Technology Review, Oct 2009 Assignments: Wind Assignment Due Thurs. Nov 5 Study Quizzes for Chap 15 and Chap 19 “Due” Tues. Nov. 10.

Chapter 19: Air Pollution and Noise Living and Working in a Healthy Environment

Sources of the 5 major pollutants in the U.S Note: Historically, the 6 th Major Pollutant was lead.

Source and Composition of Particulates sulfates, ash sea salt meteoritic material Soot, NOx, VOCs Soot, organic soot methane, ammonia soot Soot, sulfates, VOCs Minerals, clays

Let’s consider those compounds that the Federal Government regulates  National Ambient Air Quality Standards (NAAQS) The Clean Air Act requires these standards to be set at levels that protect public health with an adequate margin of safety and without consideration of cost. Secondary standard: Necessary to protect the public welfare and the environment The light gray standards have been recently added. Primary standard: Necessary to protect the public health Texas Air Quality

Lecture 32 Texas Air Quality

U.S. Federal Regulation of Air Pollution  Air pollution Control Act of 1955  Clean Air Act of 1963  Amendment to CAA - Motor Vehicle Air pollution Control Act of 1965  1970 Clean Air Amendments and formation of the EPA.  1975 catalytic converter developed.

U.S. pollution trends since 1977 Signs that regulation works!

Types of SMOG 1. Industrial London Smog – combination of smoke and fog - At the end of the 1800’s, 40% less sunlight in London than surrounding towns - Health effects - Vitamin D deficiency, Rickets, Tubercolosis

2. Photochemical Smog  Consists mainly of secondary pollutants: Ozone (O 3 ), NO 2, VOCs Forms when sunlight induces chemical changes in gases and aerosols Causes poor visibility, burning eyes, sore lungs, worsen conditions of the heart and lungs, possible mortality.

Photochemical and Industrial Smog “LA Smog”: Brown-air smog in Los Angeles “London Smog or Industrial Smog” Gray-air in New York City © Dean D. Fetterolf/ShutterStock, Inc. © Chad Littlejohn/ShutterStock, Inc.

Photochemical Smog Ozone (O 3 ) in the Troposphere Most problematic air pollutant in many areas of the U.S. Ozone is not directly emitted into the atmosphere, but instead forms through a complex series of reactions. It is largely because of this complexity that ozone is so difficult to control. I usually apologize for the excessive chemistry here, but explain that it’s impossible to discuss tropospheric ozone without it. Explain that h simply indicates that a photon is absorbed by the molecule, which leads to decomposition (i.e., photolysis). The is just frequency.

Ozone chemistry (gas-phase only) NO 2 NO O3O3 HO 2 RO 2 OH N2O5N2O5 NO 3 HNO 3 VOC HONO h H2OH2O h H2O2H2O2 This represents a simplistic overview of the gas phase reactions involved in ozone production. I highlight NOx and VOCs since these are the precursors that we can control.

The next two slides are meant to accompany a discussion of how emissions rates are measured. Measuring what comes out of a stack is pretty straightforward. Measuring the thousands of small leaks in a massive refinery such as those in Houston is more challenging. During TexAQS2000 aircraft measurements indicated that VOC emissions from many of the refineries in Houston far exceeded the reported values.

Measuring auto and truck emissions is usually accomplished by either putting the vehicle on a dynamometer and sampling the exhaust, or by sampling pollutant levels in tunnels. The Caldicott tunnel shown above (near San Francisco) has been used extensively for the latter type of study since it has two bores, one of which is used only by cars. This permits separation of the auto emissions from those from diesel trucks.

NOx and VOC sources in the Greater Houston Area The take-home message from these figures is that NOx is emitted almost entirely as a result of combustion, whereas VOC emissions are often dominated by other sources such as trees. The refineries and chemical plants in Houston are important sources of a range of VOCs.

This is called an ozone isopleth diagram, and shows the ozone concentration that will result from different NOx / VOC mixtures. The plot on the previous slide essentially represents a vertical line here.

This shows the number of exceedances in Houston over the past 9 years. Most high ozone days occur in the summer when there is plenty of sunlight to drive the photochemistry, warm temperatures accelerate some of the reactions, and temperature inversions often limit vertical mixing. After taking the lead in 1999 and 2000, Houston has dropped back below Los Angeles in the number of annual exceedences. The annual variability is caused primarily by meteorology.

19.2 The Effects of Climate and Topography on Air Pollution  Air pollution levels in a region are affected by a number of factors, among them:  Temperature  Sunlight  Wind  Other climate factors  They are also affected by the topography.

FIGURE 05a: Temperature profiles: normal pattern

FIGURE 05b: Temperature profiles: temperature inversion

The Health Effects of Air Pollution FIGURE 6: Urban air pollution and incidence of emphysema in Winnipeg and St. Louis

Effects on Plants and Nonhuman Animals FIGURE 7: Trees killed by acid deposition in Pisgah Nation Forest, North Carolina © Jerry Whaley/age fotostock

19.5 Noise: The Forgotten Pollutant  Sound is characterized by loudness (measured in decibels) and pitch (how high or low it is).

Indoor Air Pollution FIGURE 14: Radon protection