The mean 24-hour TWA of 168 μg/m3, and mean exposure levels
in all locations, were very high compared with the World Health Organization
recommendation of a maximum 24-hour mean of 25 μg/m3 for
PM2.5 and 50 μg/m3 for PM10 (WHO, 2011) and also higher than the National
Ambient Air Quality Standards for Nepal recommendation of
120 μg/m3 for PM10 (Central Bureau of Statistics, 2012b). Similar
high microenvironment concentrations have been reported by others
in the Himalayan region of northern India (Saksena et al., 1992), and
Malawi (Fullerton et al., 2009).