Measurements of ultrafine exhaust particles in Bratislava
Project manager: Dr. Kaare Press-Kristensen, senior advisor, air quality. The Danish Ecocouncil, Denmark. National partner: Dr. Daniel Lesinsky, campaign manager, clean air Slovakia Centre for Sustainable Alternatives: CEPTA, Slovakia.
Introduction Exhaust particles from diesel engines are mainly ultrafine particles (PM0.1) i.e. particles with a diameter less than 0.1 micro meter. These particles are measured in numbers of particles per cm3. Exhaust particles cause serious health problems in cities since the pollution increases the risk of heart diseases, airway diseases, cancer etc. A significant part of the ultrafine particles are soot particles (black carbon) contributing significantly to global warming as well. Exhaust particles can be efficiently removed by particulate filters.
Measurements Ultrafine particles were measured with a P-Trak (Model 8525 Ultrafine Particle Counter). One measurement was taken every second but minute averages were used in data treatment. Measurements were performed the following places in Bratislava in February 2013: 1) A public park outside the city. 2) A platform at the central train station. 3) A bus stop in the central city. 4) A platform in the central bus station. 5) Inside a gasoline/LPG car, cold start. 6) Inside a gasoline/LPG car in traffic. 7) In exhaust gas from gasoline and LPG.
Train station Figure 1 shows background measurements from the public park compared to the train station. The difference between electric and diesel locomotives are clear. Figure 1
Bus stop Figure 2 shows background measurements from the public park compared to the bus stop. People waiting at the bus stop inhale millions of harmful exhaust particles from traffic. Figure 2
Bus station Figure 3 shows background measurements from the public park compared to the bus station. People waiting at the bus station inhale millions of harmful exhaust particles from the busses. Figure 3
Table 1 shows average pollution levels. Table 1:
Particles/cm3 in average
Public park 10.760
Train station 21.975
Bus stop 57.670
Bus station 69.965
Gasoline/LPG car Figure 4a shows a 15 years old gasoline/LPG car started just below freezing point (cold start) with ventilation on max. It took three minutes to get out of the parking lot between two other cars. Hence, the car was filled with its own exhaust particles. It took several minutes before the particles were ventilated out of the car. Figure 4b shows air quality inside the same car driving in Bratislava. The concentration of ultrafine exhaust particles quickly increases when driving just behind a delivery van (diesel) and it takes minutes to ventilate out the pollution. Figure 4a
Behind delivery van Ventilator on
When switching the gasoline/LPG car from gasoline to LPG no particles were measured in the exhaust gas. LPG thereby eliminates the particle pollution.
Conclusion People in central Bratislava are heavily exposed to ultrafine exhaust particles when waiting at bus stops close to larger streets or at platforms in the central bus station. The same is the case for both car drivers and pedestrians using larger streets in the city. The main reason for the high pollution levels are old vehicles combined with a relative high share of diesel vehicles. One key solution is to establish a low emission zone with filter requirements for older busses and trucks and age requirements for light vehicles (< 3.5 tons) like the zone in Berlin. This should be combined with incentives to stimulate bicycle traffic and less car traffic. This would result in a much healthier population in this great city.
Funding This work was funded by the Soot free for the climate campaign and The European Commission, LIFE11 ENV/DE/495: Clean Air Europe. 3
Exhaust particles from diesel engines are mainly ultrafine particles (PM0.1) i.e. particles with a diameter less than 0.1 micro meter. These...