It looks like the Tar fire in the mountains above Fresno is the most likely suspect for the source of the smoke in the Valley. The California Department of Forestry & Fire Protection is reporting the fire has burned 5,174 acres in a naturally occuring asbestos area. Firefighters have had to be removed from the area and equipment decontaminated. Two people have been injured in the fire which started 5:34 p.m. Friday.
Smoke is made up of a complex mixture of gases and fine particles produced when wood and other organic matter burn. The biggest health threat from smoke comes from fine particles. These microscopic particles can get into your eyes and respiratory system, where they can cause health problems such as burning eyes, runny nose, and can worsen illnesses such as bronchitis. Fine particles also can aggravate chronic heart and lung diseases - and even are linked to premature deaths in people with these conditions.
If you have heart or lung disease, such as congestive heart failure, angina, chronic obstructive pulmonary disease, emphysema or asthma, you may experience health effects earlier and at lower smoke levels than healthy people.
Older adults are more likely to be affected by smoke, possibly because they are more likely to have heart or lung diseases than younger people. Children also are more susceptible to smoke for several reasons: their respiratory systems are still developing; they breathe more air (and air pollution) per pound of body weight than adults; and they're more likely to be active outdoors.