Our
senses are not attuned to this danger. You can’t
smell them, you can’t taste them and particulates
are not visible to the naked eye. They are tiny,
with a diameter not even a tenth of that of a hair.
Yet they have a major impact.
The
particles penetrate into the body through the lungs
and can cause respiratory diseases and also diseases
of the cardiovascular system. The World Health Organization
(WHO) estimates that even 10 micrograms of particulate
matter per cubic metre of air are sufficient to
cause a reduction in life expectancy of six months.
“Particulates
are now among the greatest threats to health in
urban areas”, states Dr Martin Lanzendorf of the
UFZ Centre for Environmental Research (Umweltforschungszentrum
Leipzig-Halle) of the importance of the research.
According to a recent study by the European Commission,
65,000 deaths per year in Germany are due to cardiovascular
diseases which are caused or at least intensified
by air pollution.
New
limit values
Since
1 January 2005 the new EU Directive on particulate
matter, which lays down stricter limit values, has
been in force. Particulate values must not exceed
the limit of 50 micrograms per cubic metre of air
on more than 35 days per year. Cities and agglomerations
are the areas most affected by PM10, as scientists
call it. PM stands for particulate matter and 10
denotes the particle size of 10 micrometres, that
is one hundred thousandth of a metre.
Munich
tops the table of current statistics, where the
limit has been exceeded 27 times since the beginning
of the year. In the new federal states of eastern
Germany the limit has been exceeded most often at
the Leipzig Central measuring station. So far the
upper PM10 limit has been exceeded on 15 days there.
Diesel
soot filters a first step
The
German Federal Environment Agency (Umweltbundesamt)
has identified traffic as the chief source of particulate
matter. In particular, the increase in the numbers
of diesel vehicles has exacerbated the situation
in Germany. For this reason experts from the Federal
Environment Agency are calling for the introduction
of diesel soot filters.
These
filters stop up to 99.99 per cent of the particulate
matter from getting into the atmosphere and that
could be a big step forward. This is the opinion
of the experts who met in Leipzig in February for
a workshop organised by the UFZ Centre for Environmental
Research and the Leibniz Institute for Tropospheric
Research (Leibniz-Institut für Troposphärenforschung
– IfT).
Local
authorities face difficult decisions
However,
it will be years before the majority of vehicles
are fitted with such filters. Meanwhile the towns
and cities affected must undertake measures this
year to protect the population. “If the trends seen
in the first few weeks of the year continue, several
German cities will have to take drastic action in
the summer at the latest, in order to keep within
the limit values”, said Dr Martin Lanzendorf, who
conducts research with the Sustainable Mobility
working group at the UFZ.
“This
might involve road closures, speed limits or bans
on driving diesel vehicles.” Environmental organisations
are already threatening test cases in the event
that the limit values are exceeded more often than
permitted. In 2003 this applied to one in three
of the measuring stations in Germany’s nationwide
network, although the EU Air Quality Framework Directive
was not yet in force at that time.
Ever
finer particles under the scientists’ microscopes
The
debate so far has been about PM10, particles with
a diameter of less than 10 micrometres. However,
scientists fear that the most dangerous particles
are even smaller than this. Currently there are
neither limit values nor a monitoring network for
such particles. These ultrafine particles are smaller
than 100 nanometres, that is less than one ten millionth
of a metre.
Experts
are unanimous in believing that smaller particulates
can penetrate significantly more easily and further
into the human body. “The body has a number of defence
mechanisms against larger particles”, explains Dr
Ulrich Franck of the UFZ. “However, humans have
no such defence mechanisms against smaller particulates.”
Scientists
from the GSF National Research Centre for Environment
and Health (GSF-Forschungszentrum für Umwelt
und Gesundheit) in Munich have now been able to
prove that these ultrafine particles are carried
into the blood circulation system, the heart, the
liver and other organs and can even reach the brain.
“What impacts they have there is largely unknown.
Nevertheless, initial research points, for example,
to disrupted protein reactions, that is oxidative
stress”, warns Dr Wolfgang G. Kreyling of the GSF
Research Centre. “Also, the immune system appears
to be affected in more ways than was previously
thought.”
Are
measuring techniques still adequate?
The
current measuring techniques focus on the overall
mass of the particulates. However, in the case of
ultrafine particles the issue is more about the
number of particles than the mass. Moreover, lots
of smaller particles have a larger overall surface
area, even though they weigh less.
“We
need to rethink”, says Franck, going on to mention
many as yet unsolved problems. Evidence already
exists to suggest that internal concentrations behave
very differently from external concentrations. For
three years the UFZ and the Leibniz Institute for
Tropospheric Research have been jointly monitoring
Eisenbahnstraße in Leipzig.
They
have recorded the longest continuous series of measurements
in a street canyon in Germany and this proves the
positive impact on air quality of traffic-calming
measures and speed restrictions. Parallel to this,
pollution concentrations are monitored in cooperation
with the Düsseldorf Environmental Health Research
Institute (Institut für Umweltmedizinische
Forschung) at 30 other measuring points in Leipzig,
in order to examine the links between particulates
and allergies in children.
Further
research needed
It
is clear that the number of cars will continue to
rise over the next few years and that traffic is
the main cause of ultrafine particles in cities.
But how can the dispersal of the particulates be
predicted so that effective protection for the population
can be provided? Do we perhaps also need limit values
for ultrafine particles? The new EU air quality
Directive is only one stage in the process. Scientists
and politicians will have to continue to deal with
the particulate problem in the future.
