Environmental Health: Radiation

It is sometimes difficult to appreciate just how many different types of electromagnetic radiation impinge on us and our environment. This is largely because, with the exceptions of light and heat, we can't see or feel them. The electromagnetic spectrum comprises a large range of radiation with very different wavelengths and properties, but many aspects of this radiation are little understood, and , still less, what effect they have on our general health and well-being.

This section looks at the most important types of radiation that are known to affect us in our homes, and in the renovation of our houses. First, ionizing radiation and its main source (radon) are looked at, as are the ways in which we can keep it from entering our homes. Secondly, non-ionizing radiation in all its various forms—ultraviolet and visible light, heat, microwaves, and radio waves—are analyzed in terms of their known effects on our health.

The Electromagnetic Spectrum:

The table above gives some idea of the different types of radiation within the electromagnetic spectrum. All electromagnetic radiation consists of energy waves travelling at the speed of light. It is very difficult for us to visualize these waves, as their properties are mostly outside our normal experience. Our best model of radiation is visible light, since we can follow its path this gives us a little insight into how these other kinds of energy waves behave. When this radiant energy strikes matter it can, if strong enough, permanently alter its state.

The most important distinction for health within the electromagnetic spectrum is that between ionizing and non-ionizing radiation. In the case of ionizing radiation, some of these waves—the alpha and beta waves—are in the form of charged particles that can collide with atoms and molecules, knock out electrons, and form ions. The other ionizing rays consist of gamma rays, x rays, and part of the ultraviolet spectrum.

Non-ionizing radiation also consists of energy waves that act on matter by transferring energy, usually in some form of vibrations or heat; but non- ionizing radiation does not have the ability to change the structure of atoms. Its wavelengths are longer than those of ionizing radiation and act on a supra- atomic scale. Mild non-ionizing radiation simply creates resonances, which can be subtle and unpredictable in their effects.

IONIZING RADIATION

Ionizing radiation is the most dangerous type of radiation for living organ isms, although, paradoxically, without its presence it is unlikely that life would have come into being and evolved in the first place. When cells are affected by ionizing radiation, various degrees of damage can be caused. With a strong dose, cells can die or fail to reproduce. Ionizing radiation is, after all, used medically to kill cancerous cells. With a weaker dose, genetic material in the cell can be altered or its biochemical mechanisms affected. In most cases a healthy body will identify sick or malfunctioning cells and destroy them, but sometimes damaged cells may survive and go on to repro duce abnormally. This can result in altered cell behavior, cancerous growth, or, even if the damage occurs in genes of the reproductive cells, genetic mutations.

There are many sources of ionizing radiation that we live with:

From within Our Bodies:

• Radioactive elements that have always occurred naturally in our bodies, such as radioactive potassium

• Radioactive elements in our bodies that are a result of the products of artificial nuclear fission, such as strontium 90

From Our Environment:

• Radiation from natural sources on the planet, such as uranium and radon, and from building materials containing such radioactive elements

• Radiation from the fallout from artificial nuclear explosions and power station accidents

• Radiation from artificial sources within our immediate environment, such as fluorescent dials, TVs, some smoke alarms, and x-rays (these can be categorized as personal, domestic, industrial, or medical sources)

From the Cosmos:

• Radiation from the cosmos: the sun and cosmic radiation. Most of this radiation is shielded from us by molecules in the atmosphere, such as ozone. Small amounts do penetrate, however, such as ionizing ultraviolet radiation.

In Our Homes Our Main Concerns Are:

• Radioactive elements in the ground and building materials (in particular the gases radon and thoron that are given off by these elements)

• Ionizing radiation from domestic appliances, including some smoke alarms and cathode-ray tubes (televisions and computers)

• Ionizing radiation from the sun (see ULTRAVIOLET)

RADON

Radon is a natural radioactive gas that is produced from the decay of uranium via radium. As there are traces of uranium and radium in all soils and rocks, radon is continually being emitted from the ground. It has a radioactive half-life of 3.8 days. When it is emitted into the open air it is rapidly diluted, but if it enters a basement or underfloor cavity, its concentration can build up if it is not vented away. People exposed to high radon concentrations for long periods of time have an increased risk of lung cancer. It has recently been discovered that the radon molecules themselves lodge in the lungs and cause the damage by emitting very short-range but deadly alpha rays. It has now been estimated that in Britain as many as 2,500 deaths from lung cancer a year are a direct result of radon exposure. Thoron is another radioactive gas to which people are exposed, but its half-life is only about one minute and so it does not diffuse far from its point of origin.

Radon from the Ground

There are four factors which affect the concentration and buildup of radon within a building:

• The concentration of radium in the ground. This varies enormously, from sedimentary rocks to ground containing uranium ore. The highest concentrations in the UK are found in south west England, where the source is granite.

• The permeability of the ground. Sand and gravel provide the most permeable conditions, whereas heavy clay and rock provide the opposite.

• Penetrability of the building. Cracks, construction joints, and gaps around service pipes all provide pathways for the gas.

• Reduced air pressure in buildings. The air in buildings is frequently at a slightly lower pressure than outside owing to the stack effect and extraction fans. This has the effect of drawing the gas into the building (see DRAFT-PROOFING and VENTILATING section).

Radon will only be a major cause for concern if you are living in a high- risk area (see the map of high-risk areas in North America). There are two tests currently available for detecting radon in the home. Charcoal- adsorption tests involve placing canisters of activated charcoal in various locations in the home. Within a few days, the charcoal granules will adsorb any radon gas that is present, and the test canisters are then sent to a lab for analysis. Charcoal-adsorption testing is useful for indicating whether or not your home may have a radon problem, but it does not work in humid locations like a bathroom or a damp basement.

Alpha-track tests, on the other hand, work effectively in humid locations and offer a more accurate, long-term sampling of radon in the home. Small strips of photographic paper inside canisters record the tracks of alpha particles given off by the radioactive decay of radon. These alpha-track canisters may be left in place for periods ranging from a month to a year. Like the char coal-adsorption test, the alpha-track canisters are then sent to a lab for testing and analysis. Best results are obtained by placing two or three canisters in three different locations in the home, including the basement if you have one.

To find an approved radon-testing company, contact your local government or regional office of the Environmental Protection Agency (EPA), or turn to the ORGANIZATIONS section in Part 5 of this guide.

Regions with potentially high radon activity. Dark shading indicates areas where soil or rocks may contain uranium and produce radon, though radon problems can also occur elsewhere. (Map is reproduced from Your Home, Your Health, and Well-Being, by Rousseau, et al; Hartley and Marks, 1989. Used by permission. Sources: U.S. Environmental Protection Agency and Energy, Mines and Resources Canada, 2003.)

What to Do If You Find You Have a Radon Buildup

Since radon gas is only likely to accumulate in unventilated basements and floor spaces that have a direct pathway to the ground, it is the ventilation and sealing of potential radon routes in these areas with which you should be concerned. In most houses with ventilated underfloor spaces, it is a relatively simple process to increase the ventilation to this space and seal the floor between. If you have a basement or cellar that you visit infrequently, you can treat this as though it were part of the ventilated space under the house: ensure it is well ventilated and that the door to the cellar or basement is properly draft- proofed. If, on the other hand, you have solid floors, or a basement that is used for sleeping or day- to day living, there is a probability of radon infiltration. There are three approaches to this problem:

Dealing with radon: Suspended floor; etc.

• Install a vapor-proof barrier in the floor and in any walls below ground level.

• Ensure adequate ventilation of the living areas.

• Reduce the pressure of the radon gas in the ground from where it emanates, immediately below the floor concerned. One way to accomplish this is by installing radon sumps. Air is sucked out of the sump by a fan, thus reducing the chance of radon being pressured through small cracks. The illustration above shows possible arrangements for doing this.

Radon from Building Materials

Virtually all building materials contain uranium and so emit minute amounts of radon. Building materials also emit gamma rays. In most cases the amounts are so small as to be negligible, but it has been found that certain building materials such as crushed granite bricks and blocks do emit significant amounts of radon. The same measures should be taken as with basement areas, that is, ensure a vapor-proof barrier on the inside of the walls that will contain the radioactivity. Certain paints can be used to provide this barrier.

Radioactivity from Household Appliances

Some smoke detectors have a radioactive source: however, danger only occurs from close exposure over long periods of time. By ensuring that smoke detectors are placed on ceilings well away from beds or sitting areas, this danger can be almost completely eliminated. With TVs and computer screens the ionizing radiation is very small, but it is advisable to limit prolonged and close exposure to this type of equipment.

NON-IONIZING RADIATION

Non-ionizing radiation includes part of the ultraviolet spectrum, visible light, infrared, microwaves, and radio waves. All these forms of radiation consist of energy waves which act on matter by transferring energy in the form of electromagnetic vibrations. Much of the natural non-ionizing radiation is essential for life: light and heat from the sun being the most obvious examples. Other forms, such as ultraviolet and the earth’s electromagnetic pulse, are also important to our health. All these forms of radiation are beneficial to us in the average doses that normally occur, but become harmful if their intensity increases beyond a certain point. Sources of non-ionizing radiation are:

• Our own bodies (mainly heat)

• Our homes: lighting, heating, microwave ovens, TVs, computers, and most forms of electrical equipment when in operation

• Natural external sources: the sun, the cosmos, the earth’s magnetic field, and the earth’s electromagnetic pulse

• Synthetic external sources: radio and TV broadcasting, microwave transmissions, electricity generation and distribution systems, and radar

Many of the forms listed above are radio waves, and there is no doubt that, given a high enough intensity, even these wavelengths can be harmful to human health; however, in most cases the level we receive is extremely low. It is difficult for us to predict, given our present knowledge, that a particular radiation field will produce any particular effect on our bodies. However, since so many of the processes within our bodies are dependent upon electromagnetic interactions between molecules, it would indeed be surprising if these fields did not have some effect on our central nervous system. Research in this area is developing quickly, and more precise information should be available in the near future.

Ultraviolet (UV) Radiation

Ultraviolet covers a large range of wavelengths—ten times that of the range of visible light. Just as visible light has different properties for different wave lengths, so does ultraviolet, with the shorter wavelengths being more destructive and having ionizing properties. At present we seem to be much more concerned with the ultraviolet component of sunlight that causes skin cancer than with the longer wavelengths that are actually beneficial to our health. Contrary to what we may think, regular doses of sunlight generally appear to help prevent cancer. ‘What is it then that causes skin cancer? It is simply sunburn, which is an overdose of solar radiation containing destructive ionizing UV radiation. This overexposure to ultraviolet light is the same as with many wave energies: a mild dose is positive, a medium one is stimulating, and a strong one is harmful. Before World War II it was generally accepted that being out in the sun was healthy; hospitals had verandas and balconies on which patients could take in the sun’s health-giving rays. Besides producing vitamin D, ultraviolet light also cleanses the blood by killing bacteria in it as it passes through our surface blood vessels. It also reduces the risk of heart disease and some cancers.

The Depletion of the Ozone Layer

The depletion of the protective layer of ozone (03) molecules in the upper atmosphere, primarily as a result of the release of chlorofluorocarbons (CFCs), means that fewer and fewer of the damaging ultraviolet rays are filtered out before they reach the earth’s surface. There is uncertainty about quite how this will effect the biosphere as a whole, or human beings in particular. However, we in the northern latitudes, hidden away inside our homes for much of the time, on average need to increase our overall expo sure to UV radiation. Our problem is that we tend to go for a whole year’s supply on one sunny Memorial Day weekend or during a week’s vacation in the Caribbean. This leads to very intense exposure for vulnerable skin, the cells of which can be seriously damaged.

The Filtering Effect of Glass

Glass filters out UV light, which is useful in that it prevents the degradation of materials inside the home, but it is not so useful for our health. If we could build sunrooms that were transparent to the healthy wavelengths of ultraviolet, we could sit in the sun even on cold days and soak up our weekly dose of ultraviolet light. Such glass used to be available before World War II, but is no longer obtainable. However, most plastics do allow ultra violet to pass through, so an alternative might be to glaze over part of our sunspace or even a balcony with a suitable type of plastic pane. Certain plastics are being increasingly used for glazing.

Full-Spectrum Lighting

Another way of exposing ourselves to ultraviolet light while indoors is through the use of full-spectrum lighting. This lighting produces a mix of wavelengths similar to that of the sun, including ultraviolet radiation. If we were to include this type of lighting in rooms such as bathrooms or bedrooms, where we remove our clothes, we could increase our dose of ultraviolet light, particularly in the winter when we most need it. At present, full-spectrum fittings are available in tubes and housings similar to the old- style fluorescent light units. Since all fluorescent lighting is based initially on the production of ultraviolet, it should soon be possible for manufacturers to produce fittings in any of the compact versions now available (see LIGHTING).

Visible Light

Most energy from the sun is radiated in the form of light. Plants developed photosynthesis in order for them to make use of this most abundant source of energy, and our eyes developed sensitivity to it for the same reason. Sunlight thus plays a very important part in our overall well-being.

Seasonal Affective Disorder (SAD)

Sleepiness is partly caused by the hormone melatonin, which is secreted by the pineal gland in the brain during darkness or dim light. However, if we are in the dark or in dimly lit interiors for long periods of time, melatonin is overproduced and can cause a depression known as seasonal affective disorder (SAD). If someone is suffering from this syndrome (and it may be something we all suffer from to a greater or lesser extent in winter), the usual therapy prescribed for this condition is exposure to bright, full-spectrum light. Bright light in general has the effect of making us feel more positive and awake, and for this reason we need to ensure there is plenty of natural light in our home (see LIGHTING section). This provides yet another reason for having a conservatory or sunroom that we can use when we feel the need.

Glare

There are various forms of poor lighting that cause problems for the eyes and that can, in turn, result in increased stress, headaches, and eyestrain. The most common problem is that of glare. The eye adapts to the average light intensity of what it is looking at, but if there is a very bright area in the field of vision then discomfort is experienced. There are three types of glare that are commonly identified:

• Disability glare is caused by direct, intense light affecting the ability of the eye(s) to view an object.

• Discomfort glare arises from long-term glare from windows and light fittings that are in the field of view.

• Reflected glare is common where the object is shiny and either a window or a light is reflected from its surface.

Glare can usually be avoided by lighting the task more brightly (two or three times) than the immediate surroundings, with the further background even less bright. Extremes of brightness should be avoided.

Color

The effects of different colors on us in terms of health are not yet fully under stood. However, since color is such an important part of light, it is worth looking at some of the effects that have been observed. Certain themes run throughout and are common to many studies.

Effects of Different Colors

Some of the results of research suggest that colors work on our subconscious mind. However, colors also correspond to different bands of wave length within the light spectrum and to different neural stimuli within the eye. There is some evidence to suggest that different parts of the brain are stimulated by the different wavelengths of different colors. As with so much medical research, separating the physiological from the physical is difficult. At present the main findings remain empirical and , as might be expected, there are large cultural and personal variations. For some people color is very important and has a clear influence on their state of mind. If you are one of these people, use the colors in your home that feel right for you.

Infrared

Infrared radiation is emitted by every single object in proportion to its temperature. Heat is essential to life, and radiated heat is one of the major factors that makes us feel warm or cold; this subject is further dealt with in SPACE HEATING. We are well protected by our senses when it comes to heat, since our skin is very sensitive to temperature.

Infrared wavelength controls are increasingly being used in domestic environments to turn lights on and off and provide security systems. Like visible light, infrared is an essential and integral part of our environment. At low intensities it is completely benign.

Microwaves

Our potential exposure to microwaves is mostly through microwave cooking. If you own a microwave oven, it is important to understand the effects of microwave radiation if it “leaks” out of the appliance. There are two ways in which microwaves can affect the body:

• By direct heating of the body
• By non-thermal effects

The first is straightforward. Direct heating takes place, and if too intense will overheat or burn the exposed parts of the body. The eyes are particularly vulnerable. The non-thermal effects of microwaves are less clear, but there seems to be strong evidence that they can be harmful; we should guard ourselves against unnecessary exposure by keeping door seals to microwave ovens in good condition.

Radio Waves

Besides those produced by radio transmitters, radio waves of different types are produced by most electrical installations. In fact all electric current flowing through cables or wires creates radiation: the larger the current, the stronger the radiation. Power transmission lines carry very large voltages and emit correspondingly high amounts of radiation. There is now some evidence that there may be a link between proximity to these power lines and the incidence of leukemia and cancer. Children are most affected, and the danger seems to be at its greatest when people sleep close to these cables. How much we are affected by the electric cables in our homes is more difficult to determine; however, some scientists advise reducing or eliminating electrical equipment near your bed, or shielding electric circuits. One reason that radiation from electronic equipment and circuits can present a health risk is that much of it is in the form of alternating current.

Alternating and Direct Current

All domestic supplies that come from central grids are alternating current (AC). Unlike direct current (DC), where the current is continuous in one direction, AC reverses its flow continually in an alternating cycle. This frequency is 50 cycles per second (50 hertz) in the UK (60 hertz in the US). Alternating current is the preferred form of electricity supply for numerous reasons: it can be transmitted over long distances at high voltages with little loss of power; it can be also converted easily from one voltage to another, or to DC, as required by the end user. However, this alternating frequency gives rise to radiation that coincides with frequencies used by the brain. It is still not understood what effect this has, but there is evidence to suggest that some people’s mental abilities are impaired. This is a rapidly growing field of research and may prove another reason for reducing our excessive dependence on high-voltage electrical power.

Schumann Waves

Schumann waves are a natural form of radiation emanating from the earth’s electromagnetic field, which pulses at the rate of 7.83 beats a second. These waves are thought to be essential to our well-being, partly because the human body’s bioelectrical system also pulses at about the same rate, and because, when astronauts become separated from this pulse, they experience a loss of orientation. This pulse is now provided synthetically on all spacecraft to ensure the health of the crews. What is not so clear is how the earth’s pulse may be masked or deflected by buildings and metal components in buildings. It is clear that some people find they can't sleep well in particular locations and orientations, although this may be for reasons other than a lack of Schumann waves.

PRIORITIES FOR ACTION

+ If you live in a high-risk radon area and have not yet taken precautions, contact an EPA-approved radon test supplier (see the Organizations section in Part Five) and conduct a radon test for your home. Undertake the measures outlined above if necessary.

+ Consider building a sunspace or covered balcony with glass or plastic that allows ultraviolet through to provide a healthier environment for you and your plants.

+ Consider installing full-spectrum lighting in your bath room or bedroom.

+ If you have a choice, arrange your rooms to follow the sun to make the best use of bright sunlight, especially in winter to reduce seasonal affective disorder (SAD).

+ If you have an old microwave oven, check to see that its door is sealed properly. A damp cloth held in front of the appliance will warm up where leakage is occurring.

+ If you have high-voltage cables or transformer stations nearby, you can use a portable radio to “listen” to the interference produced. If you can pickup any of this interference in your home, sleep in one of the rooms that are least affected.

Next: Sound

Prev: Water

Top of page  All Related Articles    Home