Efrem Lukatsky, a Kiev-based photographer for The Associated Press, recalls the confusion and anxiety of the 1986 Chernobyl nuclear power plant explosion, the world's worst nuclear accident.

In this photo taken in 1996, shows photographer Efrem Lukatsky, wearing protective clothes to reduce the radiation impact, standing in front of the sarcophagus that covers destroyed reactor No.4 in the Chernobyl nuclear power plant, in Chernobyl, Ukraine. The Chernobyl nuclear power plant explosion was only about 60 miles from photographer Efrem Lukatsky's home, but he didn’t learn about it until the next morning from a neighbor. Only a few photographers were allowed to cover the destroyed reactor and desperate cleanup efforts, and all of them paid for it with their health. I went a few months later and have returned dozens of times. (AP Photo)

The Chernobyl nuclear power plant explosion was only about 100 kilometers (65 miles) from my home in Kiev, but I didn't learn about it until the next morning from neighbor Natalia Finkel, a policeman's wife.

There's radioactive dust, she said; close all the windows and plug all the cracks. Later, my anxiety grew when I saw her husband Andrei taking off his clothes and putting them in a plastic bag before entering his apartment.

It was two full days after the April 26, 1986, explosion when the Soviet Union's tightly controlled news media acknowledged that anything had happened — and the reports' dishonesty was as bad as no news at all. The Tass news agency called it an "unlucky accident" and said there was nothing to worry about.

Nobody canceled a May Day parade in Kiev that saw thousands of people walking in columns along the streets, with songs, flowers and Soviet leaders' portraits, covered with invisible clouds of fatal radiation. A thick cloud of smoke was carrying radioactive poisons over much of Europe.

In this photo taken May 1, 1986 in Ukraine's capital Kiev, people rally to celebrate May Day a few days after the deadly explosion on the 4th unit in Chernobyl nuclear power plant. Nobody cancelled a May Day parade in Kiev when thousands of people walked in columns along the streets, with songs, flowers and Soviet leaders portraits, covered with invisible clouds of fatal radiation. (AP Photo)

The only reliable source of information was the Voice of America, but the KGB was jamming the signal. If the signal got through, we heard doctors advising us to take a daily drop of iodine to protect our thyroids from radiation.

A friend, an Institute of Nuclear Physics engineer named Viktor Ivashchenko, called me a few days after the blast and urged more me to flee Kiev and never come back. But I stayed, and went on to develop a photographic relationship with the ruined plant that lasts to this day.

Soviet authorities finally unveiled what had really happened, and let in a few photographers to cover the destroyed reactor and the desperate cleanup efforts. Initially, only three Tass photographers were allowed in: Vladimir Repik, Igor Kostin and Valery Zufarov. Repik and Zufarov later died of radiation-related illnesses and Kostin suffered from the effects for decades before dying in a car accident last year.

In this 1986 aerial view of the Chernobyl nuclear plant in Chernobyl, Ukraine shows damage from an explosion and fire in reactor four on April 26, 1986 that sent large amounts of radioactive material into the atmosphere. Only three Tass photographers were allowed in -- Volodymyr Repik, Igor Kostin and Valery Zufarov. Two later died of radiation-related illnesses, and Kostin suffered from the effects for decades before dying in a car accident in 2015. (AP Photo/Volodymyr Repik)

They were not allowed to develop the film they shot. Instead, the rolls were sent to Moscow, where the photos were edited and top-level discussions took place on which could be made public.

Kostin was with a group of "liquidators," soldiers who had been pressed into service to battle the disaster.

He climbed to the roof of the building next to the exploded reactor, firing off frames to record the soldiers who were frantically shoveling debris off the ruined structure's roof. He had to shoot fast.

"They counted the seconds for me: one, two, three ... As they said '20' I had to run down from the roof. It was the most contaminated place," he told The Associated Press in 2011. "Fear came later."

"If that explosion had occurred now and I had been told to go to Chernobyl, I would have never gone," Repik told me a few weeks before he died.

I went myself a few months later, the first of dozens of trips, as a stringer for Ogonyok magazine.

I saw crews of soldiers and firemen hastily laboring to cover the destroyed reactor with a concrete and steel sarcophagus. They had no protection from the radioactive smoke and dust except for face masks that they tore off because of heat.

In this Nov. 10, 2000 photo, an investigator points at the place of the April 26, 1986 explosion in reactor No 4 in the Chernobyl nuclear power plant, Ukraine. We reached the old control room, long and poorly lighted, with its damaged machinery, the place where the Soviet engineers threw a power switch for a routine test on that doomed night, and two explosions followed. (AP Photo/Efrem Lukatsky)

I had no protection other than a gauze mask and a white medical-style coat and head covering, all provided by the plant, which also gave us a shower afterwards.

In all, some 600,000 people took part in the cleanup operations in the first five months of the work; in subsequent years, that group has registered a markedly higher rate of cancer than in the general population.

In 2000, after I had been hired by AP, I went to mark the closing of Chernobyl's last operating reactor and got a look into the sarcophagus over the destroyed unit.

I put on two layers of thick white cotton clothes, rubber boots, a special hat and a helmet, padded jackets, gloves and a face mask.

My guide's flashlight picked up the sparkle of dust slowly whirling around us. We tried not to take any deep breaths as we wove our way through dark, wreckage-strewn passages.

We reached the old control room, long and poorly lighted, with its damaged machinery. This was the place where the Soviet engineers threw a power switch for a routine test on that doomed night, and two explosions followed.

We bent our heads to get through the dark, narrow labyrinth leading to the center of the sarcophagus. The walls were covered with lead plates intended to decrease radiation levels. There were piles of lead and boron powder dropped by helicopters to suppress the nuclear reaction.

In this photo taken on Wednesday, March 23, 2016, a worker checks radiation levels after he leaves the nuclear waste storage at the Chernobyl nuclear power plant in Chernobyl, Ukraine. The half-life of cesium-137, one of the most dangerous of the particles emitted by the explosion, is 30 years -- as long as it has been since the blast. At least three more of those half-lives will have to pass before the soil might be considered uncontaminated. (AP Photo/Efrem Lukatsky)

My Geiger counter registered about 80,000 microroentgens an hour; normal background radiation is about 23 microroentgens an hour. It was time to leave.

The half-life of cesium-137, one of the most dangerous of the particles emitted by the explosion, is 30 years — as long as it has been since the blast.

At least three more of those half-lives will have to pass before the soil might be considered uncontaminated.

The catastrophe's effects will outlive all of us who endured it.

In this 1986 photo, a Chernobyl nuclear power plant worker holding a dosimeter to measure radiation level is seen against the background of a sarcophagus under construction over the 4th destroyed reactor, Ukraine. On May 12, 1986, more than two weeks after the explosion, the leading Soviet daily newspaper Pravda published its first photograph from the site for the first time, shot three days earlier from a helicopter. (AP Photo/Volodymyr Repik)

In this photo taken on Wednesday, March 19, 1996, five-year-old Alek Zhloba, who suffers from leukemia, is held by his doctor in the children's cancer ward of the Gomel Regional Hospital, in Gomel, Belarus. There are tracks from medical procedures on his head. Much of the nuclear fallout from the 1986 Chernobyl disaster fell on Belarus. Thirty years ago, the Chernobyl Nuclear Power Plant exploded in Ukraine, spreading radioactive material across much of the Northern Hemisphere. (AP Photo/Efrem Lukatsky)

This Friday, Oct. 13, 1991 photo shows part of the collapsed roof at the Chernobyl, Ukraine nuclear power plant during a media tour of the facility, Ukraine. (AP Photo/Efrem Lukatsky)

In this Dec. 3, 1999 photo, engineer operators of Ukraine's Chernobyl nuclear power plant, the site of the 1986 world's worst nuclear accident, carry out their routine work inside the only operating third reactor, Ukraine. Shortly before Chernobyl's last operating reactor was closed in 2000. (AP Photo/Efrem Lukatsky)

In this Nov. 10, 2000, photo, the shattered remains of the control room for Reactor No. 4 at the Chernobyl nuclear power plant, Ukraine. (AP Photo/Efrem Lukatsky)

In this Nov.10, 2000 photo, radioactive contaminated vehicles lay dormant near the Chernobyl nuclear power plan. Some 1,350 Soviet military helicopters, buses, bulldozers, tankers, transporters, fire engines and ambulances were used while fighting against the April 26, 1986 nuclear accident at Chernobyl. All were irradiated during the clean-up operation. Thirty years ago, the Chernobyl Nuclear Power Plant exploded in Ukraine, spreading radioactive material across much of the Northern Hemisphere. (AP Photo/Efrem Lukatsky)

In this photo taken on Wednesday, March 23, 2016, a chimney over the destroyed reactor at the Chernobyl nuclear power plant, background left, and a gigantic steel-arch under construction to cover the remnants of the exploded reactor, are seen in the town of Prypyat close to Chernobyl, Ukraine. Abandoned houses in the foreground were left by Chernobyl plant workers a few days after the explosion, and since then Prypyat has become the ghost town. Ukraine marks the 30th anniversary of the world's worst nuclear disaster on April 26. (AP Photo/Efrem Lukatsky)

This photo taken Wednesday, March 23, 2016 shows abandoned apartment buildings in the town of Pripyat near Chernobyl, Ukraine, with a chimney, left, at the destroyed reactor and a gigantic arch-shape confinement to cover the remnants of the exploded reactor, in the back, at the Chernobyl nuclear power plant. Thirty years after the world’s worst nuclear accident, the Chernobyl nuclear power plant is surrounded by both a hushed desolation and clangorous activity, the sense of a ruined past and a difficult future. (AP Photo/Efrem Lukatsky)

In this photo taken on Wednesday, March 23, 2016, a crucifix and a radiation sign at the entrance to the out-of-bounds town Pripyat close to the Chernobyl nuclear power station are seen through a bus window. Ukraine marks the 30th anniversary of the world's worst nuclear disaster that happened in Chernobyl on April 26. (AP Photo/Efrem Lukatsky)

In this photo taken Wednesday, March 23, 2016, portraits of Soviet leaders are covered by radioactive dust in a club in the dead town of Pripyat, near Chernobyl in Ukraine. The portraits were prepared for a May Day rally in Pripyat - the town that housed the Chernobyl nuclear power plant workers - but the residents were evacuated within hours after the radioactive explosion in the fourth reactor on April 26, 1986. (AP Photo/Efrem Lukatsky)

Text from the AP story, Looking back: 30 years of photographing Chernobyl, by Efrem Lukatsky.

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