This document discusses various methods for environmental impact assessment and calculating pollution indices. It outlines 8 common methods for environmental impact assessment, including checklists, matrices, and predictive/simulation methods. It then focuses on the environmental medium quality index method, describing how factors are identified and assigned weights. The document provides examples of calculating air and water quality indices. The air quality index calculations compare pollutant concentrations to standards, while the water quality index is based on 9 key variables like dissolved oxygen and turbidity. Pollution indices provide a standardized way to measure and compare environmental quality.

1. SANDESHA K M
2ND Sem M Tech(WRE)

2. Environmental Impact Assessment Methods
List of Environment EIA Methods:
1. Adhoc method
2. Checklists method
3. Matrices method
4. Networks methods
5. Overlays methods
6. Environmental index using factor analysis
7. Cost/Benefit Analysis
8. Predictive or Simulation methods

3. Environmental Medium Quality Index Method
Generic steps are associated with the development of numerical indices or
classification of environmental quality or pollution potential of human activities which
include factor identification, assignment importance weights or other methods for
factor evaluation.
Factor identification basically consists of delineating key factors that can be used as
indicators of environmental quality susceptibility to pollution, or the pollution potential
of the source type.
Factor identification should be based on the collective professional judgement of
knowledgeable individuals relative to the environmental media or pollution-source
category. Organized procedures such as the Delphi approach ,can be used to aid in the
solicitation of this judgement and the aggregation of the results (Linstone and
Turoff,(9)).

4. Air Quality Index
• Any pollution index should indicate the gross level of pollution with reference
to the standard limits of the individual pollutants.
• It should be easy to understand and should include the major air pollutants. If
the use of indices is to be made on a national/local level care has to be taken
to include always the same air pollutants to maintain parity.
Calculations of Air Pollution Indices
There are a number of methods, which are used to calculate the air pollution
indices. Some of these are mentioned below.
1. In one of the methods the important individual pollutants are compared with
their ambient air quality standards in terms of percentage and the air pollution
index (API) is calculated by taking their average. If there are three pollutants,
then
API=1/3 𝑖=1
3
𝐴𝐼
AI= CI/ SIx 100, where CIthe concentration of the pollutant I and SI is the
standard value of the pollutant in ambient air.

5. 2. In this method, ratios of three important air pollutants to their ambient air
quality standards are first obtained and then the average of their sum is
multiplied by 100.
API=
𝐼𝑃𝑀
𝑆𝑆𝑃𝑀
+
𝐼𝑆𝑂
𝑆𝑆𝑂
+
𝐼𝐶𝑂
𝑆𝐶𝑂
* 100
Where IPM, ISO,ICO represents individual values of particulate matter, sulphur
dioxide and carbon monoxide and SPM,SSO,SCO their ambient air quality
standards.
3. In another method, subindices(AI) are first obtained for five air pollutants by
giving them arbitrary numbers according to their range of ambient
concentrations as indicated in the table. The air pollution index is the then
calculated as the sum of these subindices.
API= 𝑖=1
5
𝐴𝐼

6. Sub index value (AI) for five important air pollution parameters to calculate air
pollution index.
4.The air pollution index can also be calculated on the basis of a single parameter
taking into consideration only the dominant pollutant. For example, index for
sulphurdioxide can be represented as follows.
API=
𝐼𝑆𝑂
𝑆𝑆𝑂
∗100 where ISOand SSOare ambient SO2concentrations, and
the air quality standard respectively.

7. All above indices have been calculated on percent basis, a common rating scale
given below can be used to indicate the air quality.
Air quality rating scale.

8. The Pollution Standard Index
• This index makes it possible to compare the air quality of different urban areas
and its potential threat to human health. The EPA has established acceptable
standards of air pollution. that is, National Ambient Air Quality Standards
(NAAQS).
• If a pollutant in a city is at the standard, it is given an index rating of 100. Any
index value below 100 suggests relatively clear air with minimal health effects.
However, as the index value rises to above 100, the air is progessively more
polluted and the health effects correspondingly severe. Any index value of 400
or above suggests air pollution. It may cause premature death of sick and
elderly.

9. Pollutant Standard Index Breakpoints

10. Water Qualities Index
• For calculating the water quality index the ninc individual variables of greatest
importance identified are dissolved oxygen (DO),fecal coliformed, pH, 5-day
biochemical oxygen demand (BOD), nitrates (NO), phosphates (PO ).
temperature deviation, turbidity (in JTU), and total solids (TS). ). The resultant
importance weights based on the ratings for each variable are listed in Table.

11. Pollutant standard index breakpoints
1

12. • The water rating curve for each of these parameters would number with 0-100
water rating scale on the y-axis and actual level of each parameter on the x-axis on
graph.
• s

13. • To calculate the aggregate water quality index either weighted leaner sum of the
subindices (WQ la) or a weighted project aggregate function (WQ Im) can be
used. These are expressed mathematically as
WQ Ia = 𝑐=𝑙
𝑛
𝑤𝑖 𝐼𝑖
WQ Im =π𝑛
𝑖 = 1𝑙𝑖 𝑊𝑖
• Sub Index I =
𝐸𝑞𝑢𝑎𝑙𝑖𝑡𝑦 𝑄𝑢𝑎𝑙𝑖𝑡𝑖𝑒𝑠
𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡𝑎𝑙 𝑄𝑢𝑎𝑙𝑖𝑡𝑦 𝑆𝑡𝑎𝑛𝑑𝑎𝑟𝑑
*100

14. THANK YOU