ENV E 556 AIR POLLUTION EXAM 1

What is an air pollutant?

A contaminant present in the air at high enough levels that has the potential to negatively impact human health, welfare, or ecosystems

What are the 6 criteria air pollutants?

CO
NO2

SO2

Lead (Pb)

PM (10 and 2.5)

Ozone

Clean Air Act Amendments of 1970

NAAQS

What is CARB?

The California Air Resources Board. The “clean air agency” of California.

Types of Major Air Pollutants

CO

NOx

SOx

VOCs

PM

Ozone

How is carbon monoxide formed?

From the incomplete oxidation of carbon. This can come from: gas appliances, forest fires, on-road vehicles, biomass burning, industrial emissions, and power generation

How are nitrous oxides (NOx) formed?

From the burning of fuels

How does NOx combust?

10% is NO2 while 90% is NO

What does the addition of sunlight do to NOx?

In the presence of sunlight NO2 converts to NO and forms Ozone

NO reacts with VOCs to form what?

NO reacts with VOCs to form NO2

What is the largest form of SOx?

Combustion of fuel in power plants and other industrial facilities

How does SO2 react ?

It reacts with the atmosphere to form SO3

and dissolves in water vapor to form sulfuric acid (H2SO4)

What’s a VOC?

A volatile organic compound. The phrase includes a number of gas organic compounds

Where are VOCs commonly found?

In household products, building materials, as well as indoors

What is Particulate Matter

Aerosols whose composition can range from 1 nm to  100 macro m

Speak on Ozone

Stratospheric ozone is good as it forms the ozone layer and protects us from UV rays

But ground-level ozone is a threat to human health

What are the primary pollutants?

NOx, SO2, COx, Particulates, lead, air toxins

What are the secondary pollutants?

Ozone, smog chemicals, sulfuric and nitric acids

Explain the greenhouse effect 

Some infrared radiation passes through the atmosphere but most is absorbed and re-emitted in all directions by greenhouse gas molecules and clouds. The effect of this is to warm the Earth’s surface and the lower atmosphere

What are the green house gases?

CO2

Methane

NO2

Fluorinated Gases

What’s some evidence of climate change?

Atmospheric CO2 levels have increased 1.5-2 ppm/yr

2014 CO2 levels (400 ppm) are 40% higher than before the Industrial Revolution 

Seasonal changes in photosynthesis and respiration cause seasonal variations in CO2 levels 

What happens to solar radiation once it enters the atmosphere?

It is either absorbed or scattered/reflected

What is albedo?

The fraction of incoming radiation reflected from a particular surface

What happens to the absorbed energy?

It eventually leaves as infrared radiation

Why does the EPA have a standardized emission regulation to 7% O2 correction?

To ensure that pollutant concentrations are reported consistently and accurately, regardless of the actual content in the flue gas. 

What are the types of of air pollution measurement methods?

Reference Monitors

Research Instruments

Remote Sensing

Air Sensors

How well does each instrument perform?

Reference Monitors, Remote sensing generally have higher rates of accuracy with a corresponding high price tag while Air sensors are less expensive but more prone to less accurate data

How do Electrochemical (EC) gas sensors work?

Measure the charge across a chemical reaction, which is then converted into a concentration

How do Metal Oxide Semiconductors (MOS) Sensors work?

Measure a change in resistance when a gas interacts with the sensor’s surface

How do Nondispersive infrared (NDIR) Gas Sensors work?

Use infrared light to detect the presence of gas molecules in the air (usually, more accurate)

What are the major indoor air pollutants?

Radon, Asbestos, Pesticide, Secondhand Smoke, Lead, Combustion Pollutants, Formaldehyde, VOCs