Sustainable Air Quality

ME 449

Jan 13, 2002

Health Care

The physicians evaluate a patient’s health by measuring the temperature, pulse rate, the cholesterol level and other vital signs. For diagnosis, doctors use many tools, like x-ray images, ultrasound scans, usually in combination.

Living Earth

The Earth is also like a living organism. Following James Lovelock, it has become necessary to monitor the health of people as well as the health of planet Earth itself.

The Earth is constantly changing due to physical aging and evolution of the biosphere. Some of the changes occur slowly in a steadily and foreseeably, other changes occur quickly, unexpectedly, and unevenly in space and time. From human point of view, many of these abrupt changes are catastrophic events.

Some of the changes, short and long term, are caused by human activities and those are controllable.

Explaining Change

The basic elements of life including carbon, nitrogen, phosphorus, calcium are in constant circulation between the earth’s major environmental compartments: atmosphere, hydrosphere, lithosphere, and biosphere. These earth’s compartments remain in balance as long as the rate of flow of matter and energy in and out of the compartments is unchanged.

Changes in the environmental compartments will occur if the circulation (in and out flow) of the substances is perturbed. For example, the concentration of atmospheric carbon dioxide in the atmosphere has been increasing because the rate of input is larger than the rate of output from the atmosphere.

Major Biogeochemical Processes Visualized by Aerosols

Dust storms

Volcanoes Anthropogenic pollution

These processes are producing visible aerosols in form of dust, smoke, and haze. The quantity and spatial-temporal distribution of dust and smoke and haze can be used to characterize the flow of substances through the atmosphere.

Fires

Sensory-Motor Response to ChangesRegardless whether the Earth is considered ‘healthy’ or ‘sick’, the inevitable and unforeseeable environmental changes require response to these changes: The response includes the following major steps:

The above three steps are the necessary conditions for sustainable development. This is logical since all living organisms use this type of sensory-motor feedback to maintain their existence.

Sensing and recognition (monitoring)

Reasoning and explaining (sciences)

Decision making, action (management)

Sensing and Monitoring

Today’s earth scientists evaluate the physiology of planet earth also by monitoring the temperature, carbon dioxide, ozone, biomass, cloudiness, and many other parameters as the vital signs of the interconnected Earth System.

The observational instruments of earth sciences include thermometers, chemical sampling analysis of air, land and water, as well as earth observing satellites.

Dust storms, forest fires, volcanic emissions and anthropogenic fuel combustion are major biogeochemical processes that are visualized by aerosols.

Air Quality Management: Closed Loop

EnvironmentAssessmentCompare to GoalsPlan ReductionsTrack Progress

Controls (Actions)

Monitoring(Sensing)

Set GoalsCAAA

NAAQS

Assessment turn data into useful knowledge through Data Analysis

Multi-sensory data are collected through Monitoring

The Earth System• Atmosphere

– Conveyer of mass, moves mass source to receptor

– Small storage capacity• Hydrosphere

– River system – conveyer collects substances in watershed

– Oceans – long-term geochemical reservoir

• Lithosphere– Solid shell of inorganic matter at

surface of the Earth made of up of soil particles and rock down to 50km

– Within soil, biochemical reactions by microorganisms are responsible for most of the chemical changes of matter

• Biosphere– Thin shell of organic matter on the

Earth’s surface (occupies the least volume)

– Chemical pump for much of the flow of matter through nature

– Responsible for grand scale recycling of energy and matter on the Earth

Source Types and Emissions• Primary pollutants

– Substances that are emitted directly into the atmosphere– E.g. VOCs, NOX, CO, particulate matter (PM)

• Secondary pollutants– Pollutants formed in the environment through chemical or

photochemical transformations of primary pollutants– E.g. tropospheric ozone, PM

• Anthropogenic sources– Cars: NOX, VOCs, Pb, CO– Power plants: NOX, CO2, CO, SO2

– Agriculture: PM, NH4

• Natural sources– Wind blown dust: PM– Plants: VOCs– Volcanoes: SO2, PM– Fires: smoke (PM), CO2, Hg

Effects of Air Pollution

• Air pollution affects the following:

– Human health (acute and chronic effects)

– Animals– Plants– Materials– Visibility– Climate

Pollution Exposure (Dose)

• The activities of humans result in direct emissions of pollutants to the atmosphere

• Once airborne, these pollutants are transported, transformed, and concentrated

• The resulting pollutants may have negative effects on humans, plants, animals, and nature

• As a result of negative effects, laws and regulations are promulgated to either alter the activities or control their emissions with “end of the pipe” controls. Both of these strategies aim to reduce emissions.

Air Quality Management Feedback System

Example: London Fog• Population: London, a cold December week in 1957• Activity: home heating using soft, high-sulfur coal

• Emissions: SO2

• Transport: low wind speed – SO2 is accumulated

• Chemical transformation: SO2 SO42- acid aerosols

(H2SO4)

• Effect: 4000 deaths above normal (2.6% increase)• Regulation: Reduce the use of soft coal• Change Activity: fuel switching – change to hard coal, oil,

gas, electricity

Just like the human eye, satellite sensors detect the total amount of solar radiation that is reflected from the earth’s surface (Ro) and backscattered by the atmosphere from aerosol, pure air, and clouds. A simplified expression for the relative radiatioin detected by a satellite sensor (I/Io) is:

I / Io = Ro e- + (1- e-) P

Satellite Detection of Aerosols

Today, geo-synchronous and polar orbiting satellites can detect different aspects of aerosols over the globe daily.

where is the aerosol optical thickness and P the angular light scattering probability.

Height Type Size Angle Shape

dHdCdDdPdSSPDCHI