State of the Air Report

http://www.stateoftheair.org/ provides a map to your state and city's air quality!
San Francisco got an 'A' grade for ozone, so ozone is not the cause for my asthma.
However San Francisco got an 'F' for particle pollution... so that may be a contributing factor.

http://www.stateoftheair.org/2008/states/california/particle-pollution.html

I need however a breakdown of how that value was calculated.

Air Pollution Basics

Two types of air pollution are especially dangerous to breathe—ozone (smog) and particle pollution (soot). The American Lung Association State of the Air 2008 report ranks cities most affected by ozone pollution, short-term and year-round particle pollution.

Ozone (O3)

• Ozone is an invisible gas that is formed most often by a reaction of sunlight and vapors emitted when fuel is burned by cars and trucks, factories, power plants and other sources. Ozone usually peaks in the summer months, from May through October, when temperatures are highest and sunlight is strongest.
• Ozone reacts chemically ("oxidizes") with internal body tissues with which it comes in contact. Like sunburn irritates the skin, it especially irritates the respiratory tract, and can cause health problems the day you breathe in high levels of smog or after long-term exposure.
• Ozone is particularly dangerous for people with asthma and other chronic lung diseases, senior citizens, children and teens. It can cause asthma attacks, coughing and wheezing, shortness of breath, chest pain when inhaling deeply, and even premature death. Breathing high levels of ozone repeatedly over the long term may also lead to impaired lung function, inflamed lung lining, and increased breathing problems.

Particle Pollution

• Particle pollution is the most dangerous of the widespread outdoor air pollutants. It is typically made up of ash, soot, diesel exhaust, chemicals, metals and aerosols. Particle levels can spike dangerously for hours to weeks on end (short-term) or reach high levels for most of the year (year-round).
• Breathing particle pollution can kill. Breathing particle pollution year-round can shorten life by one to three years. It triggers heart attacks, strokes, irregular heartbeats, and causes lung cancer and premature births. Particle pollution harms people in many ways, even when the particle levels are very low. Particle pollution worsens serious respiratory disorders, including asthma and causes wheezing and coughing.
• In the eastern U.S., many particles come from power plants that burn coal to produce electricity. In the western U.S., particles come from diesel buses, trucks and heavy equipment, agriculture and wood burning.
• The body’s natural defenses help to cough or sneeze larger particles out of our bodies. But smaller particles can be so tiny that they can become lodged deep in the lungs and cause major damage, or pass from the lungs into the blood stream and then throughout the rest of the body.