Physicians bear Arnika out. “We can now talk about a time frame. We will be facing health problems among a major part of the population in a few decades as a consequence of air pollution. Today’s newborns could suffer from an increased incidence of cardiovascular diseases in middle age; air pollution will be reflected in an increased rate of respiratory illnesses, and disruption of children’s immune systems,” says Radim Šrám, M.D. from the Institute of Experimental Medicine of the Czech Academy of Sciences. Doctor Šrám monitored the impact of polluted air on the health of policemen and bus drivers in Prague. “We proved, among other things, genetic damage. Not solving the problems now could result in substantial economic costs related to illness rates in the future,” the Doctor warned (6).
The assumption that air pollution can to a certain extent be compensated by greenery has been proven by a number of expert studies. In early October the Czech Academy‘s Environment Commission (7) adopted a statement on this matter. “Greenery’s plays a very significant role in the health status of the population, especially children, and in the quality of the environment in urban agglomerations. The idea that every vacant area should be used for residential, commercial or other construction is absolutely erroneous and unacceptable.”
Concerns have been raised especially by the new zoning plan being prepared right now. “The zoning plan will predestine the city’s development for another decade. Its basic idea is to transfer the majority of arable land and a part of the green areas into the category of building parcels. So far, no-one has said what impact this massive construction will have on life in the city. For example, new buildings always cause an increase in traffic,” said Martin Skalský of Arnika.
“City Hall points to the planned green belt around the city and a statistical increase in green areas; however, it is a misleading argument. The statistics are not accurate and a detailed stocktake of green areas does not exist. Moreover, greenery on the outskirts has quite a different function than it has in the city centre’s densely built-up areas,” Skalský added.
The problem of the decrease in greenery has been also pointed out by the Czech Environmental Inspectorate. ”Trees in cities have a number of indispensable functions. They create oxygen, alleviate heat in streets, dampen air, absorb dust and microorganisms and reduce noise,” explains Ing Tomáš Mařík, head of the Department for Nature Protection. “We very rarely realize to what extent greenery improves the quality of our environment,” he adds.
Václav Větvička, a doctor of natural sciences, who was for many years the director of the Prague Botanical Garden, explains the reasons why he became a member of the new petition committee. “It is not only the issue of tree felling but of interventions in city greenery in general. Today the role of the public is underestimated, individual interventions are never explained and that is a shame. The zoning plan should also take into account the proportions between built-up and green areas. If some greenery is liquidated it should be adequately replaced – in the same place and to the same extent. The overall area of greenery should not diminish.”
Arnika will collect signatures at petition stalls in Prague streets. People can also sign the petition at their website: http://arnika.org/petice. The association will hand over the petition to the City Hall and municipal districts and will demand that Prague trees be better protected and green areas preserved.
(1) Stationary source emissions in Prague have been decreasing in the long term. (Emissions of solid substances, sulphur dioxide and nitrogen dioxide are monitored.) This favourable development is a consequence of reducing fuel consumption (through an increase in the use of heat from the Mělník-Prague heating plant, savings by heat energy users, the reduction of industrial production output after 1990 etc.), due to the change in the structure of fuels burnt (replacement of solid fuels with gas), and efficient heating plant operation (reconstruction and updating). Another significant cause is the pressure of economic and legislative measures aimed at reducing emissions from these sources.
The largest source of air pollution today is represented by motor vehicle traffic. Dust microparticles of PM10 (size 10 microns), sulphur dioxide, nitrogen dioxide, carbon monoxide and carbon hydrates, volatile organic substances and benzene are monitored. Dust microparticles are the most dangerous because they bind with a number of toxic substances. Even though traffic is also a source of PM2.5 micro dust particles, their levels are not monitored in Prague. However, the applicable rule is that the smaller the dust particles are, the more dangerous they are. Particles smaller than 2.5 microns enter the blood circulatory system directly via the lungs. Some dust particles are directly produced by fuel combustion in motor vehicle engines; some are the so-called “secondary dust” which is swirled around by the vehicle’s movement. As far as nitrogen dioxide and PM10 dust particles are concerned, the largest polluters are heavy trucks. In respect of other indicators the majority of air pollution is caused by passenger cars.
- Prague Environmental Yearbooks
- Atlas of Prague’s Environment
- Information System on the Environment in Prague
(2) According to expert studies, vegetation in cities has a number of indispensable functions. Trees reduce summer heat, increase air humidity, produce oxygen and absorb carbon dioxide, provide shade, absorb dust and hazardous microorganisms and support air circulation. Trees have also been proven to have an impact on heat savings in buildings; in summer, due to decreasing the need for cooling it is 30%, in winter, trees protect buildings from cold winds, saving 20 - 50% on heating costs. Last but not least, trees also have an aesthetical function and provide habitats for animals.
A tree transpires 50 to 80 litres of water per day – those with a crown spanning 9 metres can transpire as much as 151 litres of water a day. Due to the shade the crown provides, the temperature under it is 6 degrees Centigrade lower than that in its surroundings.
Monitoring in 21 European cities has established the impact of PM10 dust particles on human health in cities with higher temperatures. It has been proven that mortality increases with higher temperatures, a heavy construction densities and high volumes of traffic. In Portugal, under an extreme combination of unfavourable conditions, the death rate increased by 49.8%, in the Czech Republic by more than 10% and in Paris by as much as 142%. Therefore the World Health Organization recommends an approach to urban planning that will enable the creation of “cool spots” i. e. green areas.
Studies conducted in the USA combined meteorological and air pollution data. The computer model created demonstrates what amount of pollutants in the atmosphere of American cities can be absorbed by trees. Ground-level ozone, PM2.5 and PM10 particles, carbon dioxide, carbon monoxide and nitrogen dioxide were monitored. It has been found that over one year, the trees absorbed 711,000 tons of these hazardous substances and thus the value of their services amounted to 3.8 billion dollars.
Other studies conducted in Great Britain have proven that tree planting in urban areas can reduce air pollution by as much as 25%. If for example in the West Midlands region the total tree cover increased from the current 3.7% to 16.5%, PM10 concentration levels would drop by 19%. Increasing tree cover of the West midlands to a theoretical maximum of 54% (achievable only by planting all available green space) could result in a 26% decrease in PM10 concentrations, removing 200 tons of primary PM10 per year. This would mean that every year the atmosphere would contain 200 tons of dust particles less. The study estimates that every year in Glasgow trees trap 4.99 tons of PM10 particles from the air. Today in the West Midlands trees absorb 7% of the dust particles produced by human activity, which represents 39.63 tons of PM10 particles removed from the atmosphere every year. If we planted trees in a quarter of the vacant areas in our cities average concentrations of hazardous dust would drop by 2 to 10%.
- Eva Rychlíková, M.D., ČIŽP (Czech Environmental Inspectorate) Prague, 2008, presentation for the Environmental Commission of the Czech Academy of Sciences. Sources quoted in the presentation: McPherson et al. 1994, Nowak et al.
- Quantifying the effect of urban tree planting Impacts on concentrations and depositions of PM10 in two UK conurbations, by A. G. McDonald et al. (2007). Details and the whole study are available here.
(3) A serious problem in recent years is related to changes in Prague’s zoning plan. The procedure is always analogous: the developer buys a vacant plot which is classified in the zoning plan either as “greenery” or “other” and has it changed into a building parcel. Then it is practically impossible to prevent construction on the plot. This is precisely what happened on Balabenka, where the park was replaced by a Skanska office building. In the buffer zone of the Košíře-Motol natural park, several housing developments went up – the first was Cibulka Housing where the developer (Metrostav) illegally felled more than 200 trees. In Vokovice the approved change in the zoning plan has enabled construction on green areas of the former Strnad Market Garden, which might destroy the Dejvice brook.
The existing trend can be further aggravated by the new zoning plan. According to available information, the City Hall intends to change vast areas of farming land and “other” plots into building parcels. This also threatens some green spaces – e. g. construction is planned in the Dívčí Hrady location, on Kavčí Hory and elsewhere. Moreover, massive construction will bring about a substantial increase in traffic, which Prague is not ready to tackle and which will lead to further deterioration of air quality.
(4) The Petition for the Protection of Prague’s Trees and Green Spaces is also available on the Internet and you can join it.
(5) A stocktake of Prague’s greenery was last carried out and published in 1995. The document contains data on the amount of greenery in respective cadastral districts. Greenery is then divided into several categories and this enables people to follow not only the changing figures but also the qualitative indicators. Stock-taking also divides greenery into plants, bushes and trees, provides data on the status of the monitored greenery, its accessibility for the public and so on.
At present the only overview of Prague greenery is provided by the Environmental Yearbook but it is much less detailed, being based on the cadastre of real estate data. This can be rather inaccurate – the real condition of lands and their identification in the cadastre can vary. The Yearbook’s statistics imply that farming land in Prague has diminished over the long term and the proportion of built-up areas has increased at its expense. However, the Yearbook does not take into account a number of spaces with lower-quality greenery, which have also been disappearing. In the overall area of Prague, 35%, i. e. more than a third, is comprised of the so-called “other” plots, with building-sites, brownfields and also a number of green spaces. The decrease in this type of greenery is not monitored.
The Prague system has another snag – City Hall does not keep track of all greenery. A significant proportion of all greenery is in the ownership of municipal districts or in the hands of private owners. These plots are not recorded in City Hall’s Yearbook.
(6) Dr Radim Šrám’s research team examined the impact of polluted air on human health. They monitored policemen and public transit bus drivers to that end, but further, they conducted analyses of children’s health status. The research focused on PM10 and PM2.5 microparticles and benzo(a)pyrene and concluded that the level of air pollution is directly connected with the growth of illness rates in children, especially as far as immunodeficiency and respiratory diseases are concerned. With adults, oxide damage caused by harmful substances in the atmosphere can give rise to cancer, atherosclerosis and diabetes, and also accelerates the aging process. In their conclusions the researchers recommended an increase in the amount of green spaces, because of their ability to absorb fine dust particles – and provide places for relaxation. Therefore the number of new parks being laid out and new trees planted should be increased.
(7) The Standpoint of the Environmental Commission of the Czech Academy of Sciences on the significance of green spaces for human health (of 8 October 2008) is available here.