The line graph delineates the changes in four contributors to air contamination in the UK over the period from 1990 to 2005, at three-year intervals, measured in million tons.
Overall, a downward trend can be observed throughout the period, except for transport. While total air pollutants consistently remained the dominant category, transport experienced the most dramatic change and eventually overtook households. By contrast, households remained the lowest throughout the timeframe.
In 1990, total air pollutants emerged as the leading category, standing at nearly 7 million tons, while industry followed at approximately 5,5 million tons. By comparison, the figures for transport and households were far less significant, at the same 0,7 million tons. However, the subsequent years witnessed substantial changes in the pollutants released from different sources. While total air pollutants declined significantly, industry followed a similar trajectory, eventually reaching 3,5 and 2 million tons respectively by 2005.
In contrast to the trends observed in two aforementioned sectors, transport followed a different pattern throughout the timeframe. Although starting from a relatively low base, transport fluctuated slightly, eventually overtaking households by 1993. By the end of the timeframe, total air pollutants had consolidated its position as the dominant category at approximately 3,5 million tons, whereas households remained the lowest, standing at only around 0,4 million tons.