Env Tech ch 13

list major sources/effects of indoor air pollution.

combustion products (lung cancer), radon (damages lung tissue), asbestos (mesothelioma), lead (effects central nervous system), formaldehyde (cancer), organic chemicals from household products (headaches, cancer) and biological substances (asthma).

describe the key devices used to control gaseous air pollution. what is an FGD system used for?

countercurrent tower, incineration, wet/dry scrubbers, absorption/adsorption. FGD flue gas desulfurization removes sulfur from system before it goes out into the air.

discuss major techniques and devices used to sample and measure particulate air pollutants.

dustfall bucket, hi-vol sampler, cyclone, fabric filters, electrostatic precipitators

what are the 6 criteria air pollutants regulated under the Clean Air Act? What are their major sources?

sulfur dioxide (fossil fuels) , nitrogen oxide (automobiles), carbon monoxide (incomplete combustion of fossil fuels), solid/liquid particulates (industrial processes) , particulate lead (smelting operations), and ozone/photochemical smog (motor vehicles emit nitrogen oxides and VOCs).

what is meant by atmospheric stability? how does it affect air quality?

the degree of vertical mixing of air and dispersion of pollutants. a condition of atmospheric instability is preferable to a stable condition because there is an increase of mixing and dispersion of pollutants in air.

what is the troposphere? how does it differ from the stratosphere?

the lowermost surface layer of the atmosphere which contains a large percentage of total air mass. the stratosphere is a stable layer above it and contains small amount of total air mass, contains more ozone than tropo, barrier of uv rays from sun.

give a brief definition of air pollution. what is meant by anthropogenic air pollution?

the presence of certain substances in the air in high enough concentrations and long enough durations to cause undesirable effects. Anthropogenic is caused by human activities.

combustion is a major source of air pollution. Can it also be used for air pollution control?

yes the higher the heat the more complete the combustion and fewer pollutants are emitted.

Discuss typical types and sources of hazardous air pollutants.

Asbestos & Formaldehyde (building materials). Benzene (gasoline-powered vehicles). Mercury (coal power plants).

define environmental lapse rate, adiabatic lapse rate, and temperature inversion. how does a weak prevailing lapse rate differ from an inversion? does a superadiabatic rate cause poor air quality?

Environmental lapse rate-rate of change in air temperature with altitude at a particular time and place Adiabatic lapse rate-the rate of change of temperature of mass of air as it gains altitude temperature inversion- a lapse rate characterized by an increase in actual air temperature with increasing altitude which results in extremely stable atmosphere Weak differs from inversion in that the air temperature decreases with altitude rather than temperature increase with altitude. Superadiabatic does not cause poor air quality because they are associated with an unstable atmosphere.

discuss major techniques (absorption and adsorption) and devices used to sample and measure gaseous air pollutants

Absorption involves the transfer of a gaseous pollutant into a contacting liquid. bubbler. Adsorption involves attracting and trapping gas molecules onto the surface of a solid. Colorimetric tubes.

Discuss photochemical smog. Is it a primary pollutant? Why?

Air pollution containing ozone and other reactive chemical compounds formed by a warm,dry,sunny climate and presence of nitrous oxides. No, it is a secondary pollutant that is formed by reactions of primary pollutants and not emitted directly from a source.

What is an air pollution episode? give two examples

An air pollution episode is a period of abnormally high concentration of air pollutants that cause death and illness.

Identify and discuss the major greenhouse gases.

Carbon dioxide absorbs most of the heat trapped by the atmosphere. making it the major gas. Methane although smaller in quantity has a big impact because it soaks up longwave radiation as do nitrous oxide and ozone.

Describe the basic operating principles for five particulate emission control devices for stationary sources. which of these are used primarily as precleaning devices?

Gravity Settlers-particulates settle out due to gravity when airstream velocity is reduced (precleaner) Cyclones-subjects particulates to inertial forces and friction which separates them from carrier gas Wet Scrubber- trap suspended particles by direct contact with an aerosol spray of water Electrostatic precipitator- particles in a gas stream given an electric charge and are removed from gas by the influence of an electrical field Fabric filters- removes very small particles from dirty flue gases as the gas stream passes through a special filter fabric shaped like a long inverted bag

what size range of particulates is of most significance with respect to human health? what size range of particulates will readily settle out of the air?

Less than 10um in size for human health. Those larger than 1um tend to settle out.

Discuss the potential impacts of global warming

Overall increase in precipitation, increasing in cloudiness, rising sea levels, changing ecosystems, increase danger of flooding, and change the shape of coastlines

What is the difference between primary air pollutants and secondary air pollutants? what is the difference between criteria air pollutants and hazardous air pollutants?

Primary are emitted directly into the air from a specific source while secondary are not emitted directly from a source but are formed in the atmosphere. criteria pollutants are emitted in large quantities by various sources . hazardous air pollutants are not as voluminous immediately harmful to human health (potent).

describe methods for controlling and reducing indoor air pollution.

Proper ventilation and air exchange system

Discuss the role of the wavelength of light as a factor in the natural greenhouse effect. How does the troposphere serve as a blanket to keep Earth warm?

Short waves from sun penetrate the atmosphere then are absorbed by the Earth and radiate back as long waves which cannot penetrate back into space trapping them in the troposphere. Most gases are in the troposphere where gas traps the longwave radiation causing warming of the Earth.

explain difference between source and ambient sampling.what is meant by isokinetic sampling? is there a difference between air quality sampling and air quality monitoring?

Source are air samples collected from the pollutant source. Ambient an air sample collected from the outdoor or surrounding air after pollutants from various sources have been dispersed. isokinetic is one in which the velocity of the gas stream entering the sampling probe is the same as the velocity of the carrier gas. air quality sampling refers to the acquisition of a representative quantity of polluted air/gas while monitoring refers to the collection of pollutant concentration data on a continuous basis.

discuss 5 strategies for air pollution control.

Source location, fuel substitutions for industries, correct operation for minimizing air pollution. a complete change of industrial manufacturing processes. tall smoke stacks

what is the difference between a dust and a fume? between a mist and a spray? is fly ash synonymous with a smoke?

Suspended solids 1 to 100um are dust particles while smaller solids less than 1um are a fume. A suspension of liquid particles between 0.1 and 10um in size is a mist whereas a spray consists of liquid particles greater than 10um. Yes.

with regard to air pollution regulations, discuss the meanings of threshold limit values, emission standards, and ambient standards.

TLV set limits to exposure of workers in industrial environments to specific vapors/dusts that have well recognized cause and effect health relationships. Emission standards focus on the major municipal and industrial generators of air pollutants for both stationary and mobile sources. Ambient focus on the allowable levels of outdoor atmospheric pollutants.

what is acid deposition? discuss its causes and effects.

The fall out of sulfuric acid and nitric acid. It is caused by emission of sulfur and nitrogen oxides into the atmosphere , from burning of coal and automobiles. The effects are lowering pH in lakes and rivers, disrupting reproductive cycles of fish, and leaching of heavy metals into drinking water.

Explain the difference between the anthropogenic greenhouse effect and the natural greenhouse effect. Why is the term greenhouse effect not completely accurate as a synonym for global warming?

The natural greenhouse effect is a normal warming result of the Earth's atmosphere due to increasing levels of CO2 and other gases, while the anthropogenic greenhouse effect is considered to be a direct result of the accumulation of trace gases in the air from human activities. If carbon dioxide level rise heat is unable to escape which causes global warming. The extent of the greenhouse effect causes global warming.

what is the major cause of stratospheric ozone depletion?

The presence in the atmosphere of organic chemicals called chlorofluorocarbons (CFCs).

why is stratospheric ozone not considered an air pollutant? what is the ozone hole, and what harm is done by global ozone depletion?

The stratospheric ozone layer blocks most of the harmful UV rays coming from the sun, thus protecting plants and animals. The ozone hole is an ozone-depleted region that seems to occur each year from August to November encompassing an area the same size as Antarctic continent. Ozone depletion allows for more UV radiation to reach the ground which is linked to human skin cancer, eye cataracts, species of plants harmed, and adding to the formation of photochemical smog.

Discuss the adverse health effects of the six criteria air pollutants. What are some other harmful effects of air pollution in addition to those on human health?

eye and throat irritation, coughing, and chest pain, bronchitis, emphysema, and other lung diseases. Air pollution causes damage to material objects, corrosion of metals and the weakening of textiles. Damage trees, flowers, fruits, and vegetables.

describe three types of temperature inversions. How do they affect air quality? Which type of inversion causes fumigation?

frontal inversions-develop at high altitudes when a warm air mass overruns a cold air mass, they are not important with regard to air quality control subsidence inversion-high altitudes when a large warm mass of air subsides or descends over a community, forms a cap that traps pollutants from vertical mixing. Cause fumigation which develop near ground level and result in very high ground-level pollutant concentrations radiation pollutants- low altitudes when earth's surface cools due to radiation of heat into space. The air in contact with ground drops in temp with warm layer above causing pollutants to be trapped. fumigating conditions are common but are not long lasting.

describe the basic emission control techniques for highway vehicles. what RFG?

hybrids/solar powered, compression ratio and timing of spark plugs, Catalytic converter burns fuel to greater completion, alternative fuel choices. RFG-reformulated gasoline program, is an oxygenated fuel containing at least 2 percent of oxygenates by weight.

sick building syndrome

indoor air pollution in an office building, characterized by unspecific illness among occupants

what are typical units of measurement of gaseous and particulate air pollutants? do they all vary with air temperature and pressure?

mass basis (mg/m^3) (ug/m^3) (ng/m^3) volume basis (ppm). Values in volumetric (ppm) do not vary with temp and pressure whereas they do for a mass basis.

what are the major gaseous constituents of fresh (clean) air?

nitrogen and oxygen

list three sources and types of natural air pollutants.

particulates from smoke/gas from forest fires, windblown dust from deserts, and pollen grains from plants