Applying the waste hierarchy: guidance

Guidance on applying a waste hierarchy under Section 34 of the Environmental Protection Act 1990.

Annex 1: Overview of the environmental indicators

How was the Waste Hierarchy developed?

The position of individual Member States may vary with regard to the preferences given to particular management options when applying the waste hierarchy; for example due to variation in the technology and efficiency of electricity production (depending on the mix of fuels used and the efficiency of production); extent of landfill gas capture, and nature of the avoided materials.

This guidance sets out the Scottish Government’s position with respect to an order of preference for waste management options, based on the requirement to apply the waste hierarchy. The position set out is based on the environmental impacts associated with specific options whilst taking into account the current technology and infrastructure, proposed developments in the waste, recycling and resource management sectors as well as a national ambition to be a European leader. The selection of particular options for preventing or managing wastes are based on current best evidence from across the United Kingdom taking into account specific national considerations.

With a few exceptions (e.g. aggregates), emissions from transport of recyclable materials (including collection from the kerbside) are a very small fraction of the total environmental impacts, and they are dwarfed by the benefits of recycling. Where possible, the review of evidence on relative impacts of different options within the waste hierarchy has been made based on life cycle analyses (as well as other studies) that take transport emissions into account in overall impact assessment.

The ranking of the various waste management options are based on current scientific research on how the options impact on the environment in terms of climate change, air quality, water quality and resource depletion.

Selected environmental indicators

In accordance with methodologies used by government to help in making decisions on waste management options, we have selected four environmental impact indicators against which to compare waste management options based on the evidence that is currently available to assess the options on.

Climate change

Climate change, or global warming, refers to the increase in the average temperature of the Earth’s surface. This is caused by emissions of greenhouse gases including carbon dioxide, nitrous oxide and methane. Direct emissions from waste management contribute to all of these, and when emissions from the whole life of materials and products are included, the contribution of waste management, including prevention, becomes significant.

In Scotland, the Climate Change (Scotland) Act 2009 is the primary piece of legislation to drive reductions in greenhouse gas emissions and a transitioning to a low carbon economy. The Act sets in statue the target to reduce Scotland’s emissions of greenhouse gases by 80% by 2050 as well as an interim target of 42% reductions by 2020. The Climate Change (Annual Targets) (Scotland) Order 2010 sets annual total greenhouse gas emission targets for the years 2010-2022 with the Climate Change (Annual Targets) (Scotland) Order 2011 setting targets for the years 2023-2027.

Air quality (incl. acidification, ozone creation, toxicity (human and aquatic))

Acidification, primarily as a result of emissions of nitrogen and sulphur oxides, has direct and indirect damaging effects, such as nutrients being washed out of soils, increased solubility of metals into soils, aquatic habitat degradation, vegetation health impacts and damage to stone buildings as well as many other effects. Modern pollution control measures and tighter regulation of industrial emissions has reduced these emissions substantially but waste management options that have the greatest impact on further reducing these emissions should be prioritised.

Photochemical Ozone Creation Potential (also known as summer smog) is implicated in impacts such as crop damage and increased incidence of asthma. Emissions of pollutants as a result of waste management, incineration and disposal can react with strong ultraviolet light creating temporary smog in areas of high population and industrial density.

The management of waste can contribute towards increased pollutant emissions that may have a direct or indirect negative human health effect. Emissions of nitrogen oxides and hydrocarbons can lead to summer smog and exposure to elevated concentrations of particulate matter (very fine atmospheric dust particles in the range 2.5 to 10 microns) can have a long-term negative impact on human respiratory health. Options that ensure emissions of these pollutants are as low as practical should be favoured according to the hierarchy.

Water quality (incl. eutrophication)

The quality of water and its ability to support a diverse range of life is based on the balance of constituent components within the water ( inter alia dissolved oxygen, dissolved and particulate carbon, chemicals and nutrients) as well as the range of plants and animals it supports. The addition of toxic chemicals, organic pollutants and other contamination, produced as a result of management of waste materials, can cause disruption and damage to aquatic ecosystems such as estuaries, rivers, streams, ponds, lakes and reservoirs.

Eutrophication is when nutrient levels in freshwater bodies are elevated, often as a result of pollution or excessive applications of fertiliser to land or water, to a point where the delicate biological balance of aquatic habitats is disrupted. Fuelled by rising nutrient levels in the water, excessive growth (and death) of plants and algae can lead to decreased oxygen levels in water, creating conditions which cannot support diverse life. Certain areas of the Scottish countryside are particularly sensitive to such effects and careful monitoring and management of the nutrient balances may be required to reduce negative impacts on water quality and aquatic biodiversity.

Resource depletion

Resource depletion is the decreasing availability of natural resources including rare, precious and commodity products such as oil, metals, cereals and aggregates, some of which are renewable (e.g. wood) and some non-renewable (metals). As populations and economies around the world grow, demand and competition for finite resources increases. Global demand, rising quality of life expectations and population increase will, at today’s consumption rate, place unacceptable strain on the planet’s resources [3] . This will have a range of environmental, social and economic impacts.

Alternative options within the waste hierarchy have the ability to reduce our demand for resources and extend the life of the resources we currently use.


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