Deep caves, too, could contain relatively pollution-free air, so long as they didn't have much circulation with the outside world.
Our objective is to study the diurnal variation of fair-weather electric fields at a relatively pollution-free place, and to find out the extent to which the measured field represents the universal Carnegie fields.
Further, they are also better able to avoid suffering the harmful health consequences of pollution by living and working in relatively pollution-free environments.
In addition, the country's diverse geology, numerous exposed rocky crags and screes and deep, damp ravines coupled with a relatively pollution-free atmosphere enables a diversity of species to exist.
Freshwater ponds are contained, so there are no "escapes" (which can spread disease to wild fish) and relatively little pollution.
If it's located in the countryside, which enjoys relatively low pollution, a company can get away with its emissions, unlike one in a crowded industrial area.
Although India would rank second behind China for total emissions, unlike China and other large emitters it has not set a date by which they would peak, while new coal-fired power and other new infrastructure would commit the country to relatively high pollution levels for decades.
Although coal, biomass (crop straw and wood), and petroleum combustion were identified to be the major emission sources for most of the sampling sites, the areas with relatively severe pollution with ∑18MPAHs resulted from the localized hotspots of petroleum leakage.
Besides the mutual dissimilarity among other clusters (1-2) and (3-4) have relatively low pollution status as compared to correspondence.
MDTs [1, 2] and [2, 1] were most similar to our referent group (MDT [1, 1]) both in terms of relatively low pollution levels and meteorology.
