The health effects of particulate matter in the air can be quite serious.

THANKS to the volcanic ash cloud that hangs over Europe, my wife cannot come back from her work visit to Europe. We know what volcanic ash can do to the engines of aeroplanes. But do these particles have any impact on our health when we breathe them in?

Let’s talk about particles or particulate matter in general, seeing as we have no active volcanoes in Malaysia. (Though we may be affected if a volcano in Indonesia erupts.)

Particulates or fine particles are tiny subsets of solid or liquid materials which are suspended in either a gas (like air) or liquid (like water). When you have particulates suspended in gas, we call it aerosol.

Particulates can either remain solid when suspended, or dissolve in the liquid it is suspended in. Example, salt dissolves in water. But ash will remain as solid in the same water.

Particulates in the air are responsible for causing diseases in the hearts and lungs.

Do these particulates always come from natural disasters like volcanoes?

No. Particulates can come from natural sources or man-made sources.

Natural sources include volcanoes, forest fires (like with the haze), dust storms, and sand storms. Some even come from vegetation, such as when the wind blows fine pollen from the grass. Some even come from the sea.

But humans are also responsible for a lot of the particulates in the atmosphere. Burning, for example, spews a lot of particulates into the air. Industrial plants that let out a lot of effusions from their smoke stacks and diesel engines from trucks and cars also contribute.

It is estimated that 10% of particulate matter in the world’s air come from human activities.

What types of particulates are there floating in the air? How big are they? Can we see them? Do they block out light?

Particulates are usually classified by size. A particulate can be as large as 10 micrometers or as tiny as below 100 nanometers. The latter are called ultrafine particles.

We can definitely see them if they blanket out the sky, e.g. the haze, volcanic ash clouds.

The effects on the climate are very bad. Particulates can affect climate directly by absorbing solar and infrared radiation from the atmosphere. When they absorb too much, a critical point is reached when they start to change from cooling down our atmosphere to heating it.

Indirectly, they cause more condensation of water and increase cloud size.

The eruption of a Russian volcano, for example, in the early 17th century, caused the Russian famine of 1601 to 1603, leading to two million deaths from starvation.

What types of diseases can particulates cause?

The size of the particulate determines where in our respiratory tract the particle will finally rest, and what type of disease it can cause.

The larger the particle, the less effect it has on health. Larger particles are filtered by our nose hairs, then by the cilia in our tracheas, But the smaller ones – less than 10 micrometers – can penetrate to our bronchi and our alveoli (air sacs) in our lungs.

And the really small ones – less than 2.5 micrometers – can penetrate into the barrier between the alveoli sacs and blood. These tiny particles can also lead to plaque deposits in our arteries themselves. This process is called artherosclerosis, where our arteries harden with deposits to become inflexible and inelastic, leading to heart attacks and strokes.

In fact, researchers have found that even short-term exposure to these tiny ultrafine particles can cause significant artherosclerosis.

Now it has been found that really tiny particles of less than 100 nanometers can cross through our cell membranes and be transported into our organs, such as the brain. There are theories that this is one of the causes of Alzheimer’s disease.

It is recorded that particulate pollution is the cause of up to 52,000 deaths per year in the US.

I have heard a lot of bad things about diesel engines. Do they produce particulates?

Yes, and unfortunately, the particulate size produced here (called Diesel Particulate Matter) is the in the range of 100 nanometers, one of the smallest, leading to diseases mentioned above.

The main contaminant here is sulphur dioxide.

Not only that, these particles carry carcinogens, or materials that cause cancer, such as benzopyrene, arsenic, and formaldehyde.

Note that even the shape of the particle can be dangerous. Asbestos particulates are shaped like feathers, and are more dangerous than rounded particulates. They lodge in our lungs and can give rise to asbestosis and the dangerous complication of mesothelioma, a pleural lining cancer.

Note that the diesel exhaust fumes itself can cause irritation to our eyes, nose, throat and lungs, leading to increased asthma attacks.

Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health advice, computers and entertainment. The information contained in this column is for general educational purposes only. Neither The Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. The Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.

Source: Article by DR Y.L.M from the Star Online, 25 April 2010