Health Effects of Pollution
Unfortunately, the air is never pure. Many natural and man-made impurities, called aerosols, are adrift. Suspended particles of a natural origin are sea salt, sand, organic dust, pollen and smoke. Millions of years ago, the natural pollutants of volcanoes and the dust from meteor strikes were enough to poison the air and change the earth’s climate, altering much of life on earth. Many species perished, while others evolved. Today, however, it is the man-made pollution that is of great concern.
The unprecedented population explosion of the modern age brought with it the need for energy. Almost all this energy required around the world is still created by burning fossil fuels. The resulting industry and transport create pollution that makes air in some areas unhealthy. As a consequence, affected people suffer from diseases and die prematurely. Pollution damages agricultural crops, destroys historical monuments, and changes the climate. Relevant terms, such as ‘acid rain’, ‘smog alert’, ‘global warming’ and ‘greenhouse effect’, are common today.
National and international legislation resulted in a reduction of certain pollutants. Since the ban of lead as an additive to automotive fuel, it is no longer a major concern in most cities. Countries agreed to phase out the ‘greenhouse’ gases chlorofluorocarbon (CFC) and halon, but other damaging gases are still increasing in volume, especially in developing countries.
As an interim measure, or perhaps as a token gesture, health authorities issue smog alerts and air-quality warnings to the public. While you can’t stop breathing the filthy air, if you do have lung or heart problems, you can consider precautionary measures, such as the avoidance of strenuous exercise. Some cities experience levels of pollution that even require emergency action plans.
Governments have set certain standards for each pollutant: nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and particulate matter (small suspended particles). They form the basis for an air quality index (AQI). The standards, however, vary around the world, as does the index.
Global air circulation ensures that long-life pollutants spread to all parts of the world. They pose a threat to us when their numbers overwhelm the self-cleaning ability of our respiratory system, or our immune system can’t defend against the intruders.
Breathing isn’t the only way that we are exposed to airborne pollutants and disease-causing microbes. These substances are continually deposited in the soil as dry fallout or precipitation. From the soil they enter the food chain and, ultimately, your body. Overall, your body absorbs more of a particular chemical via intake of food than through breathing. But some harmful substances only exist in gaseous form, and others, such as particulate matter, are only a health risk while airborne.
There is no doubt that airborne impurities bring illness and death. Air pollution disasters, such as London’s ‘killer smog’ in 1952 that killed about 4000 people, are thankfully rare today. Nevertheless, the ill effects are still with us (see table) and even just a few hundred deaths are too many.
The body is like a storage cabinet for toxic substances. A drawer may contain lead or mercury, while another may store modern chemical compounds, such as dioxins or pesticides. Each individual substance accumulates over the years until the drawer is full and eventually overcomes the body’s tolerance. Yet research suggests that an interaction of even low levels of several chemicals can produce Multiple Chemical Sensitivity (MCS).
Chemicals suspended in the air also interact and form new substances. A typical example is the formation of acid particles and ozone. The strong irritant sulphur dioxide can, in combination with water droplets, form damaging acid. Medical examinations of children living in areas with high acid particle concentrations showed above-average numbers of bronchitis cases, and more children with restricted lung functions.
Bright sunlight converts nitrogen dioxide and volatile organic compounds to harmful ground-level ozone. Ozone attacks the mucus membranes of the airways, causing wheezing, coughing and infections. Exposure to high levels of ozone can lead to the development of asthma. Data from several studies also link ozone to an increased death rate amongst vulnerable persons.
People at risk
Heavily polluted air is a health risk for everyone. At particular risk are:
- People who exert themselves during episodes of high pollution levels. Outdoor workers, athletes and people participating in strenuous outdoor activities breathe fast and deep to supply the body with additional oxygen. Along with the oxygen, however, more pollutants reach the lungs. Because some pollutants, in particular ozone, can impair the lung function, the muscles don’t receive the required oxygen and so underperform.
- Infants and children are more likely to suffer from polluted air than healthy adults. Relative to their body size, children breathe a high volume of air, and breathe quickly. In addition, their underdeveloped respiratory system easily becomes irritated. The most recent studies also found a link between air pollution and an impaired immune system in children.
- People already suffering from existing respiratory disorders often have their symptoms of asthma, bronchitis, emphysema and other lung diseases intensified due to air pollutants.