Overall, there was a decline in the total amount of air pollution in the UK, which was the result of decreases in the amounts of emissions from industrial and domestic activities. In addition, the amount of air pollutants released from transport vehicles saw an increase, surpassing the industry sector to become the most serious polluter from 2002 onwards.
Just under 8 million tonnes of air pollutants were discharged from all three sectors, with a gradual decline to 5 million tonnes at the end of the period. Simlarly, the figure for the industry sector decreased steadily from 6 million tonnes to exactly 2 million tonnes in 2005.
The amount of toxic fumes released from the transport sector started at 1 million tonnes, after which it experienced mild fluctuations at this level, before increasing from about 1,2 million tonnes in 1999 to shy of 3 million tonnes in 2005. Opposite changes, but to a lesser extent, can be seen in the figures for household activities, which contributed 1 million tonnes of air pollutants in the first 10 years, followed by a progressive drop to almost 0 in 2005.