Two days before Joanna Toole, a United Nations fisheries consultant, boarded an Ethiopian Airlines flight from Addis Ababa, Ethiopia, to Nairobi, Kenya, she tweeted that she was happy to be among an increasing number of women working for the United Nations Food and Agriculture Organization.
“Great to be part of the growing number of women” working on fisheries issues, she wrote, adding a hashtag referring to International Women’s Day.
On Sunday, Ms. Toole, from southwest England, was among at least 22 people who worked for United Nations-affiliated agencies who were killed when the Kenya-bound flight crashed after takeoff. The crash killed all 157 people aboard and raised questions about the safety of the model of aircraft, the Boeing 737 Max 8.
The crash — of a flight that had been nicknamed the “U.N. shuttle” because of how often United Nations staff members take it — has also highlighted the organization’s work in some of the world’s most troubled regions, from South Sudan to North Korea.
The United Nations said its staff members on the flight had worked with several agency programs and affiliated organizations, as well as United Nations offices in Kenya and Somalia.
The United Nations secretary general, António Guterres, offered “heartfelt condolences” to the families and loved ones of the United Nations staff members who died in the crash. He also said in an email to staff that flags at United Nations offices would fly at half-mast on Monday to honor the victims.
The World Food Program said seven of its staff members had died in the crash, the most of any United Nations organization. The program’s work focuses on widespread hunger caused by war or instability in Nigeria, South Sudan and Yemen, among other countries.
“As we mourn, let us reflect that each of these W.F.P. colleagues were willing to travel and work far from their homes and loved ones to help make the world a better place to live,” David Beasley, the head of the program, said in a statement. “That was their calling, as it is for the rest of the W.F.P. family.”
The World Food Program victims included Ekta Adhikari of Nepal, who had worked for the program in Ethiopia; Michael Ryan of Ireland, who had helped Rohingya refugees in Bangladesh prepare for seasonal monsoons; and Zhen-Zhen Huang of China, who had worked in Pyongyang, the North Korean capital.
“I cannot imagine the loss felt by your loved ones, especially your son,” one of Ms. Huang’s colleagues, Faizza Tanggol, wrote on Twitter.
Other victims of the crash had been traveling to United Nations events. One was Sebastiano Tusa, an underwater archaeologist from Italy who had been traveling to Kenya for a Unesco conference about safeguarding underwater cultural heritage in Eastern Africa.
Others, including Ms. Toole, were traveling to the United Nations Environment Assembly, a meeting in Kenya this week focusing on issues like sustainable development and environmental challenges related to poverty, natural resources and waste management.
Another person traveling to that gathering was Victor Tsang, a gender expert from Hong Kong who worked for the United Nations Environment Program in Nairobi. According to his biography on the Environment Program website, Mr. Tsang had worked in Chad, Ethiopia, Panama and South Sudan.
A Twitter account that appears to be Mr. Tsang’s says that while his profession was working on sustainable development, his passion was camping with his 2-year-old son in the family’s garden. His penultimate Twitter post appears to show him dancing with colleagues on Valentine’s Day to celebrate sustainable development.
“Victor was so dedicated, and a dear colleague,” one of his former colleagues in Nairobi, Oona Tully, wrote on Twitter.
Ms. Toole, the fisheries expert from England, had been traveling to the Environment Assembly to represent the Food and Agriculture Organization’s Fisheries and Aquaculture Department, Manuel Barange, the department’s director, wrote on Twitter.
Ms. Toole, 36, was from Exmouth, in the southwestern English region of Devon. The Exmouth Journal reported that she had attended a local community college before studying animal behavior at the university level.
“Everybody was very proud of her and the work she did. We’re still in a state of shock,” her father, Adrian Toole, told the local news site Devon Live. “Joanna was genuinely one of those people who you never heard a bad word about.”
Ms. Toole, who had kept homing pigeons and pet rats as a child, often posted on social media about initiatives to protect animals from marine pollution and make the fishing industry more environmentally friendly.
Her father retweeted her penultimate post, about her friend who was paddle boarding around the Maldives to raise money for turtles affected by derelict fishing gear.
Mr. Toole’s next retweet was of a post on the same day by the Dalai Lama, the exiled Tibetan spiritual leader.
“We won’t bring about peace in the world merely by praying for it; we have to take steps to tackle the violence and corruption that disrupt peace,” the Dalai Lama wrote. “We can’t expect change if we don’t take action.”