High levels PM2.5 at indoor air quality

Among the most serious People’s Square Station, the average concentration of PM10 reached 825ug / m3, is 3.3 times the Metro design specifications, it is indoor air quality standard 5.5-fold.

Ten years ago, we had a underground mall in the London Underground Space PM2.5 monitoring found high content of Environmental Science Professor Luo Bote accept, said Science Daily “reporters, when construction of underground space, has been installed ventilation systems, indoor air update. subway ventilation is “double protection.” “under normal circumstances, the subway ventilation are relying piston wind. Only one more concentrated, when the temperature reaches a certain level, or carbon dioxide concentration, ventilation and air conditioning system inside the subway will be open. “Luo Bote explains piston wind, is when the train in the tunnel, the tunnel is a train driven by air and train running along the direction of forward flow.

However, although the ventilation system can remove carbon dioxide, but also the when one of the causes of excessive levels of PM2.5 underground space, “because the accumulation of dust in air ducts, ventilation will be carried out of the dust. Subway poor air quality are also included in the subway tunnel dust, the wind was out of the piston. “Luo Bote, said.

Select the location measurement science, Darwin Institute of Environmental detect excessive levels of PM2.5 in the subway. “Someone to monitor air pollution, equipment used, the number of detections, there is no standardized testing, morning, afternoon detect different times, different possible outcomes, and different people, different measurement methods may not the same.” Atmospheric physics researcher Dr. Wan said, “Science News” reporter.

Ventilation system determines the wind, and the movement of people, starting the subway will affect the air flow, resulting in uneven distribution of PM2.5. Professor Luo Bote argued underground space measuring air quality, but also should be based on the location of the air source. “If you measure from the subway entrance into the air, it may be better quality, while the inflow of air from the tunnel, the poor quality.