A policeman fires a teargas canister at demonstrators during a protest against Chile's government in Santiago, Chile, November 14, 2019. REUTERS/Goran Tomasevic 

An umbrella lies on the ground surrounded by the mist of tear gas during a demonstration, near government headquarters in Hong Kong, China September 29, 2019. REUTERS/Tyrone Siu 

An umbrella lies down as anti-government protesters demonstrate in Admiralty district, Hong Kong, China, September 29, 2019. REUTERS/Susana Vera TPX IMAGES OF THE DAY 

Kashmiris run for cover as Indian security forces (not pictured) fire teargas shells during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, September 6, 2019. REUTERS/Danish Ismail 

Kashmiris run for cover as Indian security forces (not pictured) fire teargas shells during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, September 6, 2019. REUTERS/Danish Ismail 

A protester gestures at the police after teargas was fired along Airport Road in Abuja, Nigeria September 4, 2019. REUTERS/Afolabi Sotunde 

A protester gestures at the police after teargas was fired at them along Airport Road in Abuja, Nigeria September 4, 2019. REUTERS/Afolabi Sotunde 

Kashmiris take cover as Indian security forces (unseen) fire teargas shells during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 30, 2019. REUTERS/DANISH ISMAIL 

Kashmiris take cover as Indian security forces (unseen) fire teargas shells during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 30, 2019. REUTERS/DANISH ISMAIL 

Kashmiris run for cover as Indian security forces (unseen) fire teargas shells during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 30, 2019. REUTERS/DANISH ISMAIL 

A Kashmiri girl reacts as a teargas shell fired by Indian security forces explodes during clashes after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 30, 2019. REUTERS/DANISH ISMAIL 

Kashmiris run for cover as Indian security forces (unseen) fire teargas shells during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 23, 2019. REUTERS/Adnan Abidi 

Kashmiris run for cover as a teargas shell fired by Indian security forces lands near them during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 23, 2019. REUTERS/Adnan Abidi 

Kashmiris run for cover as a teargas shell fired by Indian security forces explodes during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 23, 2019. REUTERS/Adnan Abidi TPX IMAGES OF THE DAY 

A Kashmiri boy stands next to empty teargas shells during clashes with Indian security forces, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 23, 2019. REUTERS/Adnan Abidi 

Kashmiris run for cover as smoke rises from teargas shells fired by Indian security forces during clashes, after scrapping of the special constitutional status for Kashmir by the Indian government, in Srinagar, August 23, 2019. REUTERS/Adnan Abidi 

A man walks past clouds of teargas during clashes after police banned planned protests over austerity and rising living costs called by the opposition Movement for Democratic Change (MDC) party in Harare, Zimbabwe, August 16, 2019. REUTERS/Philimon Bulawayo 

Protesters flee from teargas during clashes after police banned planned protests over austerity and rising living costs called by the opposition Movement for Democratic Change (MDC) party in Harare, Zimbabwe, August 16, 2019. REUTERS/Philimon Bulawayo 

A man flees from teargas during clashes after police banned planned protests over austerity and rising living costs called by the opposition Movement for Democratic Change (MDC) party in Harare, Zimbabwe, August 16, 2019. REUTERS/Philimon Bulawayo 

A man flees from teargas during clashes after police banned planned protests over austerity and rising living costs called by the opposition Movement for Democratic Change (MDC) party in Harare, Zimbabwe, August 16, 2019. REUTERS/Philimon Bulawayo 

Tear gas is seen at a children's playground outside a police station in Shatin, where protesters clashed with police officers, in Hong Kong, China August 11, 2019. Picture taken August 11, 2019. REUTERS/James Pomfret 

A man arranges teargas canisters used by security forces inside a compound in the Burri district of Khartoum, Khartoum, Sudan, July 10, 2019. REUTERS/Mohamed Nureldin Abdallah 

Men holds teargas canisters and bullet shells used by security forces inside a compound in the Burri district of Khartoum, Khartoum, Sudan, July 10, 2019. REUTERS/Mohamed Nureldin Abdallah 

Sudanese run away from teargas fired to disperse them, as they march on the streets demanding the ruling military hand over to civilians during a demonstration in Khartoum North, Sudan June 30, 2019. REUTERS/Mohamed Nureldin Abdallah 

Sudanese run away from teargas fired to disperse them, as they march on the streets demanding the ruling military hand over to civilians during a demonstration in Khartoum North, Sudan June 30, 2019. REUTERS/Mohamed Nureldin Abdallah 

Sudanese run away from teargas fired to disperse a demonstration demanding the ruling military hand over to civilians in Khartoum North, Sudan June 30, 2019. REUTERS/Mohamed Nureldin Abdallah 

An anti-government supporter sits on the ground after inhaling teargas during a protest in Tirana, Albania, June 2, 2019. REUTERS/Florion Goga 

A protester reacts to tear gas canisters fired by police at a demonstration during the Act XXIV (the 24th consecutive national protest on Saturday) of the yellow vests movement in Strasbourg, France, April 27, 2019. REUTERS/Vincent Kessler 

Protesters stand in smoke during a demonstration on Act XXIII (the 23rd consecutive national protest on Saturday) of the yellow vests movement in Paris, France, April 20, 2019. REUTERS/Yves Herman 

A demonstrator throws a stone towards Indian police (unseen) as a teargas shell fired by police explodes behind him during a protest after India's National Investigation Agency (NIA) summons Mirwaiz Umar Farooq, chairman of Kashmir's moderate faction of All Parties Hurriyat (Freedom) Conference (APHC), in Srinagar, March 10, 2019. REUTERS/Danish Ismail TPX IMAGES OF THE DAY 

A demonstrator throws a stone towards Indian police (unseen) as a teargas shell fired by police explodes behind him during a protest after India's National Investigation Agency (NIA) summons Mirwaiz Umar Farooq, chairman of Kashmir's moderate faction of All Parties Hurriyat (Freedom) Conference (APHC), in Srinagar, March 10, 2019. REUTERS/Danish Ismail TPX IMAGES OF THE DAY 

A demonstrator throws a stone towards Indian police (unseen) as a teargas shell fired by police explodes behind him during a protest after India's National Investigation Agency (NIA) summons Mirwaiz Umar Farooq, chairman of Kashmir's moderate faction of All Parties Hurriyat (Freedom) Conference (APHC), in Srinagar, March 10, 2019. REUTERS/Danish Ismail 

EDITORIAL USE ONLY - NO COMMERCIAL OR BOOK SALES. FILE PHOTO: Protesters run in panic as riot police returned to Istanbul's Taksim square late afternoon June 11, 2013. Turkish riot police fired volleys of teargas canisters into Istanbul's Taksim Square, centre of protests against Prime Minister Tayyip Erdogan, driving thousands into narrow side streets, witnesses said. EUTERS/Yannis Behrakis/File photo SEARCH "YANNIS BEHRAKIS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. 

EDITORIAL USE ONLY - NO COMMERCIAL OR BOOK SALES. FILE PHOTO: A group of riot policemen is engulfed in flames after protesters threw petrol bombs in Athens' Syntagma square during a 24-hour labour strike September 26, 2012. Greek police fired teargas at hooded youths hurling petrol bombs and stones as tens of thousands took to the streets in Greece's anti-austerity demonstration. The officers escaped with little to no injuries. REUTERS/Yannis Behrakis/File photo SEARCH "YANNIS BEHRAKIS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. 

Sudanese demonstrators run from a teargas canister fired by riot policemen to disperse them as they participate in anti-government protests in Omdurman, Khartoum, Sudan January 20, 2019. REUTERS/Mohamed Nureldin Abdallah 

Sudanese demonstrators run from a teargas canister fired by riot policemen to disperse them as they participate in anti-government protests in Omdurman, Khartoum, Sudan January 20, 2019. REUTERS/Mohamed Nureldin Abdallah 

Sudanese demonstrators run from a teargas canister fired by riot policemen to disperse them as they participate in anti-government protests in Omdurman, Khartoum, Sudan January 20, 2019. REUTERS/Mohamed Nureldin Abdallah 

Teargas is lobbed to disperse Sudanese demonstrators during anti-government protests in Khartoum, Sudan December 25, 2018. REUTERS/Mohamed Nureldin Abdallah 

Sudanese demonstrators run from teargas lobbed to disperse them as they march along the street during anti-government protests in Khartoum, Sudan December 25, 2018. REUTERS/Mohamed Nureldin Abdallah 

Sudanese demonstrators eject a teargas canister lobbed to disperse them as they march along the street during anti-government protests in Khartoum, Sudan December 25, 2018. REUTERS/Mohamed Nureldin Abdallah 

A group of men, part of a caravan of thousands of migrants from Central America en route to the U.S, pull down the border gate with the intention to carry on their journey, in Tecun Uman, Guatemala, October 28, 2018. Reuters photographer Carlos Garcia Rawlins: "This picture of men trying to pull down the Mexican border gate seems to symbolise the struggle at the heart of this story: the tension between the urge to find a better life and governments' attempts to control borders. Hundreds of migrants had gathered at dawn on the bridge that marks the border between Guatemala and Mexico. They hoped the guards would open the gates and let them pass through as they moved towards the United States. But the gates stayed locked and as the day wore on tensions rose and tempers frayed. In the early afternoon, people started to attack the Mexican border fence. A police helicopter flew overhead and riot police launched teargas canisters into the crowd, while migrants threw stones. The struggle carried on into the night but the migrants were unsuccessful and the gates remained closed. One man from Honduras died in the clashes. The following day the group started going down into the Suchiate River where they formed a human chain and crossed into Mexico. The caravan might have started as individuals but as time has gone on I've noticed a sense of solidarity growing among the group. They try to keep to the pace of the most vulnerable, people carry each other's children and share what food they have. People here are walking in hope of finding the American Dream - education, work and a better life for their children." REUTERS/Carlos Garcia Rawlins SEARCH "IMMIGRATION POY" FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2018 PACKAGES. TPX IMAGES OF THE DAY. 

Chilean dockworkers are sprayed by a riot police water truck during a protest against the port operator TPS (South Pacific Terminal) to demand that temporary workers be included in collective bargaining in Valparaiso, Chile December 17, 2018. REUTERS/Rodrigo Garrido TPX IMAGES OF THE DAY 

A woman is sprayed with teargas by the riot police officer during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman SEARCH "POY GLOBAL" FOR FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2018 PACKAGES. TPX IMAGES OF THE DAY. 

A tear gas shell fired by Indian police explodes during a protest march in Srinagar December 17, 2018. REUTERS/Danish Ismail TPX IMAGES OF THE DAY 

A tear gas shell fired by Indian police explodes during a protest march in Srinagar December 17, 2018. REUTERS/Danish Ismail 

Former President Manuel Zelaya is helped by aides while being overcome by tear gas during a protest against the re-election of Honduras' President Juan Orlando Hernandez in Tegucigalpa, Honduras January 12, 2018. Reuters photographer Jorge Cabrera: "I was covering a protest against Honduran President Juan Orlando Hernandez in the capital Tegucigalpa when things turned violent. Some protesters vandalized the front of the Marriott Hotel, and police responded with tear gas and warning shots. Among the protesters was former president Manuel Zelaya. Zelaya tried to quell the clashes but got caught in the middle of the scuffle and his hat fell on the ground. As he tried to retrieve it, Zelaya was gassed and attacked by police. The photo I took captured his bodyguards as they tried to get him to safety while Zelaya catches his breath, holding a gas mask. What struck me the most was how the former president seemed to ignore the danger - the teargas and bullets - and he appeared solely focused on getting his hat back. But police soon charged again, and Zelaya never managed to retrieve it." REUTERS/Jorge Cabrera SEARCH "POY STORY" FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2018 PACKAGES. TPX IMAGES OF THE DAY. 

Relatives of inmates held at the General Command of the Carabobo Police react as they wait outside the prison, where a fire occurred in the cells area, according to local media, in Valencia, Venezuela March 28, 2018. Reuters photographer Carlos Garcia Rawlins: "When we heard that riots and a fire had broken out in the cells of a detention centre in Valencia, we knew that it was a possible catastrophe as many prisons in the country are overcrowded. There were rumours of dozens of deaths and there was a desperate atmosphere as a crowd of several hundred people waited for news of their loved ones. Earlier in the day there had been clashes and the police had used teargas to disperse the families. Police officers were trying to update people, but no official statements had been made, and as people heard news of their relatives in the detention centre, a reaction would spread through the crowd. People were crying, fainting and shouting throughout the street. I was standing on the other side of the street when I heard a woman's scream pierce the air. I rushed through the crowd and saw this woman. She was overwhelmed by grief and people cleared a space around her and tried to comfort her. This was a really difficult moment to photograph because her pain was so intense, I don't think she even really noticed I was there. Authorities subsequently said that 68 people died in the fire, including two women who were visiting inmates. I spent the following day documenting the funerals of some of those who had died." REUTERS/Carlos Garcia Rawlins SEARCH "POY STORY" FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2018 PACKAGES. TPX IMAGES OF THE DAY. 

A woman is sprayed with teargas by the riot police officer during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman/File photo SEARCH "TEARGAS HERMAN" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY. 

Reuters photographer Yves Herman: "Usually, a golden rule for a news photographer covering a scene of angry confrontation is to get close, but not involved. Sometimes, though, it's hard to avoid. "Yellow vest" protests have in recent days spread to Belgium from France. I followed hundreds of people marching through Brussels on Saturday to demand lower fuel prices and better living conditions. They were blocked from reaching the government quarter by riot police using water cannon and tear gas. Some of the crowd hurled rocks and firecrackers at them. Police squads started surrounding protesters, sending in snatch teams to arrest individuals. As the march was organised on social media without approval from the authorities, police took the view that anyone involved could be detained and taken away. Most are quickly released without charge. When one young man was seized, a young woman with him rushed towards the line of police, shouting that he had done nothing wrong. She had no mask or helmet and nothing in her hands. She wasn't even wearing one of the fluorescent yellow vests adopted by the movement. As she yelled at a policewoman, another officer standing behind the front rank pointed and fired a pepper-spray gun, dousing the young woman in the face. The photo I took dramatically captured the white liquid's moment of impact and her anguished expression. She turned away crying and sat down on the road, her eyes and face inflamed. I had a bottle of eyewash as part of my own safety equipment. I put my camera down, asked her to look up and carefully dropped the soothing liquid into her eyes." REUTERS/Yves Herman/File photo SEARCH "TEARGAS HERMAN" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY. Matching text: BELGIUM-PROTESTS/IMAGE 

A woman is sprayed with teargas by a riot police officer during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman 

French Gendarmes run during clashes at a demonstration of the "yellow vests" movement in Marseille, France, December 8, 2018. REUTERS/Jean-Paul Pelissier 

A woman is sprayed with teargas by the riot police officer during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman TPX IMAGES OF THE DAY 

A riot police member uses teargas against a demonstrator during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman 

A woman is sprayed with teargas by the riot police officer during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman 

A woman is sprayed with teargas by the riot police officer during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman 

A woman is sprayed with teargas by the riot police officer during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman 

Police use teargas against demonstrators during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman 

Police use teargas as they clash with demonstrators during the "yellow vests" protest against higher fuel prices, in Brussels, Belgium, December 8, 2018. REUTERS/Yves Herman 

Supporters of Congolese opposition Presidential candidate Martin Fayulu shield themselves from teargas canisters lobbed to disperse them as they welcome him at N'djili International Airport in Kinshasa, Democratic Republic of Congo November 21, 2018. REUTERS/Kenny Katombe 

Supporters of Congolese opposition presidential candidate Martin Fayulu run from teargas canisters lobbed to disperse them as they welcome him from N'djili International Airport in Kinshasa, Democratic Republic of Congo November 21, 2018. REUTERS/Kenny Katombe