Radiation can be a rather dangerous thing. It can cause us a host of health problems and, in high enough doses, prove fatal.

Fortunately, there are very few places on Earth where you could be subjected to enough radiation to cause you too much harm. But there are a few where it’s advisable not to spend much time.

From nuclear decommissioning sites to the locations of past disasters, several places on Earth remain off limits. And some of them are unlikely to be safe to visit in the near future.

So here are some of the most radioactive places on Earth, although there are others too. Below we've also included a handy guide to radiation doses from XKCD.

Ramsar, Iran

The first place on our list is the town of Ramsar in Iran. People in this town receive an annual radiation dose of 260 millisieverts (mSv), which is much higher than the 20 mSv allowed for radiation workers each year. An average person receives 3.1 mSv each year.

The cause of this radiation in Ramsar is nine hot springs, which bubble uranium-rich igneous rock dissolved in groundwater from below the surface. Radium from these springs enters the limestone, from which the houses are built, but it can also be found in crops and drinking water.

A study in 2002 found that these doses had caused 56 percent more chromosomal abnormalities in the 33,000 or so inhabitants of the town. Scientists have recommended that the residents relocate, but that doesn’t seem to have had much effect.

Goiania, Brazil

Back in 1987, two robbers ransacked an abandoned hospital in Goiania, mostly for scrap metal. Unfortunately, they also found a small capsule of highly radioactive caesium chloride, which had been used in a radiotherapy device.

They took the material with them, ultimately causing the deaths of four people. It’s reported that children, attracted by the bright blue of the material, also touched it and rubbed it on their skin. Several city blocks became contaminated and had to be demolished.

In the end, 300 people suffered radioactive contamination, but “radiophobia” swept through the city. More than 100,000 people queued to be screened for radiation exposure. The topsoil was removed from several sites to remove the radiation. Levels as high as 2 sieverts an hour were found in some locations, but while life has mostly returned to normal, some places still remain contaminated.

Mailuu-Suu, Kyrgyzstan

This mining town in southern Kyrgyzstan is still dealing with the consequences of the Soviet Union’s nuclear program. It was used to mine and process uranium ore from 1946 to 1967, but today remains very dangerous.

Much of the waste from the mining was buried along the river that runs through the town. A report back in 2010 said it was in urgent need of cleaning up, while high cancer rates and poor immune systems have been reported among young people there.

About 20,000 people still live here today. The dumps, known as tailing dumps, continue to threaten to contaminate drinking water. Radiation levels have been found to be beyond safe limits, but while some families have been relocated, others remain.

Sellafield, UK

Found on the western tip of the UK, Sellafield is a nuclear decommissioning site where you’ll find high levels of radiation. This is where most of the radioactive waste from the UK’s 15 operational nuclear reactors are stored, while it also reprocesses nuclear fuel from overseas.

The waste produces radiation levels of up to 280 sieverts per hour, which is 60 times the dose that is fatal. Dissolved fuel rods are stored in a giant storage pool underground, called the Head End Shear Cave. Only robots are sent into the cave.

The site is safe enough to work there, but as nuclear fuel continues to be stored in the cave, it is probably not the best place to visit.

Hanford, US

The Hanford Site, which is a decommissioned nuclear production complex, is commonly said to be the most radioactive place in the US. It was once used to produce plutonium for the Manhattan Project, and today it still stores 65 percent of the country’s radioactive waste.

In May 2017, a tunnel collapse at the plant caused major concerns, with workers told to evacuate. Huge amounts of soil were reused to block up the tunnel. There have also been environmental concerns with the surrounding environment.

Just recently, in February 2018, some vehicles used on the site were found to contain Americium-241 in their air filters. Contamination has also been found up to 16 kilometers (10 miles) away from the site.

Chernobyl, Ukraine

The Chernobyl disaster back in 1986 was caused when one of its reactors failed. A power surge blew the top off the reactor, leaking out huge amounts of radiation. Much of it spread to Belarus, Ukraine, and into the rest of Northern Europe.

About 116,000 people were relocated as a result, including those from the nearby town of Pripyat. Today, you can visit Chernobyl, but pockets of radiation around the site remain.

In 2017, a huge steel tomb was placed over the damaged reactor, which will now seal it for a century to prevent any further leaks. The plant itself remains off limits though due to the high levels of radiation, and it may be decades before people can return to the surrounding area.

Pripyat Hospital, Ukraine

Several miles from the Chernobyl power plant you’ll find Pripyat Hospital, where the first responders to the Chernobyl disaster were taken. As Derek Muller explains in this excellent video for Vertasium, this hospital still contains some of the highest radiation levels you can visit in the world.

It was here that firemen were taken after they fought the blaze at the reactor. In the basement, their clothing had been left once it was realized how contaminated it was. This clothing remains highly radioactive.

“Right outside the door I’m getting 500 microsieverts an hour,” Muller said in his video. Nearer, the clothing levels surpassed 1,500 mSv. “If we stayed here for a couple of hours we’d receive our annual dose of background radiation.”

Muller said it was one of the most radioactive places he's visited, and it remains one of the most radioactive places on Earth.

Fukushima, Japan

In 2011, a tsunami knocked out the power to the Fukushima Daiichi nuclear plant in Okuma, Japan, causing three of its six reactors to go into meltdown. About 160,000 people were evacuated from the surrounding area as a result, and they have little chance of ever returning.

Radiation levels inside the planet have been found as high as 530 sieverts per hour. That’s more than enough to kill a human, and it’s caused plenty of robots sent inside to fail. Japan has been using these robots to try and find the melted fuel from the reactor.

Over the past year, they’ve been mildly successful, locating fuel in two of the three reactors. Once all the fuel has been found, the decommissioning process can begin. This is expected to take about four decades, at a cost of about $188 billion. Fukushima won’t be a safe place to go any time soon.