PM2.5 — The Tiny Villain of Air Pollution

Winter air pollution has always been a problem in the Bay Area on nights when the air is cold and still. Concentrated air contaminants, chiefly from automobiles and woodburning, accumulate and remain trapped close to the ground in the "breathing layer." This unhealthy condition continues often until midmorning when the sun heats the earth surface, causing the pollutant-laden layer to expand and the contaminants to disperse. The problem is especially bad for people who live in the thousands of small dips and valleys of our region where pollutants roll down hill and can stay trapped much longer than in flatter neighborhoods.

The prime offenders in our winter air are carbon monoxide and respirable particulate matter (PM10). And while the Air District has been monitoring these pollutants throughout its nine-county jurisdiction, violations of the health standards have been rare in recent years.

But all of that is about to change this winter with the introduction of monitoring for what is probably the deadliest winter pollutant: PM2.5, ultra-fine particles of various substances so small that they cannot be seen and may stay airborne for weeks. When inhaled PM2.5 can settle in a person's lung tissue, remaining there indefinitely.

Epidemiologists (scientists who study diseases and their spread) have correlated high PM2.5 concentrations to increases of hospital admissions and rises in the death rate among our aged population. Other PM2.5 studies implicate infant mortality and premature births. PM2.5 is also of particular concern to the growing segment of our urban population with chronic asthma and other respiratory problems.

If PM2.5 poses such a health threat, why is it only being tracked now, since it's presumably been around forever?

True, PM2.5 has been around since before the first caveman's fire, even the first volcano. But because the particles are so very very small, their quantitative contribution to air pollution could not be measured. Now the technology for this task is available and with it a new health standard has been instituted by the Environmental Protection Agency.

How small is small? In the case of PM2.5 it's microscopic. PM2.5 is comprised of particles so small they can pass through a filter with 2.5 micron pores. That's about 1/28 the diameter of a strand of human hair. And the bulk of PM2.5 particles are half that size and smaller! The particles are in fact so small that they can not generally be produced by physical grinding--unlike, say, the fine particles of rubber tire ground away by road surfaces, an identifiable fraction of PM10 pollution.

At this date, only a few Air Districts in the country are equipped for reporting on PM2.5. The Bay Area Air District joins the Los Angeles District in introducing PM2.5 monitoring in the winter of 2002/03

What can an individual do to keep PM2.5 pollution to a minimum?

As mentioned above, PM2.5 pollution has two major sources — woodburning appliances and automobile engines — both are combustion sources. During the cold weather months, and especially whenever the Air District issues a "SPARE THE AIR TONIGHT" advisory, Bay Area residents should:

o  reduce their driving to a minimum or take public transit

o  refrain from burning wood in a fireplace or older woodstove.

A suggestion for those who use fireplaces or woodstoves for heat.

Logs burning on the hearth may be visually appealing, but they provide little heat inside a home and they provide irritation and health hazards to the neighborhood. PM2.5 particles are so minuscule that the smaller ones easily invade even the best weatherproofed homes nearby. Smoke from fireplaces and stoves is stinky and an annoyance to many who may be reticent to let you know how much your smoke is bothering them. If you must burn wood as a heating fuel, BURN IT RIGHT! A call to 1-800-HELP AIR will allow you to order a free copy of the Woodburning Handbook.

This colorful, well illustrated booklet not only can educate you about winter pollution, but will also inform you on cleaner burning technologies, such as pellet stoves, EPA-certified stoves and fireplace inserts, or natural gas inserts that look as natural as a traditional fireplace — without the expense, the loss of heat or the maintenance. The Woodburning Handbook may also be read online at www.sparetheair.org.

PM2.5 — The Tiny Villain of Air Pollution

Winter air pollution has always been a problem in the Bay Area on nights when the air is cold and still. Concentrated air contaminants, chiefly from automobiles and woodburning, accumulate and remain trapped close to the ground in the "breathing layer." This unhealthy condition continues often until midmorning when the sun heats the earth surface, causing the pollutant-laden layer to expand and the contaminants to disperse.

The prime offenders in our winter air are carbon monoxide and respirable particulate matter (PM10). And while the Air District has been monitoring these pollutants throughout its nine-county jurisdiction, violations of the health standards have been rare in recent years.

But all of that is about to change this winter with the introduction of monitoring for what is probably the deadliest winter pollutant: PM2.5, ultra-fine particles of various substances so small that they cannot be seen and may stay airborne for weeks. When inhaled PM2.5 can settle in a person's lung tissue, remaining there indefinitely.

Epidemiologists (scientists who study diseases and their spread) have correlated high PM2.5 concentrations to increases of hospital admissions and rises in the death rate among our aged population. PM2.5 is also of particular concern to the growing segment of our urban population with chronic asthma and other respiratory problems.

If PM2.5 poses such a health threat, why is it only being tracked now, since it's presumably been around forever?

True, PM2.5 has been around since before the first caveman's fire, even the first volcano. But because the particles are so very very small, their quantitative contribution to air pollution could not be measured. Now the technology for this task is available and with it a new health standard has been instituted by the Environmental Protection Agency.

What can an individual do to keep PM2.5 pollution to a minimum?

As mentioned above, PM2.5 pollution has two major sources — woodburning appliances and automobile engines — both are combustion sources. During the cold weather months, and especially whenever the Air District issues a "SPARE THE AIR TONIGHT" advisory, Bay Area residents should:

o  reduce their driving to a minimum or take public transit

o  refrain from burning wood in a fireplace or older woodstove.

A suggestion for those who use fireplaces or woodstoves for heat.

Logs burning on the hearth may be visually appealing, but they provide little heat inside a home and they provide irritation and health hazards to the neighborhood. PM2.5 particles are so minuscule that the smaller ones easily invade even the best weatherproofed homes nearby. Smoke from fireplaces and stoves is stinky and an annoyance to many who may be reticent to let you know how much your smoke is bothering them. If you must burn wood as a heating fuel, BURN IT RIGHT! A call to 1-800-HELP AIR will allow you to order a free copy of the Woodburning Handbook.

This colorful, well illustrated booklet not only can educate you about winter pollution, but will also inform you on cleaner burning technologies, such as pellet stoves, EPA-certified stoves and fireplace inserts, or natural gas inserts that look as natural as a traditional fireplace — without the expense, the loss of heat or the maintenance. The Woodburning Handbook may also be read online at www.sparetheair.org.