The graph below shows the pollution levels in London between 1600 and 2000.

Given is a line graph illustrating the level of

sulphur

dioxide and

Smoke

per cubic metre in London from 1600 to 2000.

Overall

, the amounts of

Sulphur

dioxide were at least two times as high as those of

Smoke

over the provided period.

Similarly

, both of them constituted the same degree in the initial year, nearly 10 units.

However

,

while

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the amounts of

Smoke

increased marginally until the end of the 18th reaching the plateau at just under 500 micrograms, with a profound drop in the second half of the

17th century

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17th-century

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Sulphur

dioxide jumped rapidly through these

years

and by 1900 it consisted of two times more in the air than the first one. In the

years

that followed, their figures declined dramatically

especially

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,especially

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Sulphur

dioxides. Its level, in the next four decades, roughly halved to 500 micrograms and started to fluctuate, whilst

Smoke

began it ten

years

ago. These profound fluctuations continued for the next 30

years

comprising a negative trend. Currently, their degree is as many as it used to be in the starting year.