Fog-haze and smog can be formed in transport tunnels during artificial cooling by air-conditioner, under hot and high humidity conditions inside a coal mine. The processes of coagulation, condensation, nucleation, crushing and evaporation, which can occur at the same time, can be simulated by a dynamic model. The relationship between the particle size distribution over time and environmental parameters such as wind speed, temperature and relative humidity, during smog formation in transport tunnels in a coal mine was characterised by our numerical modelling and in-situ study of a coal mine in Hunan Province, China. The development and dissipation of fog-haze and smog when under cooling inside a deep coal mine were modelled using multiple Monte Carlo algorithm method validated by our experiment using a 1 m 3 wooden chamber. Our numerical modelling was confirmed by our in-situ measurement results, indicating that (1) the bigger the condensation coefficient would lead to a faster formation of aerosol particles giving larger number and sizes of particles; (2) faster wind speed would reduce the number of aerosol particles and increase the geometric mean of the particle diameter. (3) When cooling in the tunnels, 2 m/s would be the lowest wind speed that could disperse the haze in the transport tunnels in the mine. The findings of our research should provide the theoretical basis for artificial cooling and controlling of the formation of haze in transport tunnels for mining.
A field investigation on indoor environmental conditions was performed in homes with primary school children in Changsha, a city located in central-south China. The main purpose is to obtain more reliable and comprehensive data relating to the health of children. The results showed that the average temperature, relative humidity and carbon dioxide concentration in October were 20.4°C, 56.7% and 398 ppm, while in January were 10.5°C, 55% and 475 ppm, respectively. The monitored PM2.5 concentrations were greater than the Chinese national standard GB 3095–2012 (75 μg/m3), with a significant difference found between October and January ( p < 0.05). Carbonyl compounds were much lower than the corresponding specified limits. However, total volatile organic compounds (TVOCs) in some homes in January exceeded the Chinese standard GB/T 18883–2002 (600 μg/m3). The most common constituents of semi-volatile organic compounds in house dusts were di(2-ethylhexyl) phthalate and dibutyl phthalate. Furthermore, Cladosporium, Penicillium and Aspergillus were all found in indoor air and house dusts. Children’s daily intake of formaldehyde, acetaldehyde and TVOC were primary from their bedrooms rather than living rooms ( p < 0.05). These results would contribute to the public awareness of indoor environmental conditions and possible impacts on school-age children in their homes.
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