Commuters spend considerable time, in some cases up to 1-2 h a day, traveling in metro trains. However, few studies have compared air quality between trains traveling above-ground and underground. This study measures the PM 10 , PM 2.5 , particle number (PN) and CO 2 levels inside metro trains traveling in underground tunnels and on elevated tracks on a metro line in the Taipei metro system. The results demonstrated that PM 10 , PM 2.5 and CO 2 levels inside metro trains traveling in underground environments are approximately 20-50% higher than those in above-ground environments. However, PN levels inside metro trains traveling in underground environments are approximately 20% lower than those in above-ground ones. These measurement results reveal that levels of pollutant species inside the metro trains are significantly affected by traveling environmental conditions--in underground tunnels or on elevated tracks. Moreover, the levels of pollutant species inside the metro trains traveling on the same route are also different in different traveling directions. Fine PM inside the metro trains is transferred from the outside and significantly influenced by the surrounding conditions of the trains. Additionally, a high fraction of large coarse PM (> 10 μm) is observed inside the metro trains, possibly due to re-suspension by the movement of commuters. The measurement results show that, unlike PM, which is transferred from outside environments, CO 2 inside metro trains is elevated internally by exhalation from commuters. Clearly, CO 2 exhaled by commuters could accumulate inside metro trains and, compared to PM, is not as easily removed by the ventilation system when air circulation does not provide enough fresh air in the metro trains, particularly in trains traveling in underground environments.

Bovine lactoferrin (bLf) is a natural iron-binding protein and it has been suggested to be a prebiotic agent, but this finding remains inconclusive. This study explores the prebiotic potential of bLf in 14 probiotics. Initially, bLf (1-32 mg/mL) treatment showed occasional and slight prebiotic activity in several probiotics only during the late experimental period (48, 78 h) at 37 °C. We subsequently supposed that bLf exerts stronger prebiotic effects when probiotic growth has been temperately retarded. Therefore, we incubated the probiotics at different temperatures, namely 37 °C, 28 °C, room temperature (approximately 22-24 °C), and 22 °C, to retard or inhibit their growth. As expected, bLf showed more favorable prebiotic activity in several probiotics when their growth was partially retarded at room temperature. Furthermore, at 22 °C, the growth of Bifidobacterium breve, Lactobacillus coryniformis, L. delbrueckii, L. acidophilus, B. angulatum, B. catenulatum, and L. paraplantarum were completely blocked. Notably, these probiotics started regrowing in the presence of bLf (1-32 mg/mL) in a significant and dose-dependent manner. Accordingly, bLf significantly increased the growth of Pediococcus pentosaceus, L. rhamnosus, and L. paracasei (BCRC 17483; a locally isolated strain) when their growth was retarded by incubation at 22 °C. In conclusion, bLf showed inconsistent prebiotic activity in the 14 probiotics at 37 °C, but revealed strong prebiotic activity in 10 probiotic strains at 22 °C. Therefore, this study enables determining additional roles of Lf in probiotic strains, which can facilitate developing novel combinational approaches by simultaneously using Lf and specific probiotics.

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Traditionally, direct‐reading instruments have been used to directly determine the concentrations of indoor air pollutants that may exceed the regulation limits. However, these instruments cannot directly assess the potential health hazards of these pollutants to humans. In this study, we developed and improved a bacterial reverse mutation assay (Ames test) by using a direct gas exposure module to directly determine the mutagenicity of indoor air quality using five tester bacterial strains (TA98, TA100, TA102, TA1535, and TA1537). Thereafter, the module was used to evaluate the effects of exposure time, different concentrations of HCHO or toluene, and mutagenic activities. We found that TA100 was the most sensitive strain and was reverted by relatively lower concentrations of 0.035 ppm HCHO. Furthermore, 50 ppm of toluene exposures caused a significant increase in the number of revertant colonies of TA100 without S9 activation at the 1.5–8‐h exposure time intervals. Our findings provide new evidence that gaseous HCHO exposure could display weak but direct, time‐dependent, and dose‐dependent mutagenic activities. The weak, direct‐acting, indirect‐acting, and time‐dependent mutagen of 50 ppm toluene was also confirmed. Moreover, our improved Ames module and the exposure conditions provided in this study can be further applied to evaluate the mutagenicity of indoor air quality.

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