Not surprisingly, city centres show the highest levels
of PM10's. London is particularly high. One estimate says
that nearly 80% of the PM10's in London come from traffic
A level of 50 microgrammes has been set as a safe maximum,
but long term exposure to lower levels could damage health.
These are the average levels over a year. This means there
will be some times when
the levels are higher than
they are in the graph.
Could this cause serious
health problems? Levels
in central London have
been known to reach over
80 microgrammes per cubic