Indoor air quality assessment with respect to culturable airborne bacteria, total volatile organic compounds, formaldehyde, PM 10 , CO 2 , NO 2 , and O 3 in underground subway stations and parking lots

We measured the concentrations of indoor pollutants (fine particulate matter (PM 10 )), culturable airborne bacteria (CAB), total volatile organic compounds (TVOCs), formaldehyde (HCHO), CO 2 , NO 2 , and O 3 in subway stations and public parking lots at a national scale in South Korea in order to determine their possible relationships with other underground environmental factors and facility characteristics. Indoor pollutants were sampled at 59 underground facilities with a total of 187 samples in subway stations and parking lots. Kruskal–Wallis and Mann–Whitney analyses were used to examine the relationships between atmospheric pollutants at underground facilities and indoor/outdoor differences in PM 10 and O 3 concentrations. Underground PM 10 concentrations were higher than outdoor concentrations at all underground facilities ( p < 0.001), while underground O 3 concentrations were lower than outdoor O 3 concentrations at all underground facilities ( p < 0.001).