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Billions assigned to the fight against air pollution
Monitoring and the environment - a difficult balance
Air pollution in the electronic media
Application of sewage sludge to farmland

Environmental impact of urban society

NERI’s work focuses on the transport, turnover and environmental effects of environmentally hazardous substances, as well as the dispersion and effects of air pollution.

Billions assigned to the fight against air pollution

In 1999, the EU Commission will put forward a draft Directive placing national limits on emissions of the most important air pollutants. The proposed Directive and agreements already in force will cost the EU countries around DKK 400 billion - per year. The final negotiations are expected to be completed during the course of 1999. NERI is serving as advisor to the Danish negotiators.

Air pollution does not recognize national boundaries, and efforts to combat air pollution have therefore to be international if they are to have an effect. In this respect, the work on limiting acidification is one of the major success stories within international environmental cooperation. Thus sulphur dioxide (SO2) emissions in the EU have fallen by 55% since 1980 and nitrogen oxide emissions (NOx) have been reduced by 13% since 1987. The reductions have been attained as a result of a close interplay between research, monitoring and policy development. NERI has played an active role in monitoring and research, and has participated in the international cooperation in a number of working groups under the UN-ECE.

The EU’s draft Directive is part of a new strategy to combat air pollution. The strategy aims to reduce acidification, eutrophication and the effects of ozone on crops, forests, lakes and natural ecosystems. The strategy also encompasses the effects of ozone on nature and man.

The area of forests, lakes and other natural eco-systems in the EU totals approx. 120 million hectares. Implementation of the measures adopted to date will reduce the total area of the EU threatened by acidification from 37 million hectares in 1990 to 7 million hectares in 2010. Correspondingly, the area threatened by eutrophication will be reduced from 67 to 50 million hectares. Adoption of the draft Directive will mean that the EU countries will have to invest billions of dollars to further curtail air pollution. Measures will be taken against acidification, the effects of ozone and eutrophication. Implementation of the Directive will entail protection of a further 2.4 million hectares against acidification and 8.3 million hectares against eutrophication. In comparison, the area of Denmark is 4.3 million -hectares.



Photo: Sonja Iskov



Urban Air Pollution is a newly published international book edited by NERI scientists Jes Fenger, Ole Hertel and Finn Palmgren. The book focuses on European conditions, and is mainly directed at university students and air pollution experts.

A decisive factor in the negotiations has been to ensure the greatest possible environmental benefit for the money. Among other means, this can be attained by a combined strategy against the three types of effect. NERI has helped ensure that data pertaining to Denmark is as correct as possible. Nevertheless, the cost to Denmark is great - an estimated DKK 3.9 billion per year up to the year 2010. The money will mainly be used to further reduce emissions from power stations, waste incineration and traffic.

In the coming years, NERI will continue to actively participate in the work with the EU Acidification Directive as well as a corresponding agreement for the whole of Europe under the auspices of the UN-ECE. In addition, NERI is involved in arranging an international conference "Critical Loads Copenhagen" to be held on 21-25 November 1999 under the auspices of the UN-ECE. The work on assessing the effects of air pollution in Denmark will be strengthened, among other things with a view to assessing the need for further regulation in Denmark. In 1998-99, NERI provided the scientific foundation for a Danish action plan to regulate ammonia emissions.


Anticipated reductions in air pollution (1,000 tonnes) up to the year 2010 as a result of the measures adopted to date and the proposed new EU Directive. For Denmark this will mean new limits on emissions.

Motoring and the environment - a difficult balance

Car traffic constitutes a steadily growing pressure on the environment. Our use of and attitude towards cars differs considerably, however. For some people the use of a car is a necessity, while for others it is a luxury. If our transport behaviour is to be changed, this will require changing both our lifestyle and our attitude to the environment.

Transport presently constitutes one of society’s greatest environmental problems - with motoring being the main contributor. There are significant differences between how much each individual moves, for what purpose and by what means. At one end of the scale the impassioned motorist, and at the other end the person who never touches a car. In some respects, the mutual differences are just as great as between Danes of today and those of the 1930s. For example, a person in a 2-car household is responsible for the emission of 5 times as much CO2 as a person without a car.

Behaviour, traffic and environmental consequences are parts of a complicated interplay that needs to be understood if one wants to solve the environmental problems of traffic: air pollution, noise and destruction of nature. The health of a large number of people is affected and many lives are lost as a result of both accidents and pollution, the loss from both causes being estimated to be roughly equivalent at present. To this must be added the negative impact of the deposition of nitrogen compounds on terrestrial and aquatic ecosystems. Moreover, the relative contribution of traffic to CO2 emissions is continually growing, thereby helping to enhance the greenhouse effect.

NERI’s report examines what demands will have to be imposed in the future to ensure environmentally sustainable development. A study by NERI has shown that there is a willingness among the majority of the population to help reduce car traffic. If society wants to increase the sustainability of transport it is not sufficient just to curtail car traffic. One also has to improve the possibilities for public transport and for cyclists. Finally, one has to acknowledge that it will be important to limit emissions from both public means of transport - busses, trains, aircraft and ferries - and from cars.

In the coming years, NERI will continue to develop a behavioural model in order to be able to regulate transport behaviour, and to develop the term sustainable transport. The work on trying to understand the significance of transport for the everyday life of the population will also be continued.

Photo: Sonja Iskov

Photo: Sonja Iskov

Air pollution in the electronic media

The severity of ozone pollution is now published on text-TV. At the same time, NERI is making an increasing amount of information on air pollution available on the Internet. During the course of 1999, moreover, the first air pollution forecasts will be added to NERI’s home-page.

Only a few years ago, studies of air pollution were rarely something one heard of until long after the measurements had been made. Today, though, the public demands rapid access to information. NERI has therefore turned to the electronic media to ensure rapid dissemination of information on air pollution.

Since June 1998 it has been possible to follow the nitrogen dioxide (NO2) and ozone (O3) content of the air on national text-TV. The data is updated every second hour during the daytime under normal conditions, and every hour during episodes of severe air pollution. This is part of the smog warning system. The system encompasses warnings for sulphur dioxide (SO2), nitrogen dioxide and ozone, although in practice the so-called warning threshold is only expected to be exceeded for ozone. The warning threshold for ozone is 180 microgrammes per m3, a level that is normally only exceeded in Denmark 1-2 times during the course of the summer.

NERI has hitherto used the national radio news to inform the public immediately after the incidents of threshold exceedence. As they always occur in the afternoon on very warm summer days, only very few listeners hear the information. NERI has therefore decided to disseminate the information on air pollution via national text-TV. Here one can follow the air concentration of ozone measured at Roskilde and on Langeland, and the content of nitrogen dioxide measured in Copenhagen, Odense and Aalborg.

Much other information on air pollution is available on NERI’s Internet homepage. The data are updated regularly. In addition, annual data are available showing the trend over a number of years. From this it can be seen that things are generally moving in the right direction. A good example is the sulphur dioxide content of the air, which has fallen over the past 15 years. During the same period, the lead content of the air has essentially declined to zero. During the course of 1999, NERI will expand the Internet homepage to also include 3-day ozone forecasts.

Map of the stations included in NERI’s air monitoring programme. One can retrieve information on their location and monitoring programme by clicking on the stations on NERI’s Internet homepage.

Application of sewage sludge to farmland

Nonylphenols and phthalates are two groups of substances widely found in industry, house-holds and the environment. The discovery that they have hormone-like effects has therefore aroused considerable concern. Among other things, attention has focused on their concentrations in sewage sludge because they are virtually non-degradable in wastewater treatment plants. A new study by NERI shows that only small amounts of these substances are discharged by industry and that they do not accumulate in agricultural soils treated with sewage sludge in moderate amounts.

The sources of phthalates and nonylphenols were investigated in the catchment area of Roskilde municipal wastewater treatment plant. The sewage contained a number of phthalates, of which DEHP (a plasticizer) occurred in the highest concentrations. The concentration in the inflow to the wastewater treatment plant lay within the level found in other corresponding studies. The concentration of DEHP in the sewage sludge averaged 25 mg/kg dry matter, which corresponds to the median value for 20 Danish wastewater treatment plants. The Danish EPA has set a limit level of 100 mg/kg dry matter, although this will be reduced to 50 mg/kg from the year 2000.

A total of 240 kg DEHP flowed into the treatment plant annually. Of this, only a minor part derived from the enterprises investigated: 7 kg from industrial laundries, 2 kg from car washes and 1 kg from a hospital. A further 3 kg derived from the air. The majority of the DEHP thus seems to derive from households, with the major sources possibly being clothes laundry and the cleaning of vinyl flooring.

Another part of the study examined the fate of the substances when they are applied to agricultural land via the application of sewage sludge. DEHP was also the dominant phthalate in the soil, nonylphenols rarely being found in high concentrations. The study showed that moderate application of sludge - 4 tonnes dry matter per hectare every third year - did not give rise to enhanced concentrations of phthalates and nonylphenols in the soil. With very intensive application - 17 tonnes dry matter per hectare per year - of sludge containing high concentrations of phthalates and nonyl-phenols, the substances accumulated in the soil. Possible explanations are that biological degradation could not keep pace with the input or that the substances bind to the soil such that they are not available for degradation.

From the year 2000 it will be permitted to apply 7 tonnes dry matter per hectare per year in Denmark. In by far the majority of cases, however, the high phosphorus content of the sludge will limit the dose to under 2 tonnes dry matter per hectare per year.

These studies have now been completed and the results presented in NERI Technical Reports Nos. 225 and 249, as well as in an issue of NERI’s Danish language popular science series of theme reports. The project is being continued as a study of nonylphenols and phthalates in Roskilde Fjord. Selected samples from the project will also be analysed for a number of other environmentally hazardous substances.

NERI has also conducted laboratory studies of the effects of DEHP and other environmentally hazardous substances, especially on the soil fauna. A few of the substances have effects at low concentrations. These effects cannot be seen in field experiments, however, probably because of binding and degradation. Over a period of three years, no negative effects have been detected in research plots, even at high levels of sludge application, growth of the soil faunal communities being comparable to that in fields fertilized with livestock manure.

Vertical distribution of various nonylphenols and phthalates in agricultural soils fertilized with large amounts of sewage sludge (17 tonnes dry matter per hectare per year).

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