Isaak Sigal

Isaak Yakovych Sigal was born on 31 March 1927 in Vinnytsia, in the Ukrainian SSR. His father, Yakiv Sigal, was an electrical engineer and his mother was a teacher. The family soon moved to Kharkiv, where his father worked for the power utility Kharkivenergo. In 1937 his father was subjected to political repression; he was rehabilitated in 1956.

In 1941, after finishing the seventh grade in Kharkiv, Sigal was evacuated with his mother to Kuibyshev (now Samara). In 1943 he enrolled at the Kuibyshev Aviation Institute and studied engine construction for three years. In 1946 he moved to Kyiv and joined the Faculty of Thermal Power Engineering at the Kyiv Polytechnic Institute directly into the fourth year, graduating as a thermal engineer in 1948.

Sigal began work at the Gas Institute of the Academy of Sciences of the Ukrainian SSR in 1949, rising from senior engineer to senior researcher. From 1962 he headed a department which, at his suggestion, was named the Department for the Protection of Atmospheric Air from Pollution. He defended his Candidate of Sciences dissertation in 1958 and his doctoral dissertation in 1971, and became a professor in 1980.

In the 1960s and 1970s he conducted the first research in the USSR on the formation of nitrogen oxides within a flame, establishing the scientific basis for how they form during combustion and founding a scientific school devoted to the subject. His group developed low-NOx burners and combustion methods installed on more than 100 power station boilers and about 900 large hot-water and industrial boilers, as well as boilers with double-sided radiant screens such as the TVG-8, KVG-7.56 and KVG-4.65. According to the institute, more than 8,500 of these boilers, with a combined capacity of about 60 GW, were in operation, around 2,300 of them in Ukraine. He also developed methods for the thermal treatment of industrial emissions from paint, varnish and woodworking plants, used at 20 enterprises and patented abroad, including in the United States.

Sigal wrote more than 380 works, including 12 monographs such as Air Protection During Fuel Combustion (1977, second edition 1988), and held more than 60 patents and inventor's certificates. He supervised 20 Candidate of Sciences dissertations and remained a leading researcher at the institute into his nineties.

Sigal married Ella Zakharivna Tovbina, a doctor specialising in paediatric and infant orthopaedics. Their son, Oleksandr Sigal, was born in 1955. Colleagues described him as a man of exceptional intellect and tolerance.

Isaak Sigal died on 20 October 2026 at the age of 99, in his 100th year. The cause of death was not made public. His death was announced on 21 October 2026 by the National Academy of Sciences of Ukraine, its Department of Energy and Energy Technologies, and the Gas Institute, which expressed condolences to his family, loved ones and colleagues. A farewell ceremony took place on 22 October 2026 in the ceremonial hall of Kyiv City Clinical Hospital No. 18 on Shevchenko Boulevard.

Sigal is regarded as the founder of the study of nitrogen oxide formation in combustion in the former Soviet Union and of a scientific school that continues at the Gas Institute. The boilers and burners developed under his leadership supply heat to millions of people and cut harmful emissions from power and industrial plants. In its tribute the institute said the scientific school he built would continue his work.