Credit: Min Hu

Xiaoyan Tang, Professor at Peking University, Member of the Chinese Academy of Engineering, Founder of Atmospheric Environmental Chemistry in China, and internationally renowned environmental scientist and atmospheric chemist, passed away on June 11, 2025 in Beijing at the age of 93. Professor Tang dedicated herself to the course of environmental protection and the development of environmental disciplines, making outstanding contributions to both national environmental protection and global environmental governance.

Born in Shanghai with ancestral roots in Taicang, Jiangsu, China, Xiaoyan received her early education at Shanghai Private Yunzhong Girls’ High School, then entered Yenching University in 1950 and obtained bachelor’s degree in chemistry at Peking University. She pursued graduate studies in inorganic chemistry under the mentorship of Professor Fu Ying. From 1959 to 1960, she conducted advanced studies at the Institute of Geochemistry and Analytical Chemistry of the USSR Academy of Sciences. From September 1985 to September 1986, she served as a visiting researcher at the Brookhaven National Laboratory and the National Center for Atmospheric Research in the United States.

Xiaoyan started her career as a Faculty at Peking University in 1954. She relocated with the department to a remote town in Hanzhong city, Shaanxi province in 1969, where she built the undergraduate program of Environmental Analytical Chemistry in 1972, the year when central government of China sent delegation to the United Nations Conference on the Human Environment, Stockholm. She was appointed Director of the Center for Environmental Sciences at Peking University in 1985 and was elected as an Academician of the Chinese Academy of Engineering in 1995.

In 1977, Xiaoyan pioneered groundbreaking research on a unique air pollution issue in Xigu District, Lanzhou city, Gansu province. She was the first researcher to conclude that photochemical smog pollution occurred in the petrochemical town in Northwest China. Leading an interdisciplinary team, she spent nearly a decade developing the methodology with integration of field observations, laboratory simulations and numerical modeling. She played a leading role in formulating photochemical oxidant index and measurement methods in the first national air quality standards of China. In the 1980s, she investigated the features of acid deposition and proposed a bold hypothesis on the possibility of transport-type acid rain in China. Through efforts of more than 15 years, her team employed aircraft, mountain, and ground-based observations, along with a self-developed acid deposition model, elucidated the large-scale regional transport of acid rain, and revealed the critical role of atmospheric oxidants in the transport of acidifying substances. These contributions were pivotal in China’s acid rain control strategies.

She spearheaded air quality improvement actions, leading a series of research initiatives such as the Beijing Blue Sky Project, Beijing Air Pollution Control, and the Air Quality Assurance Plan. For the Air quality program of 2008 Beijing Olympics, she organized a team to perform a study on air pollution across six provinces in northern China. The Air Quality Assurance Plan she formulated for the 2008 Beijing Olympics was ratified by the State Council and successfully implemented. Notably, with the insight in coupling of PM2.5 and ozone formation, her theory of air pollution complex was proposed in 1997, which was later designated as a key research theme in China’s Medium- and Long-Term Science and Technology Development Plan (2006–2020), becoming a core and cutting-edge focus in atmospheric science and shaping the direction of environmental research.

In response to global ozone layer depletion, she pioneered from the 1980s on the chemical mechanisms, environmental effects, and alternatives for ozone-depleting substances. In the 1990s, she served as Co-Chair of the Environmental Effects Assessment Panel under the United Nations Environment Programme (UNEP) for the Montreal Protocol, leading the development of China’s most critical technical and policy support team for the protocol’s implementation. She chaired the drafting of the China National Plan for Phasing Out Ozone-Depleting Substances, which was approved by the State Council in 1993, and became a template for other developing countries.

Xiaoyan was also a revered educator and mentor. For over 70 years, she upheld the principle of preserving tradition while fostering innovation in talent cultivation, inspiring students with creative thinking and a commitment to solving national challenges. As Chair of the National Teaching Advisory Committee for Environmental Science, she played a key role in establishing China’s higher education system for the major of environmental science. In 1972, she designed an environmental curriculum and lectured new courses including Introduction to Environmental Science, Waste Treatment, Environmental Chemistry, and Atmospheric Chemistry. Starting in 2008, she opened a new undergraduate course Environmental Issues at the age of 76. Her edited textbook Atmospheric Environmental Chemistry received top honors from the Ministry of Education, the National Environmental Protection Agency, and the Beijing Municipal Government. In 2012, Peking University established the Tang Xiaoyan Environmental Science Innovation Scholarship of Peking University to encourage young scholars to pursue careers in environmental protection.

Prof. Tang’s career was always closely aligned with China’s environmental needs. Her groundbreaking research laid the foundation for the discipline of Atmospheric Environmental Chemistry in China as well as left a profound impact on global environmental governance.