The line charts illustrate varied air contaminants in the United Kingdom between 1990 and 2005.
Overall, almost all sources of emissions witnessed a downward tendency, except for transportation. Notably, the figure for emissions of industrial activities accounts for the majority of the total, while those for households were the lowest over the period.
The total figure of air contaminants exhibited a consistent plummet from 7 million tonnes to nearly 5.5 million tonnes in the first 9 years, then stabilized in the following 3 years before continuing to decline to 5 million tonnes by 2005. In 1990, around 5.5 tonnes of pollutants from the industry had been released, this number slowly descended to roughly 5 million tonnes in 1993. Subsequently, it undergoes a significant plunge in the next 9 years, and finished at 2 million tonnes in 2005.
Concern about households and transport, the amount of emitted substance in household also observed a similar tendency, but with a lesser extent. In the first 3 years, this number had been stabilized at 1 000 000 tonnes, which fell by a half in 3 years later; then it recovered to approximately 0.75 million tons in 1999 before went to its lowest point in 2005 with relatively low figures. On the other hand, transportation remained unstable, but the number barely changed over the time. From the 90s to 2002, it showed insignificant shift, and hit a plateau at 1 million tons afterwards.