1. A Brief History of Air Pollution and the Clean Air Act
Ronald Pope, PhD
Date: 1/12/18

2. What is Air Pollution?
Environmental Protection Agency Basic Definition:
An air pollutant is any substance in the air that can cause harm to humans or the environment. Pollutants may be natural or man-made and may take the form of solid particles, liquid droplets or gases.

3. Early Sources of Air Pollution
*Metallurgy
*Heating or Cooking
*Ceramics
Air pollution is not a recent phenomenon
*Tanning of Animal Skins

4. Early Modern Pollution Sources
Industrial Age
18th-19th Century: Coal/steam powered industry
19th Century: Emerging chemical industry.
The industrial age, and the burning of coal in factories and other industries, brought about wide-scale air pollution problems in industrialized cities, with England being infamous for intense pollution coming from its manufacturing centers during this time. This pollution was bad enough to change the local ecology; an oft-told example of natural selection in evolution regards the peppered moth in England. Prior to the 18th century, the populations of adult peppered moths in England were almost entirely light-colored, giving them effective camouflage when resting on light-colored bark or lichens. Following the industrial revolution and the introduction of coal-burning factories, the trees surrounding London and Manchester were coated with soot and pollution killed-off much of the lichens, leaving the light-colored moths exposed on a darker background. Bird predation decimated the population of light-colored moths, but the dark-colored moths were now much better camouflaged and had a higher survival and reproduction probability. By the end of the 19th century, almost all the population of peppered moths were of the dark-colored variety. As the pollution situation improved in the 20th century and lichens on the trees returned, numbers of the light-colored variety have rebounded.

5. Modern Pollution Sources
Modern Age
Automobiles popularize petroleum use.
Modern Petrochemical industry.
Motor vehicles are usually the largest source of air pollutants in an urban area, followed by industrial processes and stationary fuel combustion.

6. Air Pollution Disasters in the Early 20th Century
A series of air pollution disasters occurred in the early 20th century in both Europe and in the United States. These disasters, once scientists had discovered the connection between the pollution and the mortalities and morbidities, served to galvanize the public to demand regulation of air quality. Thus the clean air movement was born, first in Europe and then later in the U.S., which eventually led to the Clean Air Act in the U.S. and similar regulations around the world.

7. Temperature Inversions
The disasters mentioned here all occurred in the fall or winter and have weather conditions in common which led to the buildup of deadly concentrations of air pollutants. Wind conditions were stagnant and the atmosphere was vertically stable as deep temperature inversions set up and trapped pollutants near the surface.
Temperature inversions, which can occur any time of the year, are especially prevalent during cold, clear nights when radiational inversions set up. In this scenario, the earth’s surface cools faster than the air above it, and in turn cools the lower levels of the atmosphere. Thus as altitude increases air temperature increases (known as a negative lapse rate) which serves to create a stable atmosphere which acts like a blanket or lid, trapping air pollution close to the ground.
Other types of temperature inversions include subsidence inversions, where a high-pressure system will cause air aloft to sink, increasing in temperature adiabatically as it does so. This air mass can gain a temperature higher than the air mass below it, causing a temperature inversion. Another type is a frontal inversion when the fronts of two air masses meet and interact and the warmer mass overruns the cooler mass.

8. 1930 Meuse Valley Fog, Belgium
Heavily industrialized Meuse Valley in Belgium experienced 3 day “fog” in early December
60 deaths
6000 sick
Very stable weather conditions in the industrialized region of Liege from Dec 1 to Dec 5, 1930 caused 60 deaths from respiratory disease.
Major culprits were SO2, fine particulates, and thus sulfuric acid.
This episode led to the first scientific proof of the potential for atmospheric pollution to cause deaths and disease.

9. 1931 Manchester, England 9 day “fog” in January 592 deaths
Another winter-time event, mostly SO2 from coal-burning. This episode spurred grass-roots activism and pollution regulation in England.

10. 1948 Donora, Pennsylvania
5-Day fog starting October 27th, caused by temperature inversion.
20 deaths
7000 sick
Often called one of the worst air pollution disasters in our nation’s history. Even ten years after the incident, mortality rates in Donora were significantly higher than in other communities nearby.
Emissions were hydrogen fluoride and sulfur dioxide from the steel and zinc mills. This merged into a smog containing sulfuric acid, nitrogen dioxide, and fluorine.
The fog started building up on Oct 27; plant operators would not agree to shut down their mills until Oct 31, though it rained on the 31st and the plants started operating again.
This event is credited with helping to trigger the clean-air movement in the United States.
Taken at noon, Oct

11. 1952 London Smog Disaster (AKA The Big Smoke)
Cold, stagnant air caused coal emissions (SO2) to accumulate during five day event in early December.
4,000-13,500 premature deaths
>100,000 sick
Cold, stagnant air collected pollutants, mostly coal emissions, in a smog that formed a thick layer over the city.
It lasted from December 5 – 9, 1952.
In some parts of the city visibility was down to less than a meter during the day. Transportation, including ambulances and public transports (except for the subway) was forced to stop functioning.
Immediate deaths during this week were more than 4,000. Most of the deaths were due to hypoxia as a result of mechanical obstructions in the airway from pus arising from lung infections caused by the smog.
Further research has found that deaths from December 1952 to March 1953 were 13,500 higher than normal.
This is known to be the worst air-pollution event in the history of the UK, and most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health.

12. Air Pollution Legislation
The Clean Air Act

13. Air Pollution Legislation
Early control legislation was mostly local and aimed at smoke control.
Prior to 1950 there was no significant legislation anywhere in the world.
1947-California passed first state air pollution law.
1955-First ‘Clean Air Act’ was passed, but limited in scope and effectiveness.
King Edward I of England
Most of the early control legislation was local in scope and aimed at smoke control; e.g. Edward I of England banned the burning of sea coal in 1307 and made it a hanging offence. In the United States, there were only limited municipal ordinances regarding smoke and ash in the late 19th and early 20th centuries.
California passed the first state law in 1947.
But with the ever worsening pollution conditions, and the realization that air pollution is not just local in scope, attempts were made to pass federal legislation between , including the initial ‘Clean Air Act’ (actually ‘Air Pollution Control Act’ ) which was passed in This was amended six times between These laws had various provisions, but were mostly ineffective.

14. Air Pollution Legislation
1970- Amendments to the Clean Air Act was signed into law by Richard Nixon
Historic in nature
In same year Nixon created EPA by executive order.
Goal was to have clean air throughout the nation by 1975!
Studies showed air pollution continuing to worsen across the nation, despite previous efforts. Congress viewed states as weak and subject to industry pressure, and so they passed the amended Clean Air Act in 1970, which was signed into law by Richard Nixon.
This law, at over 3500 pages, was the most ambitious yet and then Nixon created the Environmental Protection Agency to oversee it.
This law set up the modern structure of pollution regulation, including:
Air Quality Standards (one of the most important amendments).
Automobile emissions
Pollution control at sources
Control of toxics
Enforcement at the Federal level.
Research funding.
Major goal was achievement of clean air throughout nation by 1975 (how’s that for positive thinking?).
President Nixon signs Clean Air Act on December 31, 1970

15. Air Pollution Legislation
1990-Clean Air Act amendment was signed by George H.W. Bush.
One of the most far-reaching and complex laws ever passed, rivals IRS code.
Greatly enhanced the 1970 Clean Air Act.
The 1970 CAA is considered landmark legislation, but ultimately it was not successful and so was replaced with Clean Air Act Amendments of 1990.
George Bush signed this into law.
The 1990 Clean Air Act added more regulatory programs including:
Expanded air quality standards.
Acid rain control.
Operating permits for polluting industries.
Greatly expanded toxic and hazardous air pollutant control with 189 toxic chemicals.
Stratospheric ozone protection
Increased enforcement.
Expanded research programs
President Bush signs Clean Air Act Amendments on November 15, 1990

16. Components of the Clean Air Act
The Clean Air Act has been successful in many ways, as seen in the overall improvement of air quality in our major cities. There is still much to be done, however.
Los Angeles, CA

17. The Clean Air Act Regulates:
Motor Vehicle Emissions
Permits for Industrial and Commercial Sources of Air Pollution
Stratospheric Ozone Protection
Acid Deposition Control (Acid Rain)

18. Visibility and Regional Haze
The visibility and regional haze section of the CAA is designed to protect the pristine areas of our country, i.e. national parks and wilderness areas. The idea here is to protect the beauty of these areas so that our children can enjoy these spaces as their forefathers did. These laws impose special restrictions on facilities if it is believed their emissions will have impact on national parks or wildness areas.
Grand Canyon National Park Visibility

19. Toxic and Hazardous Air Pollutants
187 chemical pollutants listed, such as:
Asbestos
BTEX (from gasoline)
Benzene
Toluene
Ethyl benzene
Xylenes
Styrene (from fiberglass)
Perchloroethylene (dry cleaning solvent)
Heavy metals (such as mercury or lead)
Health Effects could include:
Increased risk of cancer
Targeted damage to body systems (immune system, neurological, or respiratory)

20. Criteria Air Pollutants
Carbon Monoxide (CO)
Lead (Pb)
Nitrogen Dioxide (NO2)
Ozone (O3)
Particulates (PM10 & PM2.5)
Sulfur Dioxide (SO2)
Dust Pollution (PM10)
Criteria pollutants are the most recognized of the air pollutants, and are the only pollutants with ambient air quality health standards. They were first identified in the 1970 CAA because they were the most wide-spread of the air pollutants and could be found in any urban area in the country.
Phoenix Brown Cloud (NO2 & PM10)
Acid Rain Damaged Forest (SO2)
Smoke Pollution (PM2.5)
Leaded Gas

21. Ozone is a secondary pollutant, i. e
Ozone is a secondary pollutant, i.e. it’s not directly emitted, that is formed by chemical reaction from other chemicals within the atmosphere. Oxides of nitrogen and volatile carbon compounds combine in the presence of sunshine to create ozone. It is, however, a very complicated process with many different sub-reactions occurring in the creation of ozone.

22. Blood cells are 6-8 microns in diameter
Aerosol pollution (an aerosol is particle suspended in a gas solution) can consist of liquid or solid particulate matter. Liquids are known as mists, while solids can be fumes or smoke. Particulate matter is classified by the average size, or aerometric diameter, of the aerosol. PM10 is particulate matter of 10 microns or less, while PM2.5 is particulate matter of 2.5 microns or less. Note that PM10 would also include PM2.5 particles. In southern Arizona, PM10 is often characterized as dust particles, while PM2.5 is often thought of as smoke particles. PM2.5 also has significant a significant source in secondary formation, where sulfur and nitrogen gasses will condense into a microscopic particle (condensation nuclei). Chemical reactions can also create secondary particle pollution when two vapor molecules react to create a particle.
Note that a dust cloud usually consists of particles much larger than 10 microns with most of the airborne dust being in the PM50-PM100 range. The PM10 and smaller component became important and classified as a pollutant because scientists discovered that it is particles less than 10 microns that are able to defeat our bodies natural filtering methods (e.g. cilia and mucus in our airways) and penetrate deep within our respiratory tract, causing problems. Fine particles less than 5 microns, and especially smoke at less than 2.5 microns, is able to penetrate and deposit in the deepest point in our respiratory system, the alveoli or air sacs of the lung, and can even pass into the bloodstream causing cardiovascular as well as respiratory problems.

23. National Ambient Air Quality Standards (NAAQS)
Health standards are set for:
Exposure
Dosage
Example:
Pollutant
Exposure Time (Averaging Period)
Dosage (Health Standard)
PM2.5
Annual (Arithmetic Mean)
15 µg/m3
24-hour
35 µg/m3
Criteria air pollutants are those compounds for which a ambient concentration standard has been created, called the National Ambient Air Quality Standard (NAAQS).
NAAQS have a primary (protecting public health) and secondary (protecting property and visibility) component.
NAAQS are different for each criteria pollutant, and also have different averaging periods based upon known epidemiological evidence of health effects.

24. Monitoring Air Pollution
This picture is of the West Phoenix air monitoring station. Particle monitors are located on the platform, while gas monitors are located within the shelter with the data logging equipment. The site also contains a number of meteorological instruments such as wind speed/direction, temperature, and pressure monitors.

25. Air Monitoring Network
The Maricopa County Air Quality Department has a website with real-time air pollution data. This website can be found by clicking the “Current Air Quality” link from our homepage:

26. Questions and Discussion

28. Health Effects Handout