Overview
The emission of solid dust particles suspended in the air (particulate matter - PM) caused by vehicle operation have provable negative effects on human health, especially in big cities with heavy traffic. Long-term exposure to their effects shortens expected lifespan through heart and lung diseases.
Acquired data on the concentration of various suspended particles' fractions in the air on the locations burdened with traffic, including their qualities and health effects, were supposed to provide national administration authorities and professional public with initial outline of air pollution status in these locations.
Worked-out guidelines should have enabled national administration authorities, legislative organs and other subjects active in the field of transport to take appropriate actions to reduce the negative impacts of dust caused by traffic.
Primarily transport technical data (fuel consumption, traffic flow, fleet composition, road surface quality, tyres etc.) have been used as the groundwork materials characterising PM sources during the project's execution phase.
Data on housing development (on one/both sides, height zoning) and meteorological data define the conditions for particles' dispersion and propagation in the space.
Demographic data (number, geographical distribution, age structure of the residents) then served as the input conditions to calculate the ratio of exposed inhabitants.
Funding
Results
The result of the project is a dataset that has led to a guideline proposal in order to secure reducing the air pollution load by suspended particles from transport, including procedures for obtaining dustiness data, their evaluation and proposals for recovery measures.
Detailed mathematical descriptions of PM from transport, fall-out and resuspension have been produced within computer modelling and further used during creation of a complex numerical model for monitoring of the regions.
The local background concentration of PM10 reaching 45 g.m-3 has been derived from the results of executed measurements in the given location.
The computed value equals 52.2% of the measured value. Similar results have been achieved by calculating particle concentrations for different wind directions. Significantly lower PM10 concentrations achieved by calculation using regional model match with the results of available scattering studies stating that 50-70 % of PM10 concentration in Brno city centre originates from other, so far correctly unquantified sources. So called "unspecified resuspension" of the dust particles related to construction works and loessial nature of the soil cover in Brno vicinity is considered to be the most probable source in this case. Based on inverse modelling, the highest PM production has been determined in the city centre with the heaviest road traffic. The calculated value of particle production is approximately double the production determined directly by modelling (using emission factors and road traffic load) which corresponds to the results published in the literature.
Technical Implications
Transport of PM from the sources to the receptors has been explained and correlation between inner and outer environment has been set by virtue of CFD computer modelling.
The results were the current fields - flow patterns in selected areas and models of PM transport and deposition on individual locations. Height distribution of the deposition, necessary for examining the relation between outer environment and inner environment of the buildings that are part of the area and that can be influenced by PM transport, has been also obtained.
The results of PM concentration measurements at selected locations indicate long-term development trends of PM2.5 contents.
The lowest concentrations of the particles have been recorded in the summer months (May-August), the highest ones on the contrary during cold months of 2005. The presence of urban vegetation and development was also apparent, as they prevent PM from travelling over longer distances. This tendency reflects the dependence of PM2.5 concentrations on the temperature. This fact is also supported by correlation coefficient among the monitored values.
The difference in concentrations can be caused by:
- the loss of PM volatile components in the summer months,
- better ventilation in the warmer period (convection) when the particles are scattered better, while the ventilation is limited during the colder months (inversion) and PM "pile up" in the lower layers of the atmosphere, close to the place of their origin
- local furnaces / heating, especially in the winter period.
The results of calculations and simulations at the model intersection make it clear that the weather conditions critically influence the nature of concentration fields.
Moving vehicles affect the concentration field to a lower extend and their influence increases as the wind speed slows down.
Policy implications
Relations between suspended dust particles' concentration level and impacts on human health have been established, based on epidemiologic studies.
This project have culminated in the proposal of a methodical instruction about precautions, which should lead to decrease of dustinees in the atmosphere caused by traffic and herewith also reduction of negative influences on the human health.
Model localities that represent the environment with different burden were chosen for measurements of distribution and environmental fate of particulate matter in the atmosphere.
Samples were taken according to Directive 350/2002 Collection of law during week-long campaigns. Obtained results of PM concentrations indicate long term development trends of their concentrations. A computer model of chosen localities with specific sources of PM was created and immuno-assays of population sample involving traffic policemen and bank officers were carried out.