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EIAfinal examination

Teacher: Prof. Wei

Student: Dao Thi Huyen Nhung

Student ID: R0005038

Chapter 6

Prediction and assessment of impact

on the air environment

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Air pollution:The presence in atmosphere of one or more contaminantsin such quantities and of such duration as is or tends to be injurious to

human health, animal or plant life, or property.

List of air pollutants: Gases and particulates+ Gases: such as sulfur dioxide, oxides of nitrogen, in liquid or solid by the

changing of increased pressure or decreased temperature.

+ Particulates: solid or liquid in the range of size (0.0002 m 500 m) in

diameter.

1. AIR POLLUTION

vs. KIND OF SPECIFIC AIR POLLUTANTS

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1. AIR POLLUTION

vs. KIND OF SPECIFIC AIR POLLUTANTS

Hazardous air pollutionor Air toxics: are those pollutants that areknown or suspected to cause cancer or other serious health effects, such asreproductive effects or birth defects, or adverse environmental effects.

Examples: benzene, methylene chloride, dioxin, cadmium, mercury, chromium,and lead compounds.

Photochemical smog: in the atmosphere as a result of the photo-inducereaction of hydrocarbons and oxides of nitrogen.

Acid rain: is atmospheric reaction which exhibits a pH value less than the

normal pH of rainfall (approximately 5.7 when CO2 equilibrium isconsidered) by sulfur dioxide emissions or possibly nitrogen oxide.

Other: influence of air pollution on atmospheric heat balances andassociated absorption or reflection of incoming solar radiation.

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2. SOURCES OF AIR POLLUTANTS

Emissions from industrial stacks are regulated to protecthuman and environmental health

Industrial facilities are required to obtain permits to emit intothe atmosphere and to demonstrate their compliance withregulations

Point sources (stacks)

Line sources (roads)

Area sources (treatment ponds)

Volume sources (buildings)

Biogenics

Stacks in industry, traffic

About 60% of the emissions are

from point sources

In the process of applying for permits, dispersion models are

generally used to assess the impact of point source emission

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Determine air quality impacts of alternatives and proposed

action on the mesoscale and microscale levels

The mesoscale level assessment: measures the contribution of theproposed action to area and regional emission inventories.

The microscale level assessment: is a comparison of calculatedconcentration levels of air pollutants at specific locations to applicable

ambient air quality standards.

Both levels of impact assessment are necessary in order to adequately address

the air quality impacts associated with proposed actions.

3. APPROACH FOR ADDRESSING AIR

ENVIRONMENTAL IMPACTS

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Step 1: Identification of the types and quantities of airpollutants and of their impacts

Use techniques to find Emission factors information, it indicates theaccuracy of factor with the level affects decrease (A-> E) and containsseveral conditions: Calendar year, average speed, temperature, fuelvolatility, operating modes.

Types and quantities of pollutants that will be released from the projectsources, i.e. the emission rates of all pollutants.



Air quality impact assessment framework

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Step 2: Description of existing air quality conditions Ambient air quality data: information on air quality monitoring data.

Emission inventories: the compiled information on the quantities of airpollution from all the sources in a defined geographical area entering theatmosphere in a given time (1-yr period)

Determine meteorology and climatology: wind speed & direction, atmosphericstability classes, mixing heights, worse meteorology or a whole year of data

Step 3: Procurement of relevant air quality standards andregulations Criteria and policies will be the relevant local, state, and federal agencies

Determine the significance of air quality impacts incurred during projects; Decide between alternative actions or in assessing the need for mitigatingmeasures for a given alternative.

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Step 4: Impact prediction

Prediction and assessment of air quality impacts identify type and quantities of

air pollutants emitted from construction and operation of each alternative under

consideration for a proposed action.



Identify sources of air emissions* Constructional sources

* Operational sources

Characterize air emissions: Types of air pollutants

emission rates (constant or varying)

emission heights exit temperature

exit velocity Pollution sources and their locations

Determine air sensitive receivers (ASRs) receptor locations

receptor heights (terrain heights)

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Box-Model approaches: estimate of concentration values. It is based on the

mass conservation of a pollutant in a box.

The reference frame is Eulerian, i.e. fixed frame, rather than Lagrangrian, i.e.

reference frame moving with the velocity of the pollutant. The box or volume may

represent a city or region. The plan area over a city is represented by x, y and z in the

vertical dimension of the air shed.

Mass

balance approach: a mass balance of the total air pollutant emissions

from all sources for a proposed project or activity entering the atmosphere

during the construction and/or operational phase.Percentage

Increase

In inventory

=Projectactivity emission Inventory information (100)

Existing emission inventory information

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Mathematical model

+ Statistical Models: relate to air quality based on analysis of ambient air qualitymonitoring data.

+ Emission models: to predict emission rate from hazardous waste treatment anddisposal sites. The models are based on diffusion theory and emission ratesare calculated by determining the mass transfer coefficient of the pollutant.

+ Dispersion models: estimates of pollutant concentrations at selected locations.

These points of location are called receptors, and the network of points is the

receptor grid.

Adopt proven mathematical air dispersion models, for example,

VALLEY or ISCST model for stationary sources such as stack emission

CALINE4 model for traffic emission (line sources)

FDM for construction dust emission



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Step 5: Assessment of impact significance Refer to the interpretation of the significance of anticipated changes related

to the proposed project.

Comparison of the combined concentration (background and incrementalconcentrations) of the pollutant and the acceptable or allowable ambient airquality standards of that pollutant.

Include publish input, professional judgment, specific effects of the types ofair pollution from a proposed project or activity.

Step 6: Identification and incorporation of mitigationmeasures

Minimize the magnitude of the air quality impacts to bring the pollutantswithin acceptable level.

Revise the design as needed in order to reduce the air pollutants expected tobe emitted from the project-activity. The revised project or activity can thenbe reassessed to determine if the mitigation measures have eliminated orsufficiently minimized the deleterious air quality



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