Environmental Quality Branch

PARTICULATES

Fine Particulates: What They Are and How They Affect Us

Last Updated: February 2007

Introduction

A layer of haze blankets a busy city on a hot summer day, reducing the nearby mountains to a blurry outline. A thin string of smoke trails out of a chimney on a cold, calm winter night. Huge clouds of smoke billow from a raging forest fire.

What do these images have in common? Tiny particles, called "fine particulates." Soiling the air, spoiling the view and taking our breath away. Literally.

Ever since our early ancestors gathered around their first fire, humans have been releasing fine particulates into the air. Only recently have scientists discovered the bad news: fine particulates are so small that they can easily be inhaled into the deepest reaches of our lungs, causing serious lung and heart disease. Fine particulates are also a visual blight, capable of reducing visibility so much that beautiful views are blotted out, and road and air travel is made difficult.

Hold on a moment! Human beings have managed to live with fine particulates for thousands of years, haven't they? Why all the fuss now?

Well, the truth is that lung disease has always been a major health problem throughout the world, and a leading cause of death. Just as bacteria were causing serious illness long before they were discovered, it's likely that fine particulates have always contributed to lung disease. We just didn't know it.

Recent studies have found that fine particulates at current levels can pose a greater danger to our health than the better-known kinds of air pollution, such as smog, sulphur dioxide and carbon monoxide. Fine particulates are linked with all sorts of health problems — from a runny nose and coughing, to bronchitis, emphysema, asthma and even death.

In fact, new research in the United States suggests that fine particulates are responsible for tens of thousands of deaths in that country each year. Closer to home, a 1995 study (PDF: 196 KB / 126 pages) for the Provincial Health Officer has found good evidence that, in B.C., short-term exposure to fine particulates is associated with increases in deaths from lung and heart disease. Breathing in fine particulates for a short time is also associated with more lung, and probably heart, disease — and more hospitalizations for treatment.

The contribution of fine particulates to reducing visibility has also become an important issue in our province. Visibility has been cited as a major air quality problem by residents in the Lower Mainland. People in B.C.'s more rural areas have expressed concern about the smoke produced by various wood-burning activities, including prescribed forestry (slash) burning and the disposal of sawmill wood residue in beehive burners. Land clearing and construction fires, backyard burning and wood stoves are other sources of smoke — not to mention fine particulates.

It's time to clear the air!

Besides taking action to control fine particulates, we need to understand the nature of the problem.
This fact sheet will introduce you to fine particulates: what they are, where they come from and why they are so effective at impairing breathing and visibility.
It will also explain what the government is doing to
get fine particulates out of the air, and how you can become part of the solution.

What are Fine Particulates?

Fine particulates may sound like a heavy scientific expression, but it breaks down into simple concepts. Particulates are tiny solid or liquid particles that come in many shapes and sizes, and from many different sources. They are also called particulate matter, or PM for short.

Fine particulates are 10 micrometres or less in diameter (PM10). A micrometre is a millionth of a metre, so PM10 is roughly the same size as bacteria — and like bacteria, PM10 is invisible to the naked eye and small enough to be breathed into our lungs.

Not all PM10 is created equal. It can be composed of very small particulates of about 0.1 to 0.2 micrometres in diameter, like you'd find in automobile exhaust or fireplace emissions. It can also include particulates at least 10 times this size, like you'd find in sea salt spray or road dust.

To simplify things, we often refer to a fine and coarse fraction of PM10, since they generally differ in chemical composition source and behavior in the air:

• The fine fraction (PM2.5) contains particulates 2.5 micrometres or smaller. This fraction is most often generated by combustion processes and by chemical reactions taking place in the air.
  
  
• The coarse fraction contains particulates greater than 2.5 micrometres. This is the size most closely associated with natural sources.

Good Things Don't Always Come in Small Packages

From our lungs' point of view, bigger particulates are less harmful. Because of their weight, particulates larger than 10 micrometres settle to the ground quickly. If we do inhale them, they tend to collect in our throat and nose, and are eliminated from our body by sneezing, coughing, nose blowing or through the digestive system.

Particulates in the coarse fraction of PM10 are removed in the upper respiratory system. In other words, they don't travel very far into our lungs. They contain materials common to the earth's crust and the ocean, reflecting the fact that natural sources such as windblown dust and sea salt spray are big contributors to the coarse fraction.

Vegetation is another large natural source. Human activities that involve grinding or pulverizing, such as mining, quarrying and cement manufacturing, are also important. These particulates don't stay in the air too long, settling to the ground within a matter of a few hours to a few days.

In contrast, particulates in the fine fraction (PM2.5) can remain in the air for days to weeks. They can penetrate especially deep into our lungs, collecting in the tiny air sacs (called "alveoli") where oxygen enters the bloodstream. As a result, they can cause breathing difficulties and sometimes permanent lung damage.

A number of potentially harmful substances have been found in PM2.5:

• Sulphates produced from sulphur dioxide emissions are acidic in nature, and may react directly with our lungs.
  
  
• Elemental carbon produced during wood and engine combustion can pick up cancer-causing chemicals like benzo(a)pyrene and give them a free ride into our lungs.
  
  
• Hundreds of organic carbon compounds, besides benzo(a)pyrene, have been identified in exhaust from vehicles, combustion processes and even meat-cooking operations.
  
• Several studies have shown that toxic trace metals such as lead, cadmium and nickel are more concentrated in PM2.5 than in bigger particulates.

Sources of Fine Particulates in British Columbia

Fine particulates are produced from a wide variety of sources, both natural and human-caused, large and small. Some are released directly into the air, and are called "primary particulates." Other fine particulates are formed from physical and chemical reactions mainly involving gases emitted into the air. These are called "secondary particulates."

In the Lower Fraser Valley, the largest sources of primary PM10 are diesel vehicles (trucks and buses), bulk shipping terminals, the wood products industry, gasoline vehicles and road dust.

Diesel and gasoline vehicles are thought to be the major sources of PM2.5. In the rest of B.C., prescribed forestry burning and wildfires are among the major contributors of both primary PM10 and PM2.5 emissions.

In many communities, beehive burners have been identified as major sources of PM10 emissions. Not only are these burners inefficient, but in most cases they're spewing particulates into the air 24 hours a day, regardless of the weather conditions. Also, wintertime emissions from wood stoves and fireplaces are very significant, as these sources produce very fine particulates right under our nose.

At present, we don't know how much secondary particulates — sulphates, nitrates and organic carbon compounds — contribute to PM10 levels in B.C.. However, we do know quite a bit about the gases they come from (the precursors) as, shown it the table below.

We also know that secondary PM10 is found mostly in the fine fraction, and its potential effects of visibility are significant. For instance, sulphates are responsible for most visibility problems in Eastern Canada and the United States, while nitrates are important in western cities such as Denver and Los Angeles.

There are also many small sources of fine particulates that we come in contact with every day. Hamburgers sizzling on a smoky grill. Motor vehicles kicking up dust, coughing out soot and hundreds of different organic carbon compounds in their exhaust. Fireplaces. Wood stoves. Cigarette smoke. All these particulates are not being emitted from a stack 100 metres high and 100 kilometres away. They're being released in our streets, our backyards, our living rooms ... and they are finding their way into our lungs.

Fine Particulates Are Not Fine for People

At current levels, fine particulates are now considered the worst kind of air pollution problem in B.C.. It is more hazardous than ground-level ozone (the key, unhealthy ingredient of smog), and all other outdoor air pollutants. That's the conclusion of two reports in 1993 and 1995, by Dr. Sverre Vedal of the University of British Columbia.*

The findings are quite alarming. Exposure to high levels of fine particulates is associated with a significant rise in the number of premature deaths from respiratory and heart disease. It's also linked with more emergency room visits and hospitalizations.

Fine particulate air pollution triggers many kinds of respiratory illnesses, including asthma, bronchitis, pneumonia and emphysema. Senior citizens, infants and people who already have lung, asthmatic or heart problems are most at risk, but healthy younger adults and children can also be affected. The connection between asthma and fine particulates is noteworthy. Over 1.2 million Canadians suffer from this condition, and asthma is the most common cause of medical emergencies in children.

Scientists now have established that fine particulate pollution makes "sick people sicker" — even enough to kill them. What scientists still don't know is if it actually causes new cases of lung and heart disease.

*1995 Report: Health Effects of Inhalable Particles: Implications for British Columbia   PDF: 196 KB / 126 pages

*1993 Report: Health Effects of Wood Smoke: A Report to the Provincial Health Officer of British Columbia  Contact the Provincial Health Officer, at (250) 952-0876.

Where Did the View Go?

Fine particulates have another unwelcome talent: the smaller ones are effective at getting in the way of light reflected from distant objects to your eye. They can both absorb light, or reflect (scatter) it in all sorts of directions. The net effect is that these particulates can blot out the view, making it difficult for residents and tourists alike to enjoy the scenery, or even travel by road or air.

What types of particulates are mostly to blame? Those of approximately 0.1 to 1 micrometres in diameter are about the same size as the wavelength of visible light. This makes them perfect for interfering with light, which means you can't see as far or as well.

Soot is good at absorbing light, while secondary particulates such as sulphates and nitrates are good at scattering light. This is especially true under conditions of higher humidity, when their scattering ability is enhanced by water vapour in the air.

An entire region may experience reduced visibility due to large sources such as forest fires. Just ask those people living in the interior of B.C. during the summer of 1994 when a number of major fires raged through the area.

Secondary particulates from many different sources are believed to be responsible for visibility problems in the Lower Fraser Valley. In your own backyard (so to speak), fireplaces, wood stoves, and backyard burning can create a lot of smoke for you and your neighbours, especially when the winds are calm and the air is not mixing very well.

The Government is Working to Reduce Fine Particulates

The Ministry of Environment has moved to control the sources of smoke in B.C., and encourage the use of wood and leafy residue as a resource. It has done so by setting regulations, along with taking nonregulatory actions — such as broad programs, technical support and public education. And because motor vehicles are a major source of fine particulates, the ministry has brought in measures to control their emissions, as well.

The B.C. Government has passed the following regulations:

• Open Burning Smoke Control Regulation (April 1993, amended in 1998 and 2000)
  The Open Burning Smoke Control Regulation is meant to encourage the reduction and reuse of vegetative debris from large outdoor fires which are usually set for land-clearing, construction or forestry operations.
  
  
• Solid Fuel Burning Domestic Appliance Regulation (August 1994)
  The Solid Fuel Burning Domestic Appliance Regulation specifies particulate emission limits, and labeling and testing requirements, for new solid-fuel (wood) stoves, fireplace inserts and factory-built fireplaces manufactured after November 1, 1994.
  
  
• Wood Residue Burner and Incinerator Regulation (December 1995, includes amendments up to 2004)
  Under this regulation, wood residue (beehive and silo) burners in populated areas (Tier 1) are to be shut down by the end of 2007. Of the original 80 Tier 1 burners, 73 have now been shut down. Eliminating these inefficient burners, which frequently cast palls of smoke over many valleys, will lead to cleaner air in many regions.

To make it easier for municipalities to pass their own "anti-smoke" bylaw, the ministry created a model bylaw on (back)yard burning in December 1997. Municipalities can use this model to draft a specific bylaw to limit or prohibit backyard burning. See the Model Municipal Bylaw for Regulating Backyard Burning (PDF: 131 KB / 18 pages).

With respect to nonregulatory approaches, the Environmental Quality Branch has given educational and technical support to municipalities and the public — on proper burning techniques, wood stoves, backyard burning restrictions or bans, and composting.

In addition, the provincial government has provided $300,000 for an ethanol development program, called Ethanol BC. This project will support the growth of commercially healthy technologies for producing ethanol, a fuel made from softwood residue. The Canadian Petroleum Products Institute has also committed $100,000 over five years.

The Ministry of Environment took part in developing the Canada-wide Standards for Particulate Matter and Ozone in July 2000. By setting targets for acceptable air quality, and agreeing to a set of joint initial actions, B.C. and the rest of Canada are taking an important step towards reducing the risk that fine particulates (and ground-level ozone) pose to human health.

To reduce fine particulate pollution in the Lower Fraser Valley, the B.C. Government launched the AirCare ON ROAD (ACOR) testing program in 1999. ACOR targets heavy-duty, diesel trucks and buses. Two mobile teams test the emissions of heavy-duty, commercial diesel vehicles. Vehicles that fail the emissions test must be repaired and re-inspected before they can qualify for insurance renewal.

B.C.'s tailpipe standards for new vehicles (see the regulations on our Vehicle Emissions website), the AirCare vehicle-emission testing program, and the older-vehicle "Scrap-It" program are all working to stop the production of secondary particulates. These programs take a large chunk out of our vehicle emissions. As a result, they cut down on the potential amount of precursor gases flowing into our airspace — those gases that end up producing fine particulates after undergoing a chemical transformation in the air.

How You Can Help

Government laws and programs are not enough. We need to take personal responsibility for reducing fine particulates "right under our nose" — the emissions we create through our own lifestyle choices, such as driving our car and using an old, smoky wood stove.

Here are some important tips on how you can help put a lid on smoke and vehicle exhaust, two key sources of fine particulates in B.C.:

• Break the automobile addiction! Use public transit or become part of a carpool. Better yet, ride your bike, cycle or use your feet. Even if each of us leaves our car at home just once a week, the reduction in emissions will be substantial. Less driving also means less road dust, which is produced when vehicles move over roads.
  
  
• Ensure your car is well-tuned for minimum emissions and fixed to prevent oil being burned in the engine and a "smoke screen" created in your wake!
  
  
• When buying a new car, choose one that's fuel-efficient and has low emissions.
  
  
• Stop smoking out your neighbours! Instead of burning your leaves and clippings, start a backyard compost. Also, don't burn your garbage (e.g., plastics, paper and cardboard). It releases all sorts of nasty pollutants into the air.
  
  
• Buy an efficient, certified wood stove that's just the right size for your home. Install and operate it correctly. Overloading your stove or starving the fire of air can release too much smoke.
  
  
• When you burn wood, avoid wet or green wood which will cause lots of smoke. Wood should be properly seasoned in a dry place for at least six months, and split. Avoid wood that is treated, painted, or laden with saltwater, as it can release potentially toxic substances when burned.
  
  
• Think of your neighbour's health, not to mention your own. If you simply have to burn, don't burn when the smoke will linger in an area, such as on clear and calm nights. Be aware of the "no-burn" periods in your community, and don't bend the rules!

For More Information:

Environmental Quality Branch
Ministry of Environment
Government of British Columbia

PO Box 9341, Stn Prov Govt
Victoria, British Columbia
Canada V8W 9M1
phone: (250) 387-9932
fax: (250) 356-7197
http://www.env.gov.bc.ca/air

Other Agencies to Contact:

Ministry of Health Services
Public Health Protection

Greater Vancouver Regional District

Photos courtesy of the British Columbia Lung Association, Environment Canada, and the B.C. Provincial Emergency Program