Health Effects

Particulate matter, also called PM or soot, consists of microscopically small solid particles or liquid droplets suspended in the air. The smaller the particles, the deeper they can penetrate into the respiratory system and the more hazardous they are to breathe.

Recent studies indicate that PM can have the following effects on our bodies:

• PM pollution can cause lung irritation, which leads to increased permeability in lung tissue.
• PM aggravates the severity of chronic lung diseases, causing rapid loss of airway function.
• PM causes inflammation of lung tissue, resulting in the release of chemicals that can impact heart function.
• PM causes changes in blood chemistry that can result in clots that may lead to heart attacks.
• PM can increase susceptibility to viral and bacterial pathogens leading to pneumonia in vulnerable persons who are unable to clear these infections.

The smaller-sized particles - those 2.5 micrometers or less in diameter, called PM2.5 - are of greatest health concern because they can pass through the nose and throat and be absorbed deep inside the lungs. PM 2.5 are sometimes called "fine" particles, and they are about 1/28th the diameter of a human hair or smaller.

In the Bay Area, wood burning accounts for about one-third of the airborne PM in the winter months. PM in wood smoke from the estimated 1.4 million fireplaces and wood stoves in the Bay Area has been a health concern for many years.

PM Health Studies

Since the 1980s, many scientific studies have been published that correlate exposure to wood smoke and PM with serious public health effects, such as higher instances of asthma, decreased lung function in children, increased hospital admissions, and elevated mortality rates.