- Slides: 20
1. Introduction In this chapter you will learn • How to anticipate and rank risk quantitatively • The legal definition of air pollution • Generic classes of air pollution control system • How to computer pollutant concentrations • How to compute properties of ideal mixtures of gases and liquids • How to compute the composition of chemically reacting gases
• What is it not a poison? All things are poison and nothing is without poison. It is the dose that makes a thing a poison. [Paracelsus, 1493 -1541]. • Hazard=> potential to harm • Risk=> probability of harm • Noxious=> harmful • Obnoxious=> unpleasant
1. 1 Prevention and control of air pollution • The environment affects our health, and our activities affect the environment • Our technological activities have an impact on the environment no matter how efficient our technology may be. • The relationship between environmental pollutants and illness is often complicated by natural causes of disease difficult to document this relationship (pollutants – illness) • Also, air quality - inside residences - vehicles - public building maybe more important than outdoor air quality
Figure 1. 1 Elements of air pollution generation, prevention and control
Definition of air pollution – A Penn State Example The presence in the outdoor atmosphere of any form of contaminant including but not limited to the discharging from stacks, chimneys, openings, buildings, structures, open fires, vehicles, processes, or any other source of any smoke, soot, fly ash, dust, cinders, dirt, noxious or obnoxious acids, fumes, oxides, gases, vapors, odors, toxic or radioactive substances, waste, or any other matter in such place, manner, or concentration inimical or which may be inimical to the public health, safety, or welfare or which is, or may be injurious to human, plant or animal life, or to property, or which unreasonably interferes with the comfortable enjoyment of life or property.
Legal Definition of Air Pollution • Note the following important areas of authority - outdoor atmosphere - contaminants at concentrations - inimical to public health, safety or welfare - injurious to human, plant or animal life or property - interferes with enjoyment of life or property Does definition pertain to indoor or workplace environment?
Rules to abate pollution • A cardinal rule: To prevent pollutants from the being produce in the first place • Seeking corrective measures such as “addon” device to capture pollutant. • Pollution prevention strategies: - Category 1. Administrative controls - Category 2. Engineering controls - Category 3. Pollution control systems
Category 1. Administrative controls • A. Establish work rules and practices that specify how processes are to be operated to prevent/minimize the generation of pollutants. • B. Establish maintenance, housekeeping, and waste disposal practices that prevent/minimize the generation of pollutants • C. Establish administrative procedures and a managerial structure to implement actions (A) and (B).
Category 2. Engineering controls • Eliminate the use of polluting materials • Substitute less polluting or nonpolluting materials • Enclose the process so that polluting materials will not be emitted to the atmosphere. • Alter the process to require minimal amounts of polluting materials. • Change the product so that polluting materials are not needed.
Category 3. Pollution control systems • Air pollution control systems are “tailpipe” devices to remove pollutants from a gas stream prior to its discharge to the atmosphere. • “Tailpipe” solutions are employed if Categories 1 and 2 are insufficient. • Control systems are engineering activities to remove pollutant gases and vapours from a discharge gas stream to satisfy government or more stringent company emission standards.
Example 1. 1 Surface coating and cleaning processes • Consider the airbone solvents (volatile organic compounds, VOCs) generated by coating, treating, and cleaning surfaces in the following applications: - Furniture: gluing, staining, finishing - Automotive vihicles, houses, aircraft, boats, etc: painting - Parts: cleaning, degreasing, stripping - Textiles: dying and treating, dry cleaning
Solution • Eliminate the use of polluting materials - use water-based coatings instead of solvent-based coating • Substitute less-polluting materials - Use coatings with lower solvent contents • Enclose the process - Use surface cleaning devices that totally enclose the cleaning process and require parts to enter and leave through airlocks • Alter the process • Change the product - Use plastics or stainless steel that do not require coating or degreasing
1. 2 Risk versus Benefit for Voluntary and Involuntary Activities • Voluntary risk=risk individual consciously undertake. motor cycles, sky-diving, recreational activities, smoking, speed limit 65 MPH vs. 55 MPH • Involuntary risk=risk taken without an individual’s consent elevators in tall building, commercial aircraft, polluted air and water • Some risk are unclear - wood stove pollution: voluntary to you but involuntary to your neighbour - highway automobile accidents: voluntary to you but involuntary to someone your car strikes
Comparing wood-burning emissions and smoking • The concentration of - carbon monoxide (CO) - total suspended particles (TSP) - several polycyclic aromatic hydrocarbons (PAHs) in home using wood-burning stoves ~ in public places where smoking is allowed
Fig 1 -2 Risk versus benefit for various kinds of voluntary and involuntary activities.
What is the root of public acceptance of risk not directly under one person’s control? • In slicing bread: - Let A be the distance between your one hand holding the bread and the other hand holding the bread - Let B be the distance between your one hand holding the bread, and the other person’s hand holding the knife - Which value (distance) is larger, A or B? Confidence is the root of public acceptance of risk not directly under one person’s control