Definition of the exposure indicator
The most appropiate exposure measurement for occupational noise is the A-weighted
to damage human hearing. most commonly used epidemiological measurement of exposure. Exposure is initially
asessing the burden of disease. exposure above and below cut-off values, rather than as a distribution. limits in developed (usually 85 dB(A)) and many developing (usually 90 dB(A))
countries for an 8-hour day (Hessel & Sluis-Cremer, 1987; Alidrisi et al., 1990;
Shaikh, 1996; Hernandez-Gaytan et al., 2000; Osibogun, Igweze & Adeniran, 2000;
Sriwattanatamma & Breysse, 2000; Ahmed et al., 2001):
− minimum noise exposure: <85 dB(A)
− moderately high noise exposure: 85−90 dB(A)
− high noise exposure: >90 dB(A).
4.2 Determining the distribution of exposure in the population
The most accurate assessments of health impacts at the national level are obtained
from local exposure data, since population exposure distributions can vary between
countries. The most commonly used methods to assess health impacts are:
− area surveys: noise levels are measured at different sites across an area, such as
− dosimetry: a person’s cumulative exposure to noise over a period of time is
measured with a dosimeter;
− engineering surveys: noise is measured using a range of instruments.
Ideally, representative data will be available on the average levels of occupational
noise for all major occupations within the country, either from the published scientific
literature or from other sources of data. If such data are not available,
epidemiological surveys can be carried out to determine the distribution of noise
exposure by occupation. distribution will have to be estimated from existing sources of information. A reasonable estimate of the exposure distribution can be obtained by extrapolating
from existing data for studies undertaken elsewhere, provided that the data are from
similar occupational environments. determinant of exposure level is worker occupation. Industry-specific studies in the
perceived hearing loss, and 90% of coal miners have hearing impairment by age 52
Also, it is estimated that 70% of male metal/nonmetal miners will have hearing
impairment by age 60 years (NIOSH, 1991). workplace-specific factors will also influence the level of exposure. These factors
whether there are engineering and work practice controls; and whether personal
protective devices are used and properly maintained. developed countries than in developing countries). extrapolations should be made from data for comparable occupations in comparable
countries.
The Global Burden of Disease study estimated exposure distributions using an
occupational category approach, modified to reflect the different noise exposures for
occupations in different economic subsectors. national level, using country data where available, or by extrapolating from data for
other studies if local data are not available.
The first step is to assess the proportion of workers in each occupational category that
is exposed to at least moderately high occupational noise levels (>85 dB(A)); see
Table 4). If these data are not available from national surveys, the distribution can be
based on the results of a large survey in the USA (DHHS, 1986; NIOSH, 1998). For each occupational category, the proportion of production workers exposed to high
noise levels (i.e. >90 dB(A)) is estimated from a survey of over 9 million production
workers in the USA carried out by the USA Occupational Safety and Health
Administration in 1981 (cited in NIOSH 1991; DHHS, 1986). shown in bold font in Table 4. Of the 6 063 000 production workers with exposures
at or above 85 dB(A), 3 407 000 (or 56%) were exposed to noise levels above 90
dB(A). We therefore estimate that among production workers exposed at or above 85
dB(A), half were exposed at 85–90 dB(A), and half were exposed at >90 dB(A).
Exposures in the remaining occupational categories and economic subsectors are
estimated either by extrapolation from the most relevant subsector of the survey of
production workers (figures shown in italics in Table 4), or by expert judgement
the agricultural workers and sales and service workers exposed at or above 85 dB(A),
approximately 70% are exposed at 85–90 dB(A), and 30% at >90 dB(A). All
professional, administrative, and clerical workers with noise exposure at or above 85
dB(A) are assumed to be in the 85–90 dB(A) exposure level.
the country in which the assessment is undertaken. In developing countries, because
hearing conservation programmes are rare, the global assessment assumed that only
5% of the production workers would be exposed at the 85–90 dB(A) level, and 95%
would be exposed at the >90 dB(A) level. exposed at or above 85 dB(A) are assigned to the 85–90 dB(A) level, because
mechanization is not widespread in countries in WHO developing subregions (e.g.
The second step consists of defining the proportions of workers in each economic
subsector, by occupational category. These data may be available from national
proportion of workers in each occupation is multiplied by the proportion of workers in
the occupation exposed to moderately high, or high, noise levels). proportion of the working population in each economic subsector is determined by
gender. In the fifth step, these values are multiplied by the proportion of workers in
the occupational category exposed to the specific noise level. calculations is performed for all economic subsectors, and the results summed to give
the proportion of the total working population that is exposed at each noise level.
work, by defining the proportion of the working-age population that is currently
employed. the working-age population. Finally, the overall population exposure is given by
multiplying the proportion of the working population exposed at each exposure level,
by the proportion of the total population in work.
Table 5 summarizes these steps and the sources of data necessary to complete them,
and gives example calculations for the proportion of the male working-age population
in the USA that is exposed to moderately high noise levels. assessment of the exposure distribution, the calculations would be repeated for
exposure to high noise levels, and for females as well as males. Estimates for the prevalence of noise exposure, determined using the described
The figures assume there are equal employment rates
in all age groups of the working-age population.
readmore»
Showing posts with label pollution. Show all posts
Showing posts with label pollution. Show all posts
Saturday, April 24, 2010
Occupational noise
1. Introduction
Physically, there is no difference between sound and noise. Sound is a sensory
perception and noise corresponds to undesired sound. By extension, noise is any
unwarranted disturbance within a useful frequency band (NIOSH, 1991). Noise is
present in every human activity, and when assessing its impact on human well-being
it is usually classified either as occupational noise (i.e. noise in the workplace), or as
environmental noise, which includes noise in all other settings, whether at the
community, residential, or domestic level (e.g. traffic, playgrounds, sports, music).
This guide concerns only occupational noise; the health effects of environmental noise
are covered in a separate publication (de Hollander et al., 2004).
High levels of occupational noise remain a problem in all regions of the world. exposed to hazardous noise (NIOSH, 1998). (12−15% of the workforce) are exposed to noise levels defined as hazardous by WHO
Although noise is associated with almost every work activity, some
activities are associated with particularly high levels of noise, the most important of
flying commercial jets. Occupations at highest risk for NIHL include those in
manufacturing, transportation, mining, construction, agriculture and the military.
The situation is improving in developed countries, as more widespread appreciation of
Data for developing
countries are scarce, but available evidence suggests that average noise levels are well
above the occupational level recommended in many developed nations (Suter, 2000;
The average noise levels in developing countries may be
There are therefore several reasons to assess the burden of disease from occupational
noise at country or subnational levels. Occupational noise is a widespread risk factor,
with a strong evidence base linking it to an important health outcome (hearing loss).
It is also distinct from environmental noise, in that it is by definition associated with
An assessment of the burden of disease associated with occupational noise can help
guide policy and focus research on this problem. occupational noise (WHO/FIOH, 2001).
2. The risk factor and its health outcomes
2.1 Measuring noise levels
There are a variety of metrics for quantifying noise levels, the most useful of which
for measuring sound as a health hazard is described in de Hollander et al. (2004). In
account for the sensitivity of people to noise. These corrections depend on the noise
frequency and characteristics (impulse, intermittent or continuous noise levels), and
the source of noise. The following measures are most relevant for assessing
occupational noise levels.
Sound pressure level. The sound pressure level (L) is a measure of the air vibrations
that make up sound. Because the human ear can detect a wide range of sound
pressure levels (from 20 μPa to 200 Pa), they are measured on a logarithmic scale
with units of decibels (dB) to indicate the loudness of a sound.
Sound level. frequencies. To account for the perceived loudness of a sound, a spectral sensitivity
factor is used to weight the sound pressure level at different frequencies (A-filter).
These A-weighted sound pressure levels are expressed in units of dB(A).
Equivalent sound levels. When sound levels fluctuate in time, which is often the case
for occupational noise, the equivalent sound level is determined over a specific time
period. In this guide, the A-weighted sound level is averaged over a period of time
A common exposure period, T, in occupational
studies and regulations is 8 h, and the parameter is designated by the symbol, LAeq,8h.
2.2 Disease outcomes related to the risk factor
In general, the health consequences of a given level of occupational noise are likely to
review has therefore been carried out of all well-designed epidemiological studies that
link occupational noise exposure to health outcomes, regardless of where the study
The review of the literature indicates that noise has a series of health effects, in
addition to hearing impairment (Table 1). with noise in the workplace. Other consequences of workplace noise, such as
annoyance, hypertension, disturbance of psychosocial well-being, and psychiatric
disorders have also been described (de Hollander et al., 2004).
For occupational noise, the best characterized health outcome is hearing impairment.
The first effects of exposure to excess noise are typically an increase in the threshold
of hearing (threshold shift), as assessed by audiometry. hearing thresholds of an average 10 dB or more at 2000, 3000 and 4000 Hz in either
ear (poorer hearing) (NIOSH, 1998). NIHL is measured by comparing the threshold
of hearing at a specified frequency with a specified standard of normal hearing, and is
reported in units of decibel hearing loss (dBHL).
Threshold shift is the precursor of NIHL, the main outcome of occupational noise. It
accompanied by tinnitus. Because hearing impairment is usually gradual, the affected
worker will not notice changes in hearing ability until a large threshold shift has
occurred. Noise-induced hearing impairment occurs predominantly at higher
frequencies (3000−6000 Hz), with the largest effect at 4000 Hz. increases in severity with continued exposure.
− social isolation;
− impaired communication with coworkers and family;
− decreased ability to monitor the work environment (warning signals, equipment
sounds);
− increased injuries from impaired communication and isolation;
− anxiety, irritability, decreased self-esteem;
− lost productivity;
− expenses for workers’ compensation and hearing aids.
2.3 The strength of the evidence for disease outcomes
The mechanisms linking occupational noise to the health outcomes described in the
countries or regions. strength of relationships, other studies are usually relevant for assessing the strength
of evidence for causality.
Evidence is usually assessed on the grounds of biological plausibility, strength and
consistency of association, independence of confounding variables and reversibility
(Hill, 1965). psychosocial well-being, psychiatric disorders, and effects on performance are
plausible outcomes, but are only weakly supported by epidemiological evidence.
Other plausible outcomes include biochemical effects, immune system effects, and
birth-weight effects, but again there is limited evidence to support these outcomes.
There is stronger evidence of noise-based annoyance, defined as “a feeling of
resentment, displeasure, discomfort, dissatisfaction or offence which occurs when
noise interferes with someone’s thoughts, feelings or daily activities” (Passchier-
Vermeer, 1993). Noise annoyance is always assessed at the level of populations,
There is consistent evidence for annoyance in populations
about 42 dB(A). doubt that annoyance from noise adversely affects human well-being.
A recent meta-analysis reviewed the effects of occupational and environmental noise
on a variety of cardiovascular risks, including hypertension, use of anti-hypertension
drugs, consultation with a general practitioner or specialist, use of cardiovascular
medicines, angina pectoris, myocardial infarction and prevalence of ischaemic heart
disease (van Kempen et al., 2002). The analysis showed an association with
hypertension, but only limited evidence for an association with the other health
outcomes. Reasons for the limited evidence included methodological weaknesses,
such as poor (retrospective) exposure assessment, poorly controlled confounding
variables, and selection bias (such as the “healthy worker” effect, where the studied
work through disability). individual studies, and summary relative risks were statistically significant in only a
limited number of cases. Overall, the causal link is plausible, and the meta-analysis
provides support for further investigation of cardiovascular effects in the future.
the meta-analysis. Global Burden of Disease study, and methods for estimating the cardiovascular
effects of noise were not defined (Concha-Barrientos et al., 2004). This guide does
not therefore provide information for assessing the cardiovascular effects of noise at
national or local levels. the physical properties of noise and damage to the hearing system). supported by epidemiological studies that compared the prevalence of hearing loss in
different categories of occupations, or in particularly noisy occupations (e.g. Arndt et
al., 1996; Waitzman & Smith, 1998; Hessel, 2000; Palmer, Pannett & Griffin, 2001).
The studies showed a strong association between occupational noise and NIHL, an
effect that increased with the duration and magnitude of the noise exposure. For
example, the risk for “blue-collar” construction workers was 2 to >3.5-fold greater
(Table 2). exposure to vibrations, ototoxic drugs and some chemicals, the association with
occupational noise remains robust after accounting for these influences. epidemiological evidence for an effect of high levels of occupational exposure on
hearing loss in unborn children (e.g. Lalande, Hetu & Lambert, 1986), but there was
Global Burden of Disease study, and it is not covered further in this guide.
3.4 Health outcomes to include in the burden of disease assessment
The selection of a health outcome should be made principally on the strength of the
evidence of causality and on the availability of information for quantifying health
impacts. It is also important that the health outcome has been assessed within the
study population, or can reasonably be extrapolated from other populations. several possible sources for health statistics, including national health statistics, a
national burden of disease study, or “prior estimates” provided by WHO. More
(Prüss-Üstün et al., 2003).
Depending on the aim of the study, it may be preferable to assess disease burden in
terms of attributable disease incidence, or overall disease burden, using summary
measures of population health such as DALYs (Murray, Salomon & Mathers, 2000).
with the health burden from other risk factors. A goal of burden of disease
assessments is to maximize the compatibility of frameworks for assessing the burden
of disease for risk factors. associated with each disease.
health outcomes often assessed in national health statistics and as part of WHO
burden of disease assessments. se. Should annoyance cause other health outcomes, such as hypertension and
associated cardiovascular disease, then other outcomes could be considered. comparative disability weights independently, to take them from other studies (e.g. de
Hollander et al., 2004), or to extrapolate them from similar health outcomes. You
should be aware that an independent assessment of the severity of such outcomes
introduces additional uncertainty when the results are compared with other risk factors
This guide follows the previous global assessment of occupational noise, in that only
the effects of occupational noise on NIHL are assessed. Several definitions of hearing
impairment are available in the literature. In the occupational setting, hearing
impairment is generally defined as “ a binaural pure-tone average for the frequencies
Sriwattanatamma & Breysse, 2000). correspond to the WHO definition of disabling hearing loss (i.e. with an associated
disability weight, and corresponding to a quantifiable burden of disease). This level
of hearing impairment is defined as “permanent unaided hearing threshold level for
4000 kHz” (Table 3). prevalence of hearing loss that corresponds to the WHO definition, as it is preferable
for burden of disease assessments. procedure is supported by large epidemiological studies, and should therefore
readmore»
Physically, there is no difference between sound and noise. Sound is a sensory
perception and noise corresponds to undesired sound. By extension, noise is any
unwarranted disturbance within a useful frequency band (NIOSH, 1991). Noise is
present in every human activity, and when assessing its impact on human well-being
it is usually classified either as occupational noise (i.e. noise in the workplace), or as
environmental noise, which includes noise in all other settings, whether at the
community, residential, or domestic level (e.g. traffic, playgrounds, sports, music).
This guide concerns only occupational noise; the health effects of environmental noise
are covered in a separate publication (de Hollander et al., 2004).
High levels of occupational noise remain a problem in all regions of the world. exposed to hazardous noise (NIOSH, 1998). (12−15% of the workforce) are exposed to noise levels defined as hazardous by WHO
Although noise is associated with almost every work activity, some
activities are associated with particularly high levels of noise, the most important of
flying commercial jets. Occupations at highest risk for NIHL include those in
manufacturing, transportation, mining, construction, agriculture and the military.
The situation is improving in developed countries, as more widespread appreciation of
Data for developing
countries are scarce, but available evidence suggests that average noise levels are well
above the occupational level recommended in many developed nations (Suter, 2000;
The average noise levels in developing countries may be
There are therefore several reasons to assess the burden of disease from occupational
noise at country or subnational levels. Occupational noise is a widespread risk factor,
with a strong evidence base linking it to an important health outcome (hearing loss).
It is also distinct from environmental noise, in that it is by definition associated with
An assessment of the burden of disease associated with occupational noise can help
guide policy and focus research on this problem. occupational noise (WHO/FIOH, 2001).
2. The risk factor and its health outcomes
2.1 Measuring noise levels
There are a variety of metrics for quantifying noise levels, the most useful of which
for measuring sound as a health hazard is described in de Hollander et al. (2004). In
account for the sensitivity of people to noise. These corrections depend on the noise
frequency and characteristics (impulse, intermittent or continuous noise levels), and
the source of noise. The following measures are most relevant for assessing
occupational noise levels.
Sound pressure level. The sound pressure level (L) is a measure of the air vibrations
that make up sound. Because the human ear can detect a wide range of sound
pressure levels (from 20 μPa to 200 Pa), they are measured on a logarithmic scale
with units of decibels (dB) to indicate the loudness of a sound.
Sound level. frequencies. To account for the perceived loudness of a sound, a spectral sensitivity
factor is used to weight the sound pressure level at different frequencies (A-filter).
These A-weighted sound pressure levels are expressed in units of dB(A).
Equivalent sound levels. When sound levels fluctuate in time, which is often the case
for occupational noise, the equivalent sound level is determined over a specific time
period. In this guide, the A-weighted sound level is averaged over a period of time
A common exposure period, T, in occupational
studies and regulations is 8 h, and the parameter is designated by the symbol, LAeq,8h.
2.2 Disease outcomes related to the risk factor
In general, the health consequences of a given level of occupational noise are likely to
review has therefore been carried out of all well-designed epidemiological studies that
link occupational noise exposure to health outcomes, regardless of where the study
The review of the literature indicates that noise has a series of health effects, in
addition to hearing impairment (Table 1). with noise in the workplace. Other consequences of workplace noise, such as
annoyance, hypertension, disturbance of psychosocial well-being, and psychiatric
disorders have also been described (de Hollander et al., 2004).
For occupational noise, the best characterized health outcome is hearing impairment.
The first effects of exposure to excess noise are typically an increase in the threshold
of hearing (threshold shift), as assessed by audiometry. hearing thresholds of an average 10 dB or more at 2000, 3000 and 4000 Hz in either
ear (poorer hearing) (NIOSH, 1998). NIHL is measured by comparing the threshold
of hearing at a specified frequency with a specified standard of normal hearing, and is
reported in units of decibel hearing loss (dBHL).
Threshold shift is the precursor of NIHL, the main outcome of occupational noise. It
accompanied by tinnitus. Because hearing impairment is usually gradual, the affected
worker will not notice changes in hearing ability until a large threshold shift has
occurred. Noise-induced hearing impairment occurs predominantly at higher
frequencies (3000−6000 Hz), with the largest effect at 4000 Hz. increases in severity with continued exposure.
− social isolation;
− impaired communication with coworkers and family;
− decreased ability to monitor the work environment (warning signals, equipment
sounds);
− increased injuries from impaired communication and isolation;
− anxiety, irritability, decreased self-esteem;
− lost productivity;
− expenses for workers’ compensation and hearing aids.
2.3 The strength of the evidence for disease outcomes
The mechanisms linking occupational noise to the health outcomes described in the
countries or regions. strength of relationships, other studies are usually relevant for assessing the strength
of evidence for causality.
Evidence is usually assessed on the grounds of biological plausibility, strength and
consistency of association, independence of confounding variables and reversibility
(Hill, 1965). psychosocial well-being, psychiatric disorders, and effects on performance are
plausible outcomes, but are only weakly supported by epidemiological evidence.
Other plausible outcomes include biochemical effects, immune system effects, and
birth-weight effects, but again there is limited evidence to support these outcomes.
There is stronger evidence of noise-based annoyance, defined as “a feeling of
resentment, displeasure, discomfort, dissatisfaction or offence which occurs when
noise interferes with someone’s thoughts, feelings or daily activities” (Passchier-
Vermeer, 1993). Noise annoyance is always assessed at the level of populations,
There is consistent evidence for annoyance in populations
about 42 dB(A). doubt that annoyance from noise adversely affects human well-being.
A recent meta-analysis reviewed the effects of occupational and environmental noise
on a variety of cardiovascular risks, including hypertension, use of anti-hypertension
drugs, consultation with a general practitioner or specialist, use of cardiovascular
medicines, angina pectoris, myocardial infarction and prevalence of ischaemic heart
disease (van Kempen et al., 2002). The analysis showed an association with
hypertension, but only limited evidence for an association with the other health
outcomes. Reasons for the limited evidence included methodological weaknesses,
such as poor (retrospective) exposure assessment, poorly controlled confounding
variables, and selection bias (such as the “healthy worker” effect, where the studied
work through disability). individual studies, and summary relative risks were statistically significant in only a
limited number of cases. Overall, the causal link is plausible, and the meta-analysis
provides support for further investigation of cardiovascular effects in the future.
the meta-analysis. Global Burden of Disease study, and methods for estimating the cardiovascular
effects of noise were not defined (Concha-Barrientos et al., 2004). This guide does
not therefore provide information for assessing the cardiovascular effects of noise at
national or local levels. the physical properties of noise and damage to the hearing system). supported by epidemiological studies that compared the prevalence of hearing loss in
different categories of occupations, or in particularly noisy occupations (e.g. Arndt et
al., 1996; Waitzman & Smith, 1998; Hessel, 2000; Palmer, Pannett & Griffin, 2001).
The studies showed a strong association between occupational noise and NIHL, an
effect that increased with the duration and magnitude of the noise exposure. For
example, the risk for “blue-collar” construction workers was 2 to >3.5-fold greater
(Table 2). exposure to vibrations, ototoxic drugs and some chemicals, the association with
occupational noise remains robust after accounting for these influences. epidemiological evidence for an effect of high levels of occupational exposure on
hearing loss in unborn children (e.g. Lalande, Hetu & Lambert, 1986), but there was
Global Burden of Disease study, and it is not covered further in this guide.
3.4 Health outcomes to include in the burden of disease assessment
The selection of a health outcome should be made principally on the strength of the
evidence of causality and on the availability of information for quantifying health
impacts. It is also important that the health outcome has been assessed within the
study population, or can reasonably be extrapolated from other populations. several possible sources for health statistics, including national health statistics, a
national burden of disease study, or “prior estimates” provided by WHO. More
(Prüss-Üstün et al., 2003).
Depending on the aim of the study, it may be preferable to assess disease burden in
terms of attributable disease incidence, or overall disease burden, using summary
measures of population health such as DALYs (Murray, Salomon & Mathers, 2000).
with the health burden from other risk factors. A goal of burden of disease
assessments is to maximize the compatibility of frameworks for assessing the burden
of disease for risk factors. associated with each disease.
health outcomes often assessed in national health statistics and as part of WHO
burden of disease assessments. se. Should annoyance cause other health outcomes, such as hypertension and
associated cardiovascular disease, then other outcomes could be considered. comparative disability weights independently, to take them from other studies (e.g. de
Hollander et al., 2004), or to extrapolate them from similar health outcomes. You
should be aware that an independent assessment of the severity of such outcomes
introduces additional uncertainty when the results are compared with other risk factors
This guide follows the previous global assessment of occupational noise, in that only
the effects of occupational noise on NIHL are assessed. Several definitions of hearing
impairment are available in the literature. In the occupational setting, hearing
impairment is generally defined as “ a binaural pure-tone average for the frequencies
Sriwattanatamma & Breysse, 2000). correspond to the WHO definition of disabling hearing loss (i.e. with an associated
disability weight, and corresponding to a quantifiable burden of disease). This level
of hearing impairment is defined as “permanent unaided hearing threshold level for
4000 kHz” (Table 3). prevalence of hearing loss that corresponds to the WHO definition, as it is preferable
for burden of disease assessments. procedure is supported by large epidemiological studies, and should therefore
readmore»
Thursday, April 8, 2010
air pollution causes
There are many different chemical substances that contribute to air pollution. Among the many types of air pollutants are nitrogen oxides, carbon monoxides, and organic compounds that can evaporate and enter the atmosphere.
Air pollutants have sources that are both natural and human. Now, humans contribute substantially more to the air pollution problem.
Forest fires, volcanic eruptions, wind erosion, pollen dispersal, evaporation of organic compounds, and natural radioactivity are all among the natural causes of air pollution.
Usually, natural air pollution does not occur in abundance in particular locations. Though some pollution comes from these natural sources, most pollution is the result of human activity. The biggest causes are the operation of fossil fuel-burning power plants and automobiles that combust fuel. Combined, these two sources are responsible for about 90% of all air pollution in the United States.
Some cities suffer severely because of heavy industrial use of chemicals that cause air pollution. Places like Mexico City and Sao Paulo have some of the most deadly pollution levels in the world
Air pollutants have sources that are both natural and human. Now, humans contribute substantially more to the air pollution problem.
Forest fires, volcanic eruptions, wind erosion, pollen dispersal, evaporation of organic compounds, and natural radioactivity are all among the natural causes of air pollution.
Usually, natural air pollution does not occur in abundance in particular locations. Though some pollution comes from these natural sources, most pollution is the result of human activity. The biggest causes are the operation of fossil fuel-burning power plants and automobiles that combust fuel. Combined, these two sources are responsible for about 90% of all air pollution in the United States.
Some cities suffer severely because of heavy industrial use of chemicals that cause air pollution. Places like Mexico City and Sao Paulo have some of the most deadly pollution levels in the world
readmore»
Air pollution
Every day, the average person inhales about 20,000 liters of air. Every time we breathe, we risk inhaling dangerous chemicals that have found their way into the air.
Air pollution includes all contaminants found in the atmosphere. Air pollution can be found both outdoors and indoors. Pollutants can be trapped inside buildings, causing indoor pollution that lasts for a long time.
The sources of air pollution are both natural and human-based. Air pollution has been a problem throughout history. Even in Ancient Rome people complained about smoke put into the atmosphere.
The effects of air pollution are diverse and numerous. Air pollution can have serious consequences for the health of human beings, and also severely affects natural ecosystems.
Because it is located in the atmosphere, air pollution is able to travel easily. As a result, air pollution is a global problem and has been the subject of global cooperation and conflict.
Some areas now suffer more than others from air pollution. Cities with large numbers of automobiles or those that use great quantities of coal often suffer most severely from problems of air pollution.
Air pollution includes all contaminants found in the atmosphere. Air pollution can be found both outdoors and indoors. Pollutants can be trapped inside buildings, causing indoor pollution that lasts for a long time.
The sources of air pollution are both natural and human-based. Air pollution has been a problem throughout history. Even in Ancient Rome people complained about smoke put into the atmosphere.
The effects of air pollution are diverse and numerous. Air pollution can have serious consequences for the health of human beings, and also severely affects natural ecosystems.
Because it is located in the atmosphere, air pollution is able to travel easily. As a result, air pollution is a global problem and has been the subject of global cooperation and conflict.
Some areas now suffer more than others from air pollution. Cities with large numbers of automobiles or those that use great quantities of coal often suffer most severely from problems of air pollution.
readmore»
Monday, April 5, 2010
various Type of Pollution
Sound Pollution
Noise, by definition, is unwanted sound. The natural environment contains many sources of noise - wind, volcanoes, oceans, and animal sounds are all familiar intrusions accepted at various levels. Man-made noises - from machines, automobiles, trains, planes, explosives and firecrackers, etc. - are more contentious. Both kinds of noise affect sleep, hearing, communication, as well as mental and physical health
Pollution is a noun derived from the verb pollute, meaning: to foul. It is now increasingly understood that pollution from noise is an important component of air pollution, which was previously understood as being limited to material pollution. Noise is an inescapable by-product of the industrial environment, which is increasing with advances in industrialization and urbanization. Continuous noise causes an increase in the cholesterol level resulting in permanent constriction of blood vessels, making one prone to heart attacks and strokes. Health experts are of the opinion that excessive noise can also lead to neurosis and nervous breakdown.
Noise travels through air and hence it is measured in ambient air quality level. Noise is measured in decibels. Experts believe that continuous noise levels in excess of 90 decibels can cause loss of hearing and irreversible changes in nervous systems. The World Health Organization [WHO] has fixed 45 decibels as the safe noise level for a city.
Waste and Water Pollution
When toxic substances enter lakes, streams, rivers, oceans, and other water bodies, they get dissolved or lie suspended in water or get deposited on the bed. This results in the pollution of water whereby the quality of the water deteriorates, affecting aquatic ecosystems. Pollutants can also seep down and affect the groundwater deposits.
Today, many people dump their garbage into streams, lakes, rivers, and seas, thus making water bodies the final resting place of cans, bottles, plastics, and other household products. The various substances that we use for keeping our houses clean add to water pollution as they contain harmful chemicals. In the past, people mostly used soaps made from animal and vegetable fat for all types of washing. But most of today’s cleaning products are synthetic detergents and come from the petrochemical industry. Most detergents and washing powders contain phosphates, which are used to soften the water among other things. These and other chemicals contained in washing powders affect the health of all forms of life in the water.
The effects of water pollution are not only devastating to people but also to animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It diminishes the aesthetic quality of lakes and rivers. More seriously, contaminated water destroys aquatic life and reduces its reproductive ability. Eventually, it is a hazard to human health. Nobody can escape the effects of water pollution
Air Pollution
It is the contamination of air by the discharge of harmful substances. Air pollution can cause health problems and it can also damage the environment and property. Industries, vehicles, increase in the population, and urbanization are some of the major factors responsible for air pollution. The following industries are among those that emit a great deal of pollutants into the air: thermal power plants, cement, steel, refineries, petro chemicals, and mines.
Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert areas and smoke from forest fires and grass fires contribute to chemical and particulate pollution of the air. The source of pollution may be in one country but the impact of pollution may be felt elsewhere. Listed below are the major air pollutants and their sources.
Carbon monoxide (CO) is a colourless, odourless gas that is produced by the incomplete burning of carbon-based fuels including petrol, diesel, and wood. Carbon dioxide (CO2) is the principle greenhouse gas emitted as a result of human activities such as the burning of coal, oil, and natural gases.
Chloroflorocarbons (CFC) are gases that are released mainly from air-conditioning systems and refrigeration. Lead is present in petrol, diesel, lead batteries, paints, hair dye products, etc. Lead affects children in particular. It can cause nervous system damage and digestive problems and, in some cases, cause cancer.
Ozone occur naturally in the upper layers of the atmosphere. This important gas shields the earth from the harmful ultraviolet rays of the sun. However, at the ground level, it is a pollutant with highly toxic effects. Vehicles and industries are the major source of ground-level ozone emissions. Ozone makes our eyes itch, burn, and water. It lowers our resistance to colds and pneumonia.
Nitrogen oxide (Nox) causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal. Nitrogen oxides can make children susceptible to respiratory diseases in winters.
Suspended particulate matter (SPM) consists of solids in the air in the form of smoke, dust, and vapour that can remain suspended for extended periods and is also the main source of haze which reduces visibility. The finer of these particles, when breathed in can lodge in our lungs and cause lung damage and respiratory problems.
Sulphur dioxide (SO2) is a gas produced from burning coal, mainly in thermal power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide. Sulfur dioxide can lead to lung diseases.
Chemical Pollution
There are many different sources of chemical pollution, including:
• domestic sewage
• industrial discharges
• seepage from waste sites
• atmospheric fallout
• domestic run-off
• accidents and spills at sea
• operational discharges from oil rigs
• mining discharges and
• agricultural run-off.
However, the chemicals that are probably of most concern for everyone are the persistent pollutants: those substances that enter marine food chains and are eventually passed along the chain to the marine top predators in increasing amounts.Persistent pollutants include pesticides, such as DDT, and industrial chemicals, most famously the PCBs.
When toxic substances enter lakes, streams, rivers, oceans, and other water bodies, they get dissolved or lie suspended in water or get deposited on the bed. This results in the pollution of water whereby the quality of the water deteriorates, affecting aquatic ecosystems. Pollutants can also seep down and affect the groundwater deposits.
Today, many people dump their garbage into streams, lakes, rivers, and seas, thus making water bodies the final resting place of cans, bottles, plastics, and other household products. The various substances that we use for keeping our houses clean add to water pollution as they contain harmful chemicals. In the past, people mostly used soaps made from animal and vegetable fat for all types of washing. But most of today’s cleaning products are synthetic detergents and come from the petrochemical industry. Most detergents and washing powders contain phosphates, which are used to soften the water among other things. These and other chemicals contained in washing powders affect the health of all forms of life in the water.
The effects of water pollution are not only devastating to people but also to animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It diminishes the aesthetic quality of lakes and rivers. More seriously, contaminated water destroys aquatic life and reduces its reproductive ability. Eventually, it is a hazard to human health. Nobody can escape the effects of water pollution
Air Pollution
It is the contamination of air by the discharge of harmful substances. Air pollution can cause health problems and it can also damage the environment and property. Industries, vehicles, increase in the population, and urbanization are some of the major factors responsible for air pollution. The following industries are among those that emit a great deal of pollutants into the air: thermal power plants, cement, steel, refineries, petro chemicals, and mines.
Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert areas and smoke from forest fires and grass fires contribute to chemical and particulate pollution of the air. The source of pollution may be in one country but the impact of pollution may be felt elsewhere. Listed below are the major air pollutants and their sources.
Carbon monoxide (CO) is a colourless, odourless gas that is produced by the incomplete burning of carbon-based fuels including petrol, diesel, and wood. Carbon dioxide (CO2) is the principle greenhouse gas emitted as a result of human activities such as the burning of coal, oil, and natural gases.
Chloroflorocarbons (CFC) are gases that are released mainly from air-conditioning systems and refrigeration. Lead is present in petrol, diesel, lead batteries, paints, hair dye products, etc. Lead affects children in particular. It can cause nervous system damage and digestive problems and, in some cases, cause cancer.
Ozone occur naturally in the upper layers of the atmosphere. This important gas shields the earth from the harmful ultraviolet rays of the sun. However, at the ground level, it is a pollutant with highly toxic effects. Vehicles and industries are the major source of ground-level ozone emissions. Ozone makes our eyes itch, burn, and water. It lowers our resistance to colds and pneumonia.
Nitrogen oxide (Nox) causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal. Nitrogen oxides can make children susceptible to respiratory diseases in winters.
Suspended particulate matter (SPM) consists of solids in the air in the form of smoke, dust, and vapour that can remain suspended for extended periods and is also the main source of haze which reduces visibility. The finer of these particles, when breathed in can lodge in our lungs and cause lung damage and respiratory problems.
Sulphur dioxide (SO2) is a gas produced from burning coal, mainly in thermal power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide. Sulfur dioxide can lead to lung diseases.
Chemical Pollution
There are many different sources of chemical pollution, including:
• domestic sewage
• industrial discharges
• seepage from waste sites
• atmospheric fallout
• domestic run-off
• accidents and spills at sea
• operational discharges from oil rigs
• mining discharges and
• agricultural run-off.
However, the chemicals that are probably of most concern for everyone are the persistent pollutants: those substances that enter marine food chains and are eventually passed along the chain to the marine top predators in increasing amounts.Persistent pollutants include pesticides, such as DDT, and industrial chemicals, most famously the PCBs.
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Noise pollution
Noise pollution is a type of energy pollution in which distracting, irritating, or damaging sounds are freely audible. As with other forms of energy pollution (such as heat and light pollution), noise pollution contaminants are not physical particles, but rather waves that interfere with naturally-occurring waves of a similar type in the same environment. Thus, the definition of noise pollution is open to debate, and there is no clear border as to which sounds may constitute noise pollution. In the most narrow sense, sounds are considered noise pollution if they adversely affect wildlife, human activity, or are capable of damaging physical structures on a regular, repeating basis. In the broadest sense of the term, a sound may be considered noise pollution if it disturbs any natural process or causes human harm, even if the sound does not occur on a regular basis.
The prevailing source of artificial noise pollution is from transportation. In rural areas, train and airplane noise can disturb wildlife habits, thereby affecting the manner in which animals in areas around train tracks and airports hunt and mate. In urban areas, automobile, motorcycle, and even entertainment noise can cause sleep disruption in humans and animals, hearing loss, heart disease (as a result of stress), and in severe cases even mental instability. A notable exception to the rule is the electric, or hybrid-electric, automobile. Although most developed nations have government agencies responsible for the protection of the environment, no nation has a single body that regulates noise pollution. In the United States, Canada, Europe, and most other developed parts of the world, different types of noise are managed by agencies responsible for the source of the noise. Transportation noise is usually regulated by the relevant transportation ministry, health-related work noise is often regulated by health ministries and worker's unions, and entertainment noise such as loud music is a criminal offense in many areas. As the bodies responsible for noise pollution reduction usually view noise as an annoyance rather than a problem, and reducing that noise often hurts the industry financially, little is currently being done to reduce noise pollution in developed countries.
The prevailing source of artificial noise pollution is from transportation. In rural areas, train and airplane noise can disturb wildlife habits, thereby affecting the manner in which animals in areas around train tracks and airports hunt and mate. In urban areas, automobile, motorcycle, and even entertainment noise can cause sleep disruption in humans and animals, hearing loss, heart disease (as a result of stress), and in severe cases even mental instability. A notable exception to the rule is the electric, or hybrid-electric, automobile. Although most developed nations have government agencies responsible for the protection of the environment, no nation has a single body that regulates noise pollution. In the United States, Canada, Europe, and most other developed parts of the world, different types of noise are managed by agencies responsible for the source of the noise. Transportation noise is usually regulated by the relevant transportation ministry, health-related work noise is often regulated by health ministries and worker's unions, and entertainment noise such as loud music is a criminal offense in many areas. As the bodies responsible for noise pollution reduction usually view noise as an annoyance rather than a problem, and reducing that noise often hurts the industry financially, little is currently being done to reduce noise pollution in developed countries.
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