ABSTRACT
From the moment we are born we are all surrounded by the Earth’s atmosphere. Then one of our first actions as a newborn baby is to breathe in a lungful of this atmosphere. This is a normal reflex reaction that is a vital pre-requisite for us to continue our journey of life. The atmosphere then continues to envelop us throughout our life until our ‘final breath’. The atmosphere that surrounds the Earth is an
invisible envelope of mainly gaseous substances. It is stratified into layers of different thicknesses and varying composition and we all live in the layer is closest to the surface of the Earth; this is termed the troposphere. The troposphere is approximately 8 to 15km thick (it is thinnest near to the poles and thickest near the equator). We are biologically programmed to spend all of lives within this layer of ‘air’, as we commonly call the Earth’s atmosphere. As a species, humans, as well as all the land based
living organisms that we rely upon for survival have evolved within this atmosphere. Thus it should come as no surprise that not only does the atmosphere provide the gases that are required for respiration, but it also acts as protective layer from harmful radiation and a means to regulate the temperature of the Earth’s surface. The troposphere is
the layer where the ‘weather’, as we experience it, arises and this is the process whereby freshwater is distributed across the globe. Air comprises a mixture of gases, of the order 78
per cent nitrogen, 21 per cent oxygen and 1 per cent trace amounts of other gases. (This assumes that the composition of air is both pure and dry; it is also based on volume.) The rest of this chapter refers to the addition of other substances to the air, which affect the quality of the air. We typically term this as ‘air pollution’ and it is both the causal effects of air pollution and how these are managed that is of interest to the EHP.
