highlight the advancements in nuclear safety and the resilience of its community. 

Stay informed about nuclear safety and radiological health. Preparedness is key  —understand the importance of emergency protocols and consider investing in reliable protective equipment from trusted providers like MIRA Safety to ensure personal and public safety in any radiological event.