Air pollution impact on human health in the Sochi region
The problem of air pollution is tightly connected with the development of industry, transport and energetic. Continuous process of coal, natural gas and organic fuel burning aimed at obtaining electrical energy and heat, wide spread of automobile transport, waste of chemical plants and metallurgical works – all this leads to accumulation of different chemical compounds in the atmosphere, which affect the atmosphere composition in a planetary scale. Waste of nitric oxide, sulphur oxide and carbon oxide badly affect different components of biosphere. Health of the urban population in big industrial cities is aggravating because of air pollution. It has been found that air pollution results in building and monuments destruction. Among natural factors of air pollution there are volcanic activity and wind erosion, the latter is partially connected with agricultural development: extension of land under crops and soil destruction because of intensive exploitation.
Mathematical modelling of the air quality is getting more and more effective instrument in the analysis of atmosphere condition, due to the rapid development of electronic computers and decrease in their cost, and also perfection of mathematical models of transport of gaseous fluid- and solid dispersed components of pollution. Systems of free air quality modelling have been created in big cities such as Paris, Lisbon, Budapest, on a planetary scale, and over huge regions as Western Europe or northern latitudes of Eurasia, as well as in small towns such as Oxford or Cambridge, and even in the central street of London. We have investigated the air pollution impact on the human health in the Sochi region.
Sochi stretches for 146 km along the Black See coast. Only its narrow seaside strip of land, pressed by the main Caucasian mountain range against the Black Sea, is within the city boundaries. The wind rose, the breeze circulation, and the landscape make the air pollutants accumulate and precipitate locally in the Sochi region.
Sochi is a seaside climatic Russian resort, thus the air pollution can cause not only the extreme environmental situation in the city, but also the economical crises, because the residential districts as well as the resort institutions are located in the actively polluted zones, rather close to the motorway. This obviously affects the state of health of the Sochi residents.
The link between the air pollution and human health in the Sochi area has been established for several diseases as some form of cancer, and asthma. The significant correlation of 0.869 was found between the asthma sickness rate of children (asthma sick per thousand people in year) and the number of vehicles in the Sochi region - see Figure 1. The correlation of 0.8158 was found between the Sochi region residents and the number of vehicles - see Figure 2.
Figure 1. Link between the asthma sickness rate of children (asthma sick per thousand in year) and the number of vehicles in the Sochi region.
Figure 2. Link between the asthma sickness rate of residents (asthma sick per thousand in year) and the number of vehicles in the Sochi region.
Air pollutants turbulent transport in Central Sochi
The Central Sochi part shown in Figure 3 has been considered as applied example to estimate the air quality near the main streets. The computational square domain in the plane XZ intersects the main streets Kurortny Avenue and Ordgonikidze Street which are situated parallel to the Black Sea shoreline - see Figure 3. The atmospheric boundary layer flow predominate in the summer daytime is the breeze circulation. So, the wind direction is primary from the sea to the mountains, perpendicular to the street lines.
The database of the meteorological parameters in the Sochi region consists of the data set series for more then 100 years of the routine daily observations. The topography of the Sochi region includes the erosive relief and the rivers grid, the forest coverage, and the large difference of altitudes from the Black Sea level up to greatest altitude of 3256 m in the Caucasus Mountains. In the urban domain there are numerous buildings, that also it is necessary to take into consideration in the model of the air pollution transport in the lower part of atmosphere. As it has been established the main air pollution problem in this region is connected with the motor transport emission. Therefore the process of turbulent diffusion of traffic wastes is localised in the surface layer of atmosphere and greatly depends on parameters of turbulence as well as on the condition of stratification. Also the roughness of ground surface, including the artificial roughness in a form of buildings, trees, etc is a very important factor in this problem.
Figure 3. The computational domain chosen for an estimation of the air pollutants turbulent transport is parallel to XZ plain, and intersects the main streets in the wind direction.
The traffic flow and emission rate has been estimated for two main streets: Kurortny Avenue and Ordgonikidze Street. In summer daytime the traffic flow rate is about 1500 vehicles per hour for each of them in the cross section chosen for the air quality modelling.
It's known the carbon oxide and NOx the main air pollutants, which are dangerous for human. In the Central Sochi region the major souses of emission of CO and NOx are the gasoline passenger cars (>95%). The normal emission of CO is about 16 g/km in the urban region and about 30.4 g/km for the cold start. Hence the mean value of CO emission rate has been estimated as 19 g/km.
Put is the CO emission rate for one car, is the traffic flow rate (=the number of cars going on the road cross section in the unit of time). Then the total emission rate can be estimated as .
Figure 4. The isolines of CO concentration normalized on MPC in the turbulent stable (right) and unstable (left) stratified flow over the region with two parallel roads. Zones of the CO concentration over MPC are darkened
Thus in the considered case the CO total emission rate is about . This value has been used to compute the local zone in which the CO concentration is higher then the maximum permissible concentration.
The state sanitary standard adopted in Russia is the maximum permissible concentration (MPC) that in the case of CO emission is defined as CMPC=5 mg/m3.
The isolines of CO concentration normalized on MPC are shown in Figure 4 for the stable (right) and unstable (left) stratification. The heat flux is computed for the cloudless sunset time. The roughness length is estimated for the urban landscape as r=1 m. Figure 4 shows that the dangerous zones of CO concentration can be near the roads (about 20 m from the roadside) due to the small value of the turbulent intensity in the evening time.
The turbulent transport of NO and NO2 has been calculated for the daytime and evening time - see Figure 5. In this case the normal gasoline car emission rate is about 2 g/km, and for the passenger diesel it can
Figure 5. The isolines of NOx concentration normalized on MPC in the turbulent unstable (right) and stable (left) stratified flow over the region with two parallel roads located as shown by the black pointers. Zones of NOx concentration over MPC are darkened. In the black zones the NOx concentration in two times higher then MPC
be up to 12 g/km. Using the gasoline car emission rate the total emission rate of nitrogen oxides for the Kurortny Avenue can be estimated as .
The maximum permissible concentrations for the nitrogen oxides is much less then for the carbon monoxide, it's only CMPC =0.04 mg/m3 for NO2 , and CMPC = 0.06 mg/m3 for NO.
The turbulent transport data of NOx concentration normalized on MPC computed for the day time (left) and evening time (right) are shown in Figure 5.8. This data shows that the dangerous zones in the evening time occupy the region which has the width about 300 m, and the height up to 6 m. Therefore the dangerous zones of NOx concentration can occupy the habitable buildings as well as the kindergarten and musical school built near the considered roads cross section. Thus the nitrogen oxides can be one of the human health damaging factors in Sochi.
Turbulent transport of lead aerosols in Central Sochi
The lead aerosol is the most important damaging factor of the human health. The leaded gasoline has been widely used in the Sochi region. The lead concentration in the fuel dependent on the gasoline type varies from 170 up to 370 mg/l. The mean lead emission is estimated as mg/km. For the mean vehicle way per year about 30000 km it gives approximately 1 kg of the lead aerosol emitted by one normal passenger car.
The number of vehicles in the Sochi region has extremely grown in the last decade: from about 20000 in 1990 up to 100000 in 1999. The lead aerosol emission averaged on 10 years interval is 60 ton/ year. The total emission rate of lead aerosols for the Kurortny Avenue and Ordgonikidze Street in the modeled cross section is estimated as mgs-1m-2.
As it has been established in the numerical experiments the turbulent diffusion parameters of the particles with diameter less then micron, , practically independent on their diameter. The differences in the turbulent diffusion parameters are essential for the lead aerosol particles with diameter . The heavy particles, which have the diameter in the range, are deposited inside of the 200 m zone.
In the Sochi region in the end of 80's the concentration of lead was higher then the MPC of lead in the air and in soil near the main motorways. In the middle of 90's the environmental situation even more deteriorated in connection with significant increasing of the air pollutants emission. It has been established that the rise of air pollutants emission leads simultaneously to increase the sickness rate of respiratory diseases - see Figures 1,2. Therefore the local administration has forbidden using the leaded fuel in the Sochi region in 1996. In practice, however, the administrative measures on limitation of the air pollutants emission are not extremely effective, because the total control of exhaust gases is practically impossible to use.
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