Air
quality in Germany has improved over the years. The relative share of NOx has
decreased by 10% between 1995 and 2007, but road traffic is still by far the
largest source of emissions. However, the relative contribution by road traffic
to air pollution has reduced significantly over the last two decades. Since the
turn of the century, attention in Germany has focused on PM10, which is
produced as a by-product of road traffic and industry. Before that, the share
of traffic was 27%, while the relative share of industry was 23%. In 2007 it had
dropped to 19% for road traffic and 22% for industry.