Although subway system offers great advantages in metropolitan cities, it also suffers from indoor air quality (IAQ) problems, particularly in underground subway stations, causing the concerns on public health. In the case of the SMS, some stations are equipped with real-time tele-monitoring systems (TMS) for measuring the indoor air pollutants and the data set collected was used to develop the prediction model and validate IAQ sensors. It is reported the risks generated from carbonyl compounds analyzed in Shanghai’s subway system. Previous study has reported, the major chemical species of underground subway particles to be Fe-containing species, and airborne particles collected by permanent magnets, so called magnetic particles, turned out to be iron metal at underground station of the SMS. In particular, the concentration and properties of the particulate matter (PM) have attracted much public attention.
Previous in vitro toxicological studies have demonstrated cytotoxicity, damage to DNA, and the inhibition of the immune system caused by PM. Public health related studies have reported an increase of cardio-respiratory illnesses and morbidity, and a decreased life expectancy in individuals who have been exposed to PM. Some studies have even warned that subway PM is more toxic than other types. In underground subway stations, the concentration of PMx, including PM10 and PM2.5 size fraction, is known to be higher than in outdoor environment. This finding was observed to be the case in Seoul.