“一坐高铁就犯困”，铁路专家回应网传“高铁二氧化碳超标”

Core Viewpoint - The reported CO2 concentration levels in high-speed train carriages have sparked public concern, but experts clarify that the standards for CO2 levels in trains differ significantly from those in buildings, and the levels observed do not pose health risks to passengers [1][2]. Group 1: CO2 Concentration Standards - The CO2 concentration control standard for passenger trains in China is set at a maximum of 2500 ppm according to TB/T 3493-2017, while European standards allow up to 5000 ppm [1]. - The viral video referenced CO2 levels based on GB 50736-2012, which applies to buildings and not to passenger trains [1]. Group 2: Air Quality Management in Trains - High-speed trains are designed with a fully sealed car body, and air exchange is managed entirely by the air conditioning system, providing over 15 m³/h of fresh air per person [1]. - The air exchange rate in these trains is between 6 to 12 times per hour, and they are equipped with a pressure protection system to manage air quality [1]. - During normal operation outside tunnels, CO2 levels typically do not exceed 1500 ppm, but can rise temporarily above 2000 ppm when passing through tunnels due to pressure protection measures [2].