Analysis of inhalatory exposure to air pollution is an important area of investigation when assessing the risks of air pollution for human health. Inhalatory exposure research focuses on the exposure of humans to air pollutants and the entry of these pollutants into the human respiratory tract. The principal grounds for studying the inhalatory exposure of humans to air pollutants are formed by the need for realistic exposure/dose estimates to evaluate the health effects of these pollutants. The AirPEx (Air Pollution Exposure) model, developed to assess the time- and space-dependence of inhalatory exposure of humans to air pollution, has been implemented for use as a Windows 3.1 computer program. The program is suited to estimating various exposure and dose quantities for individuals, as well as for populations and subpopulations. This report describes the fundamentals of the AirPEx model and provides a user manual for the computer program. Several examples included in the report illustrate the possibilities of the AirPEx model in exposure assessment. The model will be used at the National Institute of Public Health and the Environment as a tool in analysing the current exposure of the Dutch population to air pollutants.

The technical background to supporting the policy decisions on allocating phosphate-saturated soils and tackling the problems which these soils cause are presented here. Since 1987 the Dutch government has taken several steps to diminishing the problem of phosphate-saturated soils.New legislation will become available in 1998 for regulating the use of nutrients. The Ministries of Agriculture, Nature Management and Fisheries (LNV) and of Housing, Spatial Planning and the Environment (VROM) are planning to issue a general administrative order (GAO) to regulate phosphate use on phosphate-saturated soils. Several choices have to be made beforehand (1) Should the GAO cover the total agricultural area or should it be limited to, for example, the areas with known high historical loads? (2) What method should be used to identify phosphate-saturated soils? (3) Should management of all phosphate-saturated soils be restricted by the GAO or only the most polluted ones? (4) What level of net phosphorus export from the fields for which the GAO prescribes management restrictions should be implemented? Alternative answers to each of these questions have been formulated, with the pro's and cons for each given. Answers from the perspective of the GAO regulating farm management pertain to the national scale. The alternatives described can also be used for regulation limited to selected areas, such as those for nature conservation. In this case, methods described here can be used to select fields within the selected areas. In conclusion, several suggestions for future research are given, such as focusing on the effects in the long and medium term of soil phosphorus depletion on both agriculture and the environment. Although there are still questions to be answered, it has been made clear that the phosphorus status of most soils in the Netherlands at the moment is unnecessarily high from both the agricultural (plant production) and the environmental viewpoints.

The Natureplanner is essentially a computer system to predict the effects of environmental and spatial scenarios on nature for national and regional policy. It supports further the decisions on setting environmental standards, on detection of the dominant stress factor and the choice between area specific or general or mitigation measures and the costs. The smallest spatial resolution is 250*250 m. The dominant stress factor will be the most cost effective target for policy making; in some areas this will be desiccation and in others it may be eutrophication caused by deposition of NH3 from agriculture. The system has functions for viewing databases and maps of species distribution, soil or environmental scenario's. It is possible to choose a new vegetation structure in certain grid cells and than to compute the probability of occurrence of species under the given environmental conditions of soil, groundwater and acid or N-deposition. Another important application of the Nature Planner on a more regional scale is the computation of the specific critical N-load for a nature reserve. Further development is going on in close co-operation with other research institutes and some provinces with respect to: aquatic ecosystems, ecotoxicological aspects, succession/management practices, salinity, climate, and a separate module for effects of environmental changes and landscape fragmentation on birds and other fauna.

This model study assessed the environmental effects of several technical measures for the reduction of energy and water use and the use of materials in existing and new dwellings, projected over the 1995-2020 period. The model assesses the effects by a physical causal represention of the dwellings. The measurements taken alter the energy, water and materials efficiency in the dwellings, leading to a reduction in the use of each of the three resources. Taking place under the policy of sustainable building the above measures are instrumented by regulation (energy efficiency in newly built dwellings), information transfer and covenants with the public and private partners in the decisionmaking chain of the building industry. Each of the measures has been equiped with an penetration scenario for the autonomous developement and the stimulus for this given by the sustainable building policy. The set of relevant policy instruments imposed by the sustainable building policy will be either certainly or probably employed up to 2005. The instruments are assumed to persist after this period, thus leading to a continued penetration of the measures.

The aim of the study reported was to establish a basis for a realistic comparison of energy- efficiency to emissions from the different passenger and freight transport modes. Besides this report will also focus on of a modal shift on the effects on energy use and emissions. The energy use and emissions applied in the calculations arose from the production of fuels and electricity and yielded the following main conclusions: (1) Passenger transport by electric trains shows the lowest emission factors in 1995 compared to the other passenger transport modes. The city bus shows slightly higher energy efficiency than the passenger car used for city trips. The emissions of NOx and particles from the city bus are three times as high as those from the passenger car. The touring bus has the highest energy efficiency, followed by electric rail transport. (2) As mentioned above, a comparison of energy use with emissions per passenger kilometre using different passenger transport modes does not say anything about the effect on energy use and emissions of a modal shift from passenger cars towards public transport. Every increase in city-bus use at the cost of passenger-car use leads, at the current occupation rates, to avoiding an emission and energy use as large as the emission and energy use of one passenger car. (3) As a result of a further tightening of emission standards for road traffic combined with the delay of emission standards for diesel passenger trains, the environmental lead of electric passenger transport is declining. (4) With the current differences in type of transported goods, freight transport by road vehicles is 2 to 2.5 times less energy efficient than inland shipping or rail transport. However, the same can be concluded where transport of similar goods (containers) by the different modes is concerned. The emissions from electric rail transport are much lower than those from inland shipping or road transport. (5) In view of the coming tightening of the emission standards for road vehicles, combined with the delay of emission standards for freight trains (with diesel engines) and inland ships, there will be a much smaller gap between road and rail-freight transport in 2010.

This report documents how future health risks related to an increase in the use of surface water for the production of drinking water have been examined. For a number of pesticides, heavy metals, micro-organisms and disinfection by-products, possible future health risks are determined using the logical approach from the emission of these substances and micro-organisms in the environment up to and including the concentration in drinking water. To gain some insight into the effect of the drinking-water production on (future) drinking-water quality several purification methods were calculated. It may be concluded that the quality of the surface water used for the production of drinking water will improve slightly up to 2020 for pesticides, while for the heavy metals and mic-organisms, hardly any change will occur in the surface-water quality in the same period. Substances (pesticides and heavy metals) barely form a threat to the drinking-water quality. Removal of micro-organisms requires extensive purification, with soil infiltration (with closed extraction) being the most preferable method in the purification scheme. Technical solutions such as membrane filtration and possibly chemical disinfection can also be used. Toxic disinfection by-products exceed the maximum risk levels many times over. This report gives a shapshot view of the aspects on quality of several purification methods according to the 'worst-case' scenario and indicates. The report gives notice of what factors (substances/micro-organisms and purification steps) related to the development of the unclean water quality, considering development of the unclean water quality, might be important in the future.

Regional waters are being dredged once every 5 to 20 years to maintain the water discharge. The dredged material must meet certain objectives if it is to be disposed of in the adjacent soil. However, PAH levels exceed the sediment target value of 1.0 mg sum of PAH per kg dryweight of sediment in 60% of the ditches. In a preceeding study the present and future sediment quality has been investigated. In this study a probabilistic model was developed to investigate the effect of repeatedly distributing sediments on different categories of soil. When PAH concentration in sediment exceeds the target value up to a level of 10 mg.kg-1 (standard above which sediments must be deposited into a depot), only farm-land on sandy soils will show no exceedance of the target value for soils (equal to the target value for sediments). The other categories, farm-land on clay, grass-land on clay and grass-land on peat, show a considerable chance of exceedance of the target value. However, when being distributed, many of the sediments in which levels of PAH above the target value were measured, will cause no exceedance of the soil target value. For sand, clay and peat ditches respectively 100%, 63% and 74% of all measurements will lead to soil concentrations below the target value when being deposited on a regular basis. Decreasing atmospheric deposition will enlarge the possibility of distributing sediments without exceeding target values, especially in the case of farm-land on clay.

Volatile Organic Compounds (VOC) have been measured in the Dutch National Air Quality Monitoring Network since 1993. An evaluation of the measurement strategy has been executed, which showed that the network configuration and the time resolution of measurements was found no longer fullfilling the information requirements with respect to policy support and development. The basic principles for the redefinition of the measurement strategy for VOC were: a) meeting the measurement obligation for benzene and corresponding requirements (the OPS and the CAR model being the most important) and b) supporting the 'Carbohydrates-2000' project. For the measurement configuration , three regional sites have been chosen according to the principle 'north-middle-south'. The definition allows for influences of sources in Germany and Belgium, and in the Rijnmond area, and influences from large-scale background levels. Four street stations along with one city background station, will be used to describe air quality in cities. One supplementary site has been defined within the Rijnmond area. A spatially coherent set of stations (i.e. 'regional-city background-street') has been selected within this configuration. The time resolution of the sampling will be one day (for the spatially coherent set of stations and the site in the Rijnmond area) or one week (other stations). The OPS model which calculates monthly to yearly average VOC concentrations on a national grid with a spatial resolution of 5x5 km, will require for validation purposes, results from regional, and to a limited degree, city stations. The CAR model, which calculates yearly average concentrations of traffic-related components, will use results from city background and street stations. The 'Carbodydartes-2000' project will be supported by the measurement site in the Rijnmond area and, to a lesser degree, by the regional sites in the middle and northern part of the country.

Bottom-up data for carbon dioxide, methane and nitrous oxide from the official national inventories (National Communications) were compared with data from EDGAR (Emission Database for Global Atmospheric Research) and top-down emission estimates, based on the results of dispersion and climate models using measured concentrations of greenhouse gases in the atmosphere. The aims of this preliminary study were to investigate the possibilities of comparing different types of emission inventories, to develop a methodology for this comparison and to use the results in an analysis to identify areas for improving the IPCC methodology. The main conclusion points to the value of an international program to review and evaluate national inventories of greenhouse gases. Both bottom-up and top-down emission data were found to improve the scientific understanding of the global and regional budgets. Data exchange promotes consensus on the data among scientists and policy-makers. For CO2 , it is not possible at the moment to estimate fossil fuel emissions derived from atmospheric measurements and global carbon dioxide budget calculations with more accuracy than for emissions based on bottom-up emission inventories. For CH4, a global or even a zonal comparison of bottom-up emission inventories with top-down results of transport models is possible; furthermore, uncertainty for specific sources may have been reduced. Uncertainties for N2O emissions are so large that we may expect both top-down and bottom-up emission estimates to benefit from results of a careful comparison of these emission estimates. Comparing national inventories with EDGAR data has identified areas for future improvement in the IPCC Guidelines.

This inventory of greenhouse gas emissions in the Netherlands has been prepared according to the IPCC Guidelines and complies with the obligations under the European Union's Greenhouse Gas Monitoring Mechanism and the UN-FCCC for emission reports on greenhouse gases not covered under the Montreal protocol. The temperature corrected total emissions of non-ODP greenhouse gases were found to increase by 7% from 1990 to 1996, mainly due to increasing emissions of CO2. In 1996, the temperature-corrected carbon dioxide emissions were 7.6% higher than in 1990. In the period 1990-1996, methane emissions decreased by 9%, but nitrous oxide emissions increased by 13%. The emissions of HFCs were 47% higher in 1996 than in 1990, while the CO2-equivalent emissions of HFCs, PFCs, and (potential) SF6 increased by 26%. In 1996, CO2 contributed 75% to all CO2-equivalent emissions in the Netherlands, CH4 contributed about 11%, N2O about 9% and the non-ODP halocarbons about 5%. A short description is given on how the Guidelines have been applied in the Netherlands. Differences between IPCC sectors and Target Groups in the Netherlands are addressed and resulting emission differences accounted for.