Clean Air Quality
Table of Contents | Executive Summary | Air Quality | Voluntary Measures | Appendix/Acknowledgements

AIR QUALITY IN THE TRI-VALLEY AREA:  CAUSES, EFFECTS AND CURRENT STATUS

Introduction

Breathing air pollution such as ozone (a primary ingredient in urban smog), particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead can have numerous effects on human health, including respiratory problems, hospitalization for heart or lung disease, and even premature death. Some can also have effects on aquatic life, vegetation, and animals. The U.S. Environmental Protection Agency and the California Air Resources Board have established National and State Ambient Air Quality Standards for these pollutants to protect human health and our ecology. The primary pollutants affecting air quality in the Bay Area are ground-level ozone and particulate matter.

The Tri-Valley Area, in particular, is at high risk because most violations of the ozone air quality standards in the Bay Area occur at the Livermore monitoring station. Violations of the particulate matter standard are also seen at the Livermore station. The Tri-Valley Area is now a major residential and employment center in its own right, in addition to being downwind of several major freeways and industrial areas. The mountains surrounding the Tri-Valley Area tend to trap pollutants so when weather conditions are right, such as very hot summer days or very cold winter nights, the emissions from vehicles and other activities create unhealthful air that often exceeds the standards.

Why does the Livermore Valley have a tendency to have higher air pollution levels than the surrounding areas?

The Livermore Valley is a sheltered, inland valley with 1,000 to 1,500 foot hills on its eastern and western slopes and 3,000 to 3,500 foot high mountains on its south side. Due to its topography, the potential for elevated pollution levels increases when the air is stagnant and the temperatures are high. Winds from the west pick up ozone precursor pollutants as they move across the cities around the San Francisco Bay and carry them into the Livermore Valley. Locally generated emissions, added to these pollutants, are transformed into ozone during the hot, sunny days that are common to this area. When the area is under a high-pressure system, light winds combined with an inversion, act to trap the pollutants within the valley, resulting in ozone levels above national standards. Air quality, overall, has improved in the Livermore Valley with excesses of the one-hour federal ozone standard declining from over 50 days in the late 1960's to one or two days per year in recent years.

During the winter months in the Livermore Valley, strong high-pressure systems sometimes develop, leading to the formation of surface-based temperature inversions. Pollutants such as particulate matter (PM)-from motor vehicles, fireplaces and agricultural burning-can build up and become trapped close to the ground. PM concentrations are highest at night and in the early morning hours, especially on clear, calm, cold nights.

OZONE

Ozone (O3) is a gas composed of three oxygen atoms. It is not usually emitted directly into the air, but is created at ground level by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of heat and sunlight.

VOC + NOx + Heat + Sunlight = Ozone

Ozone has the same chemical structure whether it occurs miles above the earth or at ground level and can be "good" or "bad," depending on its location in the atmosphere.  "Good" ozone occurs naturally in the stratosphere approximately 10 to 30 miles above the earth's surface and forms a layer that protects life on earth from the sun's harmful rays.  In the earth's lower atmosphere, ground-level ozone is considered "bad."  Motor vehicle exhaust and industrial emissions, combustion, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC that form ozone.  Sunlight, hot weather and low wind cause ground-level ozone to form in harmful concentrations in the air. As a result, it is known as a summertime air pollutant.  Many urban areas tend to have high levels of "bad" ozone, but even rural areas are also subject to increased ozone levels because wind carries ozone, and pollutants that form it, hundreds of miles away from their original sources. 

The pie charts in Figure 1 below show the breakdown of NOx and VOC emissions for Alameda County. Note that the vast majority of NOx emissions (91%) come from mobile sources.  On-road mobile sources include cars, trucks, and buses.  Off-road mobile sources include construction equipment, boats and aircraft.  For VOC, the majority of emissions also come from mobile sources. Industry also contributes a significant portion of VOC emissions.

As Figure 2 illustrates, the number of excesses of the Federal 1-Hour Ozone Standard in the Bay Area is decreasing.  An exceedance occurs when ozone levels are above the standard for more than 60 consecutive minutes on any day at any monitoring station.  Most of these excesses in the Bay Area occur in Livermore.  This is due in part to Livermore's location (downwind from several major freeways and industry).  It is also due to the very warm weather found in the Tri-Valley region. Ozone is formed on very hot summer days. Typically, these are days when the temperature is near or exceeding 100 degrees in the Tri-Valley Area.

Effects of Ground-Level Ozone on Human Health and the Environment:

Health Problems - even at low levels, ozone can adversely affect everyone.

• Ozone can irritate lung airways and cause inflammation much like a sunburn.  Other symptoms include wheezing, coughing, pain when taking a deep breath, and breathing difficulties during exercise or outdoor activities.  People with respiratory problems are most vulnerable, but even healthy people that are active outdoors can be affected when ozone levels are high.
  
  

• Repeated exposure to ozone pollution for several months may cause permanent lung damage.  Anyone who spends time outdoors in the summer is at risk, particularly children and other people who are active outdoors.
  
  

• Even at very low levels, ground-level ozone triggers a variety of health problems including aggravated asthma, reduced lung capacity, and increased susceptibility to respiratory illnesses like pneumonia and bronchitis.

Plant and Ecosystem Damage

• Ground-level ozone interferes with the ability of plants to produce and store food, which makes them more susceptible to disease, insects, other pollutants, and harsh weather.
  
  

• Ozone damages the leaves of trees and other plants, ruining the appearance of cities, national parks, and recreation areas.
  
  

• Ozone reduces crop and forest yields and increases plant vulnerability to disease, pests, and harsh weather.

PARTICULATE MATTER

Particulate matter, or PM, is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets.  Particles can be suspended in the air for long periods of time.  Some particles are large or dark enough to be seen as soot or smoke.  Others are so small that individually they can only be detected with an electron microscope.  Fine particulate matter is of greatest concern because it can bypass the body's natural filtration systems and lodge deep in the lungs.

Some particles are directly emitted into the air.  They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood.  Other particles may be formed in the air from the chemical change of gases.  They are indirectly formed when gases from burning fuels react with sunlight and water vapor.   These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.  The pie chart in Figure 3 shows the contribution of particulate emissions in Alameda County.

As Figure 4 below illustrates, the number of excesses of the State Particulate Matter Standard (PM10) is holding steady at 2-4 per year for the Tri-Valley Area.  "PM 10" stands for "Particulate Matter less than 10 microns in size."  Ten microns is roughly one-tenth the diameter of a human hair.  These very small particles can penetrate deeply into lung tissue where they can adversely affect our health.  Excesses of this standard occur not only in the Tri-Valley Area, but also at other inland valley locations in the Bay Area.  The mountains in these areas tend to trap the pollutants.  Strong inversions also trap pollutants near the surface.  While ozone excesses occur on hot summer days, particulate excesses occur in the winter on cold, still days.  Days with strong inversions are conducive to high levels of pollution.  Strong inversions occur in the winter, and trap the pollutants near the ground, where we breathe them.  These strong inversions can last several days at a time.

Effects of Particulate Matter on Human Health and the Environment:

Health Problems

Many scientific studies have linked breathing PM to a series of significant health problems, including:

• aggravated asthma

• increased respiratory symptoms like coughing and difficult or painful breathing

• chronic bronchitis

• decreased lung function

• premature death

Visibility Impairment

PM is the major cause of reduced visibility (haze) in parts of the United States, including many of our national parks.

Atmospheric Deposition

Particles can be carried over long distances by wind and then settle on ground or water.  The effects of this settling include:

• making lakes and streams acidic

• changing the nutrient balance in coastal waters and large river basins

• depleting the nutrients in soil

• damaging sensitive forests and farm crops

• affecting the diversity of ecosystems

Aesthetic Damage

Soot, a type of PM, stains and damages stone and other materials, including culturally important objects such as monuments and statues.

GROWTH AND AIR QUALITY

Air quality in the Bay Area and the Tri-Valley Area has improved greatly in the past 30 years, thanks to aggressive control programs adopted by government agencies and the voluntary efforts of the area's citizens.  However, still more needs to be done to achieve all the ambient air quality standards.  Maintenance of these standards will be even more difficult in light of the anticipated population growth and the resulting pollution from more vehicles and economic activity.

More people are choosing to live and work in the Tri-Valley area, and more people are commuting through this area on their way to work.  This means more cars on the road, which means our total vehicles miles traveled is increasing.  We are driving our cars further and further each year.  Many people have daily commutes that are as long as two hours.  As Figures 5 and 6 indicate, the population and vehicle miles traveled for the Tri-Valley Area have increased substantially during the past several years, and are projected to continue to grow.

Therefore, even though the emissions of individual cars will continue to decrease in the years ahead (due to much cleaner engines in newer vehicles), the increase in the total number cars and vehicle miles traveled will make achieving and maintaining the standards very challenging. Also, because much of the PM10 emissions from motor vehicles come from road dust kicked up as the vehicles travel rather than out of the tailpipe, increases in VMT will result in increased emissions of PM10, regardless of cleaner engine technology. On a positive note, transportation and transit improvements planned for the I-580 and I-680 corridors, such as HOV/Smart lanes and expanded rail and bus service, will help to address the air quality in the long term.

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