What prompted me to write this blog was a recent trip to the rapidly growing Asian city of Kuala Lumpur, the capital of Malaysia. The name of the city is not that important however because this blog applies to other fast growing cities and many long established cities around the globe. I was last in Kuala Lumpur around 12 years ago. Back then the government had big plans to convert what was a relatively undeveloped city into a metropolis, the equal of anything in the developed world. Twelve years on and judging from the large number of skyscrapers, hotels, new roads, apartment blocks, shopping centres and expanded railway system, the government could with some justification state “Mission accomplished”, to paraphrase George W. Bush.
But the breakneck speed of development has come at a price. Pedestrian crossings are ignored and the traffic so congested crossing a road at peak hour is not worth the risk. The constant noise. Footpaths with cracked and uneven surfaces. Inadequate gutters and drains and strange smells coming from storm water. For me however, the most troubling aspect of all this “development” was the quality of the air. You can wear earplugs to keep out the noise. You can get used to taking your life in your hands every time you cross the road, and you can learn to take special care when walking on cracked and uneven pavements. However there is really very little you can do about the quality of the air you breathe – we have to breathe to live!
While the poor quality of the air was obvious at street level, it was much more dramatic looking down from the aircraft as my wife and I flew into the city. All we could see was a dirty opaque haze, enveloping the city. As we descended into the haze to land I began to wonder – Where did the haze come from? What is in polluted city air? And more importantly: Is it safe and what does it do to our bodies? Can it increase the risk of disease? And, if it does, which diseases? I made a mental note to look into the topic when I arrived back in Australia. We know quite a lot about air pollution, because many cities around the world have been monitoring both the levels of air pollution and the types of pollutants for many years. Sadly, we know far less about the long-term health effects of air pollution.
Air pollution is made up of volatile (i.e. gaseous material) and particulate matter. The gaseous material may be invisible and the main gases include:
• Nitrogen dioxide (formed from burning fossil fuels or wood);
• Ozone (formed from the interaction of oxygen in the air with nitrogen dioxide and hydrocarbons from fossil fuels);
• Sulphur dioxide (formed from burning fossil fuels, smelting, and paper production);
• Carbon monoxide and carbon dioxide (formed by burning fossil fuels);
• Methane (formed by the decomposition of plant matter and produced by livestock).
Of course, many other gaseous pollutants are released as a consequence of a whole host of industrial activities and it is next to impossible to identify them all.
The particulate matter in air pollution is just as complex. Some is released into the atmosphere as a consequence of natural processes like volcanoes, forest fires, pollen and moulds. However, it is the particulate matter coming from human activity that is of concern. Most of this particulate matter comes from burning fossil fuels and other industrial activities. The particulate matter from human activity varies considerably in size. To make it easier to study and model, particulate matter in air pollution is thought to behave like small spheres with varying diameters and masses. Most attention has focused on particulate matter between 1-10 micrometres in size. As a micrometer is one millionth of a metre, these particles are considerably smaller than the head of a pin and can easily find their way into our lungs. Chemical analysis has demonstrated these particles are made up of materials derived from both natural and industrial sources. The natural sources include soil, sand, salt, rocks and dusts. The material originating from industrial activity includes (to name but a few) dust from cement, sand, concrete, plastics, factory exhausts, power plants, wood dust and motor vehicles. The particulate matter from motor vehicles deserves special mention and includes metals, fragments from tyres and brake linings and a wide range of hydrocarbon based compounds coming from the incomplete burning of the fuel. Particulate matter in the air can also interact chemically with the volatile gases discussed above. The end result of all this is a cocktail of chemical substances hanging in the air all of which can find its way into our bodies every time we breathe. And our lungs and sinuses are on the front line.
So, the tiny particles in polluted air are a cocktail of chemical substances. Many are known to be hazardous and there are others yet to be identified whose health effects are unknown. And what of their effects in combination? Given it is almost impossible to avoid air pollution, especially if you live or work in a big city, it is very important to know if the chemical cocktail you are breathing is safe. Sadly, we know surprisingly little about this.
We do know particles in the air – depending on their chemical nature – can increase the risk of disease. It is well known for example that workers in dusty professions like miners, woodworkers and quarry workers have an increased incidence of lung diseases such as asbestosis, black lung and silicosis (1 – 3). But what if the particles also contain lots of adsorbed chemicals, as you could expect to find in polluted cities? Is it a double whammy? No one can really say what this gaseous and particulate matter is doing to humans, particularly in the long term. We do however have some idea of what the effects may be from animal studies. In animals, the particulate matter in air pollution can induce inflammation in the lungs (4). Inflammation has been linked to conditions such as asthma, chronic obstructive lung disease (COPD), heart disease and even cancer and there is evidence particulate matter can cause inflammation in humans (5). There are also an increasing number of medical and scientific reports showing a link between exposure to particulate matter and an increased risk of lung diseases such as asthma, COPD and heart disease (6 – 8).
We really do not know how important air pollution is to the development of degenerative heart and lung conditions. Is it just a few or are significant numbers affected? Because we do not know it is a very important question. The other very important question: What can we do about it? – is also not easy to answer. The only sensible and practical solution is to reduce the emissions produced from the burning of fossil fuels in particular, as these are a major source of both the gaseous and particulate matter in air pollution. In the developed world, there is an increasing awareness pollution is a problem and steps are being taken to reduce the levels of air pollutants. For example, we no longer add lead to petrol in most developed countries and governments around the world are bringing in stricter controls on the emissions from motor vehicles, mining and factories. However, bringing in reforms like these to control pollution takes time and while we wait, all of us who live or work in big cities continue to be exposed.
Promoting Good Health has concerns about the effects of environmental pollutants on our health and wellbeing. If you want to know more about what sorts of environmental chemicals are present in our food and water, their possible impact on our health and how to avoid them or reduce your exposure, please check out our book “The Silent Threat” available through our website. Our new book, “Chemical Pollutants: Known Unknowns”, which looks at our exposure to pollutants released into the environment through industrial activity, will be available through our website within the next few months.
Meanwhile, stay healthy and happy!
(1) Thomas, C. R. and Kelley, T. R.; A brief review of silicosis in the United States. Environ. Health Insights, May 18, 4, 21-26, 2010.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/20523881 
Full article available online at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2879610/pdf/ehi-2010-021.pdf 
(2) Suarthana, E. et al; Coal workers’ pneumoconiosis in the United States: regional differences 40 years after implementation of the 1969 Federal Coal Mine Health and Safety Act. Occup. Environ. Med., Epublication, May 19, 2011.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/21597107 
(3) Jamrozik, E.; de Klerk, N. and Musk, A. W.; Asbestos-related disease. Intern. Med. J., 41 (5), 372-380, 2011.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/21309996 
(4) Happo, M. S. et al; Dose and time dependency of inflammatory responses in the mouse lung to urban air coarse, fine, and ultrafine particles from six European cities. Inhal. Toxicol., 19 (3), 227-246, 2007.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/17365027 
(5) Lin, W. et al; Acute Respiratory Inflammation in Children and Black Carbon in Ambient Air before and during the 2008 Beijing Olympics. Environ. Health Perspect., 119 (10), 1507-1512, 2011.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/21642045 
Full article available online at: http://ehp03.niehs.nih.gov/article/info:doi/10.1289/ehp.1103461 
(6) Andersen, Z. J. et al; Chronic obstructive pulmonary disease and long-term exposure to traffic-related air pollution: a cohort study. Am. J. Respir. Crit. Care Med., 183 (4), 455-461, 2011.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/20870755 
(7) Simkhovich, B. Z.; Kleinman, M. T. and Kloner, R. A.; Particulate air pollution and coronary heart disease. Curr. Opin. Cardiol., 24 (6), 604-609, 2009.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/19696664 
(8) Kelly, F. J. and Fussell, J. C.; Air pollution and airway disease. Clin. Exp. Allergy, 41 (8), 1059-1071, 2011.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/21623970