SIFANG(SH:601126) Xin Lang Cai Jing·2026-01-24 05:10Core Viewpoint - The discussion around the carbon dioxide concentration levels in high-speed train carriages has been sparked by a viral video, with experts clarifying that the standards for train carriages differ from those for buildings, and the levels reported in the video do not pose health risks to passengers [1][2]. Group 1: Standards and Regulations - The carbon dioxide concentration control standard for passenger trains in China is set at a maximum of 2500ppm according to TB/T 3493-2017, while European standards allow up to 5000ppm [1]. - The viral claims regarding CO2 levels were based on the GB 50736-2012 standard for civil buildings, which is not applicable to passenger trains [1]. Group 2: Air Quality Management in Trains - High-speed trains are designed with a fully sealed car body, relying on an air conditioning ventilation system that provides over 15m³/h of fresh air per person, achieving air exchange rates of 6 to 12 times per hour [2]. - During normal operation outside tunnels, CO2 levels typically remain below 1500ppm; however, temporary increases can occur when trains pass through tunnels due to pressure protection measures that limit air exchange [2]. Group 3: Public Perception and Reactions - A recent video showing CO2 levels rising above 2000ppm in a second-class carriage during a journey has resonated with many passengers, leading to discussions about feelings of drowsiness associated with high CO2 levels [2][3]. - Previous discussions on social media have highlighted the correlation between increased passenger numbers and rising CO2 levels, with some passengers expressing concerns about potential hypoxia [3].