4. Screening

This Section introduces the different procedures and methods for identifying

whether or not an EIA is required for a proposal. It examines their relative

strengths and weaknesses, and allows participants to gain initial familiarity

with the concept of impact ‘significance’ and its importance in triggering the

right level of EIA review.

Learning Outcomes of this Section

On successful completion of this Section, you will be able to:

  • Understand and explain why screening is necessary in EIA
  • Know how to undertake screening, including knowledge of procedures and project lists
  • Be able to articulate the criteria determining the need for EIA

Screening is the first key decision  of the EIA process. Some type of screening

procedure is necessary because of the large number of projects and activities

that are potentially subject to EIA. The purpose of screening is to determine whether a

proposal requires an EIA or not. It is intended to

ensure that the form or level of any EIA review is commensurate with the

importance of the issues raised by a proposal.

The conduct of screening thus involves making a preliminary determination

of the expected impact of a proposal on the environment and of its relative

significance. A certain level of basic information about the proposal and its

location is required for this purpose. The time taken to complete the screening

process will depend upon the type of proposal, the environmental setting and

the degree of experience or understanding of its potential effects. Most

proposals can be screened very quickly (in an hour or less) but some will take

longer and a few will require an extended screening or initial assessment.

Similarly, the majority of proposals may have few or no impacts and will be

screened out of the EIA process. A smaller number of proposals will require

further assessment. Only a limited number of proposals, usually major

projects, will warrant a full EIA because they are known or considered to have

potentially significant adverse impacts on the environment; for example, on

human health and safety, rare or endangered species, protected areas, fragile

or valued ecosystems, biological diversity, air and water quality, or the

lifestyle and livelihood of local communities.

The screening process can have one of four outcomes:

  • no further level of EIA is required;
  • a full and comprehensive EIA is required;
  • a more limited EIA is required (often called preliminary or initial assessment); or
  • further study is necessary to determine the level of EIA required (often called an initial environmental evaluation or examination [IEE]).

Screening establishes the basis for scoping, which identifies the key impacts to

be studied and establishes terms of reference for an EIA. Many EIA systems

have formal screening and scoping procedures. In some cases, however, these

terms may be used differently or applied at the discretion of the proponent. Also, on occasion, the screening

and scoping stages may overlap, for example, when a further study (or IEE) is

undertaken to determine whether or not the potential impacts are significant

enough to warrant a full EIA.

The requirements for screening and the procedure to be followed are often

defined in the applicable EIA law or regulations. In many cases, the proposals

to which EIA applies are listed in an annex. Usually, the proponent is

responsible for carrying out screening, although this is done by the competent

authority in some EIA systems. Whatever the requirements, screening should

occur as early as possible in the development of the proposal so that the

proponent and other participants are aware of the EIA obligations. It should

be applied systematically and consistently (so that the same decisions would

be reached if others conducted the screening process).


The screening procedures employed for this purpose can be classified into two

broad, overlapping approaches:

  • prescriptive or standardised approach – proposals subject to or exempt from EIA are defined or listed in legislation and regulations; and
  • discretionary or customised approach – proposals are screened on an individual or case-by-case base, using indicative guidance.

Specific methods used in screening include:

  • legal (or policy) definition of proposals to which EIA does or does not apply;
  • inclusion list of projects (with or without thresholds) for which an EIA is automatically required; exclusion list of activities which do not require EIA because they are insignificant or are exempt by law (e.g. national security or emergency activities); and
  • criteria for case-by-case screening of proposals to identify those requiring an EIA because of their potentially significant environmental effects.

Both prescriptive and discretionary approaches have a place and their

specific procedures can be combined into a comprehensive procedure (as

shown in Figure 1). Where inclusive project lists are used, the disposition of

most proposals will be immediately apparent. However, some proposals will

be on the borderline in relation to a listed threshold and for others, the

environmental impacts may be unclear or uncertain. In these situations, caseby-

case screening should be undertaken, applying any indicative guidelines

and criteria established for this purpose. This process gives the proponent or

competent authority greater discretion than mandatory lists in determining

the requirement for EIA.

Figure 1: A framework for screening (image on page 193)

In this context, screening is a flexible process and can be extended into

preliminary forms of EIA study. These ‘extended screening’ procedures


  • initial environmental examination – carried out in cases where the environmental impacts of a proposal are uncertain or unknown (e.g.
  • new technologies or undeveloped areas);
  • environmental overview – carried out as a rapid assessment of the environmental issues and impacts of a proposal; and
  • class screening – carried out for a family of small projects or repetitive activities, where the environmental effects and means of mitigation are known but there is potential for cumulative impacts (e.g. dredging, road realignment, bank stabilisation).

Project lists are widely used to screen proposals. These lists are of two types.

Most are ‘inclusion’ lists, which describe the project types and size thresholds

that are known or considered to have significant or serious environmental

impacts. Usually, listed projects that fall within these predetermined

thresholds will be subject automatically to full and comprehensive EIA. Some

EIA systems also maintain ‘exclusion’ lists of activities that are exempt

because they are known to have little or no environmental impact.

The inclusion lists used by countries and international organisations differ in

content, comprehensiveness, threshold levels and requirements for mandatory

application. In certain EIA systems, scale thresholds are specified for each

type of listed project for which an EIA is mandatory. Other projects that may

require an EIA are screened individually against environmental significance

criteria, such as emission levels or proximity to sensitive and protected areas.

Internationally, reference is often made to:

  • Annexes I and II of the European EIA Directive, which respectively list projects subject to mandatory EIA and non-mandatory EIA; and
  • Annex E of the World Bank Operational Directive on EA, which is illustrative and provides a framework for screening.

Use of these lists is reported by the World Bank to be a reliable aid to the classification of proposals into one of three categories (see Box 1):

  • projects requiring a full EIA because of their likely environmental effects (see Box 2);
  • projects not requiring a full EIA but warranting a further level of assessment (see Box 3); and
  • projects not requiring further environmental analysis (for example health and nutrition, institutional and human resource development and technical assistance).

Listed projects provide a standardised framework for screening proposals.

This approach is simple to apply, at least in its most basic form of identi-fying

the type and size of project for which EIA is mandatory or almost certainly

required. However, project lists should be used cautiously and with due

regard to their weaknesses, especially if they are the sole basis for screening.

The automatic application of EIA to proposals may be avoided by staying just

below the predetermined size threshold; for example building a major road in

19 km sections when the threshold for inclusion is 20 km. Secondary project

lists or other screening procedures should be in place to ensure such

proposals are subject to the appropriate level of EIA.

World Bank and international experience indicates that project lists should be

used flexibly in screening proposals. Reference should be made to the location

and setting of the proposal, as well as its scale. A low-head hydropower dam

or small-scale quarry (<100 ha) normally would not merit full EIA (e.g. by

reference to the World Bank Annex E lists). However, the proposal may need

to be reclassified if it is located in or near sensitive and valued ecosystems, or

heritage resources, displaces people who are particularly vulnerable and

difficult to resettle or has evident cumulative impacts (e.g. one of a series of

quarries or dams). The methods available for this purpose are discussed


As necessary, project lists should be revised and updated over time to

incorporate increasing experience and to respond to new demands. The

reform of project lists and thresholds preferably should take place through a

consultative process, involving government agencies, industry and the public.

When developing project lists from scratch, care should be taken not to adopt

those established elsewhere without adequate review of their suitability.

Project lists are drawn up with reference to the developmental and physical

characteristics that are particular to a country or jurisdiction, and it is unlikely

they will to be directly transferable without alteration.

Box 1: Environmental screening – World Bank classification
Projects or components
Category A: for projects likely to have significant adverse environmental impacts that are serious (i.e., irreversible, affect vulnerable ethnic minorities, involve involuntary resettlement, or affect cultural heritage sites), diverse, or unprecedented, or that affect an area broader than the sites of facilities subjectto physical works. A full EIA is required. • dams and reservoirs

• forestry and production projects

• industrial plants (large scale)

• irrigation, drainage, and flood control (large scale)

• land clearance and levelling (large scale)

• mineral development (including oil and gas)

• port and harbour development

• reclamation and new land development

• resettlement and new land development

• river basin development

• thermal and hydropower development

• manufacture, transportation, and use of pesticides

• other hazardous and/or toxic materials
Category B: for projects likely to have adverse environmental impacts that are less significant that those of Category A projects, meaning that few if any of the impacts are likely to be irreversible, that they are site-specific, and that mitigation measures can be designed more readily than for Category A projects. Normally, a limited EIA will be undertaken to identify suitablemitigation and management measures, and incorporate them into the project. • agro-industries

• electrical transmission

• aquaculture and drainage (small-scale)

• irrigation and drainage (small-scale)

• renewable energy

• rural electrification

• tourism

• rural water supply and sanitation

• watershed projects (management or rehabilitation)

• rehabilitation, maintenance, and upgrading projects (small-scale)
Category C: for projects that are likely to have minimal or no adverse environmental impacts. No EIA is required. None
Source: World Bank (1993)

An example of a project list for screening can be found in the resource material

at the end of this topic (Handout 4-1).

 Case-by-case screening is carried out when the significance of the potential

environmental impact of a proposal is unclear or uncertain. This process

typically applies to proposals that fall just below or close to the thresholds

established for listed projects. In addition, non-borderline proposals may be

subject to screening if they are located in sensitive areas or there is a potential

for cumulative effects in combination with other current and foreseeable

activities. The framework outlined in Figure 1 contains a sieve of screening

applications with a progressively finer mesh for including proposals. It has

gained a degree of international acceptance as a standard of good practice.

The specific criteria for case-by-case screening differ from country to country.

Typically, however, they are based on a number of common factors related to

the consideration of the significance of environmental impacts. These include

the location of proposals, environmental sensitivity and any likely health and

social effects on the local population. In this context, reference may be made to

the screening criteria listed in the European Directive, which apply to the

selection of listed projects for which EIA is not mandatory.

These criteria may be adapted to wider use in case-by-case screening. A

proposal can be tested for significance by taking account of:

  • location near to protected or designated areas or within landscapes of special heritage value;
  • existing land use(s) and commitments;
June 12, 2006 Uncategorized — brendan @ 4:16 pm

1 Comment »

  1. Thanks for the wonderfully prepared and enlighting notes!

    Comment by Clive — February 28, 2012 @ 11:27 am

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