The line graph illustrates the amount of air pollutants produced by four different sources in the UK between 1990 and 2005, measured in million tonnes.
Overall, it is clear that total air pollutants and emissions from industry declined significantly throughout the period, while those from transport and households remained relatively low and stable. Industry and transport were the main contributors to air pollution, whereas households produced the least amount of pollutants.
In 1990, the total level of air pollutants was around 7 million tonnes, the highest figure shown on the graph. This number fell steadily to about 4 million tonnes by 1999 and continued to drop slightly to just under 4 million tonnes by 2005. A similar downward trend can be seen in industrial emissions, which decreased sharply from approximately 5.8 million tonnes in 1990 to around 2.8 million tonnes in 1996, before falling gradually to about 2 million tonnes at the end of the period.
In contrast, transport emissions fluctuated slightly but remained at around 1 million tonnes overall. Household pollution also showed small changes, starting at roughly 1 million tonnes, rising marginally in the mid-1990s, and then declining to become the lowest among all sources by 2005.