PM 2.5 and DEP Airborne Particulate Matter
(Urban Air Pollution)
Homepage: http://www.nies.go.jp/pmdep/index-e.html
More than seventy-two million vehicles are officially registered in Japan (excluding motorcycles). In large cities where traffic is concentrated, air pollution is reaching serious levels, mainly caused by vehicles. The health impacts of airborne fine particulate matter (known as PM2.5), and diesel exhaust particles (DEP), are matters of particular concern. NIES is conducting research into issues ranging from the generation of DEP and PM2.5 to levels of human exposure to these particles, and studying their health impacts.
Japan has been able to significantly reduce urban air pollution from sulfur dioxide, which is mostly emitted from factories. However, there has not been adequate improvement in levels of nitrogen dioxide and other substances from vehicles, which account for more than half of the pollution.
In addition, particles smaller than 2.5 microns in diameter (known as PM2.5), found in diesel exhaust particles (DEP) and other particulates, have been linked to respiratory ailments and higher mortality. Accordingly, the health impacts of these particles have become a new matter of concern. Five teams at NIES are conducting research in order to rapidly improve scientific knowledge regarding PM2.5 and DEP, and aiming to connect the knowledge obtained with the development of countermeasures.
Identifying the Emission
Sources and Considering Response Scenarios
NIES is carrying out research to help clarify the physical and chemical
properties of DEPs using testing facilities for low emission vehicles.
We are taking measurements of the process, from the generation of DEP
to the emission into the atmosphere, under meteorological conditions that
are as close as possible to reality.
Environmental testing
room and chassis dynamometer equipment, part of the testing facilities
for low emission vehicles
In addition, in order to accurately identify the emission sources of
the pollution, we are estimating the geographical distribution of sources
based on experimental data obtained from our testing facilities as well
as data on economic activity. 
Estimated distribution
of emissions of diesel exhaust particles from trunk roads
Furthermore, in order to solve environmental problems caused by urban
transportation activities, we are carrying out research relating to assessment
methodologies for the effectiveness of various types of countermeasures,
such as increasing the use of low-emission vehicles and alternative transportation
systems.
<Transportation Pollution Control Research Team>
Predicting the Future Based on Today's Air Pollution
In order to clarify the behavior of airborne particulates such as PM2.5,
we are conducting research to explain various phenomena and developing
models. We are studying combinations of gaseous air pollutants and aerosols,
and using field observations, computer simulations and wind tunnel experiments.
Wind tunnel experiment
using a 1/300 model of an actual urban area
These help to study the diffusion of air pollutants by recreating the
complex air flows through cities.
<Urban Air Quality Research Team >
Developing New Measuring Methods
We are developing new techniques to make measurements of particulates.
For this, multiple approaches are used, taking into account not only the
properties of each type of particulate such as the size and chemical composition
of DEP and PM2.5, but also their spatial concentrations and changes over
time.
<Aerosol Measurement
Research Team>
Mobile monitoring system
for PM2.5/DEP particles
Measurement principle: light diffusion method. Diameter of particles measured:
0.3-5 m (4 size classes). Data transmission: uses cellular telephone.
Features: data can be obtained simultaneously from many locations, in
real time.
Identifying Human Exposure Levels and Health
Effects
We are researching the extent of human exposure to particles such as PM2.5
such as DEP.
Example of exposure
assessment using geographical information system (GIS)
Calculates the exposed population according to level of pollution concentrations,
using road and other sources of emissions of air pollution plus a diffusion
model, and superimposing this on the population distribution.
In addition, we are conducting research to estimate PM2.5 concentrations
for each region of Japan based on knowledge about atmospheric dynamics
and amounts of PM2.5 emitted from diesel-powered and other vehicles. Other
work includes estimating the exposed populations in each area for each
level of PM2.5 concentration, based on population distributions. This
work uses geographical information systems (GIS). We are also analyzing
data on vital statistics in various regions, considering the statistical
correlations between exposure levels and mortality rates, and carrying
out a variety of epidemiological studies.
<Epidemiology and Exposure Assessment Research Team>
Investigating Toxicity
We are conducting research about the toxicity of DEP and PM2.5, by directing
diesel engine exhaust and other substances into a chamber, and studying
the impacts of long-term exposure on animals such as rats and mice.
Lungs of a rat after
exposure to diesel exhaust. Compared to the normal pink lung, it has been
blackened by soot.
In addition, we are carrying out comprehensive and systematic experiments
on organs of individual animals such as the lungs and heart, with the
aim of clarifying the impacts of diesel emissions on respiratory and circulatory
organs.
<Toxicity/Impact Assessment Research Team>
Exposed
to diesel exhaust
Exposed to clean air
Testing is done by
applying a certain load to this diesel engine, exposing a laboratory animal
to the exhaust, and determining the effects.
