The chart illustrates three causes of air pollution in UK from 1990 to 2005. On the vertical axis is considered the amount of pollution in the air in million tonnes, while on the horizontal axis can be found the years in which data were registered. In addition, the different colours of the lines represent the variety of sources, so yellow means households, grey transport, orange industry and blue is obtained from all the previous and represents the totality.
On one hand, there is a downward trend for pollution caused by households and industry. The former remained the same from 1990 to 1999 and since early 2000s has begun to decrease. In contrast, the latter has been decreasing gradually since 1990, but sometimes it went down sharply, for example between 1999 and 2002.
On the other hand, there is evidence of an upward trend regarding transport. As a matter of fact, it increased from 1996 to 2005, but an exception has to be made concerning 6 years between 1990 and 1996, during this period it fluctuated a little.
All things considered, the average trend represented by the blue line is negative, that is a positive data for air pollution, instead. From 1990 to 2005 the quality of the air improved so much that from 8 million tonnes of pollutant it got to less than 5.