The line graph illustrates the amount of air pollutants emitted from four sources—transport, industry, households, and the total level of pollutants—in the UK between 1990 and 2005, measured in million tonnes.
Overall, the total amount of air pollutants, along with emissions from industry and households, showed a steady decline throughout the period. In contrast, emissions from transport experienced a gradual increase, despite starting at the same level as households in 1990.
In 1990, the total volume of air pollutants was the highest at approximately 7 million tonnes. This figure dropped significantly over the next 15 years, reaching around 3 million tonnes in 2005. A similar trend can be seen in industrial emissions, which decreased from 6 million tonnes in 1990 to just above 2 million tonnes in 2005.
Household emissions started at 1 million tonnes in 1990, fell to around 0.5 million tonnes by 1996, slightly rose to about 0.7 million tonnes in 1999, and then steadily declined to under 0.2 million tonnes by the end of the period. On the other hand, transport emissions followed an opposite trajectory, increasing from 1 million tonnes in 1990 to nearly 1.2 million tonnes in 2005.