Seventy years after the U.S. dropped two atomic bombs on Japan, the threat from nuclear weapons is steadily increasing, according to a scientist who is an expert on nuclear events.

Dr. Cham Dallas, a University of Georgia professor and radiation expert, detailed in the online academic news site The Conversation just how likely a nuclear attack is today, and what would happen in urban areas if an attack were to occur. According to Dallas, so few medical professionals have the appropriate training in how to treat those with nuclear blast injuries that’s unclear how medical facilities could cope, particularly in urban areas.

Today, the risk for a nuclear exchange – and its devastating impact on medicine and public health worldwide – has only escalated,” Dallas wrote. “Nuclear weapons are spreading to more nations, and international relations are increasingly volatile. The developing technological sophistication among terrorist groups and the growing global availability and distribution of radioactive materials are also especially worrying.”

“Models show that such an event in an urban area in particular will not only destroy the existing public health protections but will, most likely, make it extremely difficult to respond, recover and rehabilitate them,” Dallas said. “With medical facilities decimated after a detonation, treating the injured will be a tremendous challenge. We would need predicted casualty distributions and locations to figure out how to best allocate what resources and personnel remain.”

Dallas has studied the effects of nuclear events for more than 30 years and has been involved in humanitarian efforts, research and teaching. He’s traveled with multiple expeditions to Chernobyl and Fukushima and is currently helping with the proposal for a nuclear global health workforce. Dallas has given three different presentations to the United Nations on the effects from the Chernobyl nuclear accident in Ukraine and has also testified before the U.S. House and Senate Homeland Security Committees and the National Academy of Sciences on nuclear issues.

A nuclear blast would be catastrophic not just for people, but also on the environment and the nation’s economy as such large areas of territory would be destroyed, Dallas reported.

Decisions to evacuate at-risk populations must be made within hours, but plans for and criteria to evacuate are lacking. And the scale of these evacuations and potential resettlement is tremendous,” he wrote.

“Despite the gloomy prospects of health outcomes of any large scale nuclear event common in the minds of many, it is our mutually shared moral and ethical obligation to respond,” Dallas wrote.