Saturday, April 5, 2008

War Against Noise II


2. NOISE AND DISEASES

Picking off from where we stopped, another hazard noise portends is advent of overt diseases!

For the most part, human beings are rather predictable. We tend to respond to respond to issues and situations in predictable ways. The predictability also affects our response to noise. We are wired to see sudden and loud sounds as a call for action. In readiness for dangerous and harmful situations, our bodies make automatic and unconscious responses to sudden or loud sounds. Of course, most noise in our modern society does not signify such danger. However, our bodies still react as if these sounds were always a threat or warning.

In effect, the body shifts gears. Blood pressure rises, heart rate and breathing speed up, muscles tense, hormones are released into the bloodstream, and perspiration appears. These changes are observed to occur even during sleep lending credence to the predictability of this response.

The idea that people get used to noise is a myth. A potentially dangerous myth. Even when we think we have become accustomed to noise, biological changes still take place inside us, preparing us for physical activity if necessary.

Noise does not have to be loud to bring on these responses. Noise below the levels usually associated with hearing damage can cause regular and predictable changes in the body.

What happens to the human body when confronted with ever-present noise? In a world where steady bombardment of noise is the rule rather than the exception, the cumulative effects of noise on our bodies may be quite extensive. It may be that our bodies are kept in a near-constant condition of agitation. Researchers debate whether the body's automatic responses build on each other, leading to what are called the "diseases of adaptation." These diseases of stress include ulcers, asthma, high blood pressure, headaches, and colitis.

In studies dating back to the 1930s, researchers noted that noise developed marked digestive changes which were thought to lead to ulcers. Cases of ulcers in certain noisy industries have been found to be up to five times as numerous as what normally would be expected.

Similar research has identified more clearly the contribution of noise to other physical disorders. A five-year study of two manufacturing firms in the United States found that workers in noisy plant areas showed greater numbers of diagnosed medical problems, including respiratory ailments, than did workers in quieter areas of the plants.

From a study done with animals, researchers concluded that noise may be a risk factor in lowering people's resistance to disease and infection.

To prevent aggravation of existing disease, doctors and health researchers agree that there is an absolute requirement for rest and relaxation at regular intervals to maintain adequate mental and physical health. Constant exposure to stress from noise frustrates this requirement. In doing so, it has a potentially harmful effect on our health and well-being.

Noise may just be killing you! Stop Noise!!!

...to be continued.

War Against Noise

Our capacity to perceive and distinguish sounds is one of the abilities our ears confer upon us. Sounds are one of the things that add colour and beauty to life. But unfortunately many people today are laying a foundation for an old age of deafness. Many people are ignorantly destroying their capacity to enjoy the beauty of sounds. Consider the following facts about deafness and hardness of hearing:

• 278 million people worldwide have moderate to profound hearing loss in both ears.
• 80% of deaf and hearing-impaired people live in low- and middle-income countries (e.g. Nigeria).
• In developing countries, fewer than 1 in 40 people who would benefit from a hearing aid have one.
• 50% of deafness and hearing impairment is avoidable through prevention, early diagnosis, and management.
Imagine that! For a whooping 139,000,000 people, deafness/hard of hearing was a totally preventable affair. My focus today is to lend a hand to prevention of deafness.

The Enemy Called NOISE

Noise is each unwanted sound which has a disturbing irritating character, or has harmful effects, irrespective of its intensity, which in many cases is not of major importance.

Sounds are simply vibrations of particles picked by intricate mechanisms in our ears and brains. The unit of measurement for the number oscillations per second of the media these vibrations are traveling through is called Hertz (after the renowned 19th century German physicist Heinrich Hertz), while the intensity (loudness) of these vibrations is referred to as decibel (dB). The full, audible frequency range for young, healthy ears extends from about 20 Hz (cycles per second) to about 20,000 Hz. However, the human hearing mechanism is most sensitive to sounds in the 500- to 8,000-Hz range. Above and below this range, the ear is inherently less sensitive.

With increasing age, the ear becomes progressively less sensitive to sound over the entire frequency range (i.e. a condition known as presbycusis). Persons who are exposed to loud noise over a long period of time can also incur a hearing loss that usually most significantly affects hearing acuity in the mid- and high-frequency ranges. To account for the varying sensitivity of the normal human ear to sound over the audible frequency range, sound level meters incorporate an electronic filter (or weighting network) that approximates the way the human ear perceives sound over the audible frequency range. Sound level values obtained using this weighting network are referred to as "A-weighted" sound levels and are signified by the identifying unit, dBA.

To give some perspective to this simple sound level descriptor, the figure to the left shows A-weighted levels over the full dynamic range of human hearing, from very quiet concert halls and recording studios at about 20 dBA, up to levels of 130 dBA that would cause pain and potential hearing damage, even for short time exposures.

I can almost bet that for the majority of people reading this that it is the first time you will be coming across this measurements and values and may in fact be wondering what they have to do with you. Well, they have a lot to do with you.






Let’s look at the health hazards noise portends:

1. HEARING LOSS


Children exposed to sounds over 120 decibels risk permanent deafness.

This is known as Noise Induced Hearing Loss (NIHL). According to the WHO, NIHL is the most common irreversible occupational hazard in the world. NIHL is irreversible but totally preventable. NIHL can be caused by a one-time exposure to loud sound, as well as by repeated exposure to sounds at various loudness levels over an extended period of time. Regular exposure of more than 1minute to sound of 110 decibels risks permanent hearing loss while prolonged exposure to any noise above 90 decibels can cause gradual hearing loss. Children exposed to sounds over 120 decibels risk permanent deafness.

To illustrate this progressive deafness, let me share with you an experience I had a while back. I once had the misfortune of boarding an 18-seater bus from Ife to Lagos with 16 market women. It was 3 hours of pure agony. Can you imagine 16 women all screaming at the top of their voices to carry out conversation with one another. They didn’t sleep nor pause to buy anything on they road. It was a horrible cacophony of voices. I got down from the bus with a blistering headache and a vow never to enter a vehicle with more than 2 market women! Obviously these women were becoming progressively deaf. Their market must be a very noisy place indeed.

One of the first signs of hearing loss is difficulty hearing high frequency sounds in speech, music or nature. "Ringing" in the ears at the end of the workday or "better" hearing in the morning than after work often indicates hearing loss may be developing. Once the amount of hearing loss becomes substantial difficulties are encountered in hearing conversation in social gatherings and at home. This can lead to feelings of isolation, loneliness and frustration. Noise induced hearing loss most often does not cause pain or discomfort and often goes unnoticed until a substantial amount of loss has already occurred. People often think they are getting used to loud noise when in reality they are slowly losing their hearing and once lost, hearing cannot be repaired by the body or through medical intervention. Hearing aids only provide limited relief and are expensive.

Overexposure to loud noise can also lead to "tinnitus", an extremely irritating "ringing" in the ears or head. This can persist for a lifetime, disturbing sleep and life in general.
A study was conducted on the primitive Mabaans of the African Sudan. Their environment was almost free of noise with a typical background level of 40 dBA. Among the Mabaans, the hearing abilities of men in their seventies and eighties is equal to that of healthy children at age ten

Noise can cause permanent deafness.

...to be continued

Saturday, March 8, 2008

THE TELECOMS INDUSTRY AND YOUR HEALTH



In recent times Nigeria has been undergoing a communications revolution. We have gone from the dark days of queuing up for hours just to make a single phone call with the overwhelming majority of Nigerians having no visible hope of ever owning a telephone line, to a season of phone lines costing virtually nothing. All this have happened within a relatively short period of time.

This revolution has however thrown up some dust with the quality of service currently being on the front burners. The ongoing Senate’s Public inquiry on dropped calls holds the promise of an improvement in the quality of service being provided by the service providers. Everyone is waiting for the outcome of the inquiry

In many circles, worries and concerns are being expressed on the health consequences of this revolution.

Base stations and wireless technologies
Mobile telephony is now commonplace around the world. There are estimated to over 2 billion mobile phone users worldwide. This about 1/3rd of the world’s population. This figure is rapidly increasing. This wireless technology relies upon an extensive network of fixed antennas, or base stations, relaying information with radiofrequency (RF) signals. Over 1.4 million base stations exist worldwide and the number is increasing significantly with the introduction of third generation technology.
Other wireless networks that allow high-speed internet access and services, such as wireless local area networks (WLANs), are also increasingly common in homes, offices, and many public areas (airports, schools, residential and urban areas). As the number of base stations and local wireless networks increases, so does the RF exposure of the population.

Let’s look at the various health concerns that have been expressed.

HEALTH CONCERNS
A common concern about base station and local wireless network antennas relates to the possible long-term health effects that whole-body exposure to the RF signals may have. According to the World Health Organization (WHO) to date, the only health effect from RF fields identified in scientific reviews has been related to an increase in body temperature (> 1 °C) from exposure at very high field intensity found only in certain industrial facilities, such as RF heaters. The levels of RF exposure from base stations and wireless networks are so low that the temperature increases are insignificant and do not affect human health.

The strength of RF fields is greatest at its source, and diminishes quickly with distance. Access near base station antennas is restricted where RF signals may exceed international exposure limits. Recent surveys have indicated that RF exposures from base stations and wireless technologies in publicly accessible areas (including schools and hospitals) are normally thousands of times below international standards.

In fact, due to their lower frequency, at similar RF exposure levels, the body absorbs up to five times more of the signal from FM radio and television than from base stations. This is because the frequencies used in FM radio (around 100 MHz) and in TV broadcasting (around 300 to 400 MHz) are lower than those employed in mobile telephony (900 MHz and 1800 MHz) and because a person's height makes the body an efficient receiving antenna (So you now know why sometimes your television shows better when you are holding the antenna i.e. feje run :). Furthermore, radio and television broadcast stations have been in operation for the past 50 or more years without any adverse health consequence being established.

While most radio technologies have used analog signals, modern wireless telecommunications are using digital transmissions. Detailed reviews conducted so far have not revealed any hazard specific to different RF modulations.

Cancer: Media or anecdotal reports of cancer clusters around mobile phone base stations have heightened public concern. It should be noted that geographically, cancers are unevenly distributed among any population. Given the widespread presence of base stations in the environment, it is expected that possible cancer clusters will occur near base stations merely by chance. Moreover, the reported cancers in these clusters are often a collection of different types of cancer with no common characteristics and hence unlikely to have a common cause.

Scientific evidence on the distribution of cancer in the population can be obtained through carefully planned and executed epidemiological studies. Over the past 15 years, studies examining a potential relationship between RF transmitters and cancer have been published. These studies have not provided evidence that RF exposure from the transmitters increases the risk of cancer. Likewise, long-term animal studies have not established an increased risk of cancer from exposure to RF fields, even at levels that are much higher than produced by base stations and wireless networks.

Other effects: Few studies have investigated general health effects in individuals exposed to RF fields from base stations. This is because of the difficulty in distinguishing possible health effects from the very low signals emitted by base stations from other higher strength RF signals in the environment. Most studies have focused on the RF exposures of mobile phone users. Human and animal studies examining brain wave patterns, cognition and behaviour after exposure to RF fields, such as those generated by mobile phones, have not identified adverse effects. RF exposures used in these studies were about 1000 times higher than those associated with general public exposure from base stations or wireless networks. No consistent evidence of altered sleep or cardiovascular function has been reported.

Some individuals have reported that they experience non-specific symptoms upon exposure to RF fields emitted from base stations and other EMF devices. As recognized in a recent WHO report "Electromagnetic Hypersensitivity", EMF has not been shown to cause such symptoms. Nonetheless, it is important to recognize the plight of people suffering from these symptoms.

From all evidence accumulated so far, no adverse short- or long-term health effects have been shown to occur from the RF signals produced by base stations. Since wireless networks produce generally lower RF signals than base stations, no adverse health effects are expected from exposure to them.

PROTECTION STANDARDS
International exposure guidelines have been developed to provide protection against established effects from RF fields by the International Commission on Non-Ionizing Radiation Protection (ICNIRP, 1998) and the Institute of Electrical and Electronic Engineers (IEEE, 2005).

National authorities should adopt international standards to protect their citizens against adverse levels of RF fields. They should restrict access to areas where exposure limits may be exceeded.

PUBLIC PERCEPTION OF RISK

Some people perceive risks from RF exposure as likely and even possibly severe. Several reasons for public fear include media announcements of new and unconfirmed scientific studies, leading to a feeling of uncertainty and a perception that there may be unknown or undiscovered hazards. Other factors are aesthetic concerns and a feeling of a lack of control or input to the process of determining the location of new base stations. Experience shows that education programmes as well as effective communications and involvement of the public and other stakeholders at appropriate stages of the decision process before installing RF sources can enhance public confidence and acceptability.

CONCLUSIONS
Considering the very low exposure levels and research results collected to date, there is no convincing scientific evidence that the weak RF signals from base stations and wireless networks cause adverse health effects.

This is not to say however that the debate on the possible health consequences of base stations and RF is over.

Add your voice to the debate. Do you think RF pose a health hazard?

Ciao