Kamil Hafidh
2005-08-11 13:31:02 UTC
What is Haze?
The haze we see in our city skyline is caused by tiny particulates suspended
in the atmosphere. At high concentrations, these particulates scatter and
absorb sunlight resulting in diminished horizontal visibility thereby giving
the atmosphere a characteristic opalescent appearance. Haze is not confined
to urban environments, it may also be observed in rural areas.
Haze Particles - Their Origin
The particles that cause the haze phenomenon can originate from many
sources, some of which are natural and some anthropogenic. Natural sources
include the oceans, forests and ground surface. However the majority of the
particulates are from human activities which include open burning, land
clearing, vehicular use and combustion of fossil fuels in industrial
boilers.
Atmospheric Conditions That Favour Haze Formation
In the tropics, wind speeds are generally low. During certain periods of the
year, particularly during the Southwest Monsoon season, the atmosphere is
very stable and horizontal as well as vertical air movements are reduced.
The subsiding air mass does not favour active cloud development, thus the
weather is dry. Several factors such as prolonged dry weather, a stable
atmosphere, and an abundant supply of pollutants from urban or rural sources
are the ideal ingredients for the formation of haze. Particulates emitted
into the atmosphere are trapped within the stagnant air mass causing the
particulate concentration to increase thus producing a hazy condition. In
Peninsular Malaysia, haze is most likely to occur during the months from
January to February and June to August.
On the other hand, during the Northeast Monsoon season, the moisture-rich
northeasterly winds blowing from the South China Sea are generally stronger
and therefore more effective in dispersing haze pollutants. The Northeast
Monsoon is often associated with more frequent widespread rain, thus haze is
seldom observed.
What Causes The Haze To Clear?
In our changing atmosphere, just as there are hazy days, there are also days
which are clear and clean. What can bring about this change? Particulates in
the atmosphere are removed through several processes. A proportion,
particularly the heavier particles, settle to the ground or onto surfaces by
gravitational sedimentation.
The finer particles are removed by a process called "rainout" involving
condensation of water vapour ontominute particles to form water droplets
eventually producing clouds.Particles are also removed below cloud by
collision and adhesion with falling raindrops through another process called
"washout".
Yet another removal mechanism involves the role of turbulence in
transporting the haze particulates up to the higher levels of the atmosphere
for more effective dispersion. In this case, widespread heavy
rain/thunderstorms with strong updrafts and downdrafts are more effective,
whereas light rain showers of short duration are usually quite infficient in
cleansing the atmosphere in a severe haze situation.
Haze, Mist or Fog ?
Often, haze is confused with mist and fog. During the early morning or after
rain showers when temperatures are low and humidity is high, mist and
sometimes fog forms in valleys and lowlands, gradually clearing when the sun
reappears. Mist and fog are formed as a result of the condensation of water
vapour on particulates suspended in the atmosphere. Meteorologically, mist
is defined as being present if diminished visibility occurs (with no other
weather condition being present) and relative humidity of the atmosphere at
the surface of the earth is above 95%. When the horizontal visibility falls
below 1000 metres the phenomena is classified as fog.
Is Haze Harmful ?
Haze originating from natural sources such as sea salt and soildust is
generally harmless to humans. Slight, transient haze visible in most towns
and cities has not been proven to cause any serious long-term health effects
on the population. However, during a severe haze episode, prolonged exposure
to high concentrations of particulates can be harmful to health. Associated
with previous haze episodes, there have been reports of increases in
incidences of eye and throat irritations and respiratory difficulties among
sensitive groups. During a haze episode, the public are strongly urged to
follow the advice issued by the local health authorities.
How Can We Reduce The Incidence Of Haze?
Firstly, we should refrain from open burning of waste. Most incidences of
local haze can be traced to this activity. Motor vehicles, due to their
increasing numbers, are also major sources of haze particulates in urban
areas. To reduce haze, vehicles should be well maintained. Choose fuels
which are the least polluting. Large scale land clearing which exposes large
tracts of barren land, not only results in soil erosion and degradation, but
also provides a source of particulates to the atmosphere. Promoting efforts
such as rapid replanting and staggered land clearing can reduce haze.
Remember that every individual has a role to play to preserve the quality of
our environment as a legacy for our future generations.
What Is The Government's Role?
The two Federal agencies directly involved with matters relating to haze are
the Department of Environment (DOE) and the Malaysian Meteorological Service
(MMS), which are under the Ministry of Science, Technology and the
Environment. MMS monitors atmospheric conditions related to weather as well
as some parameters relating to the ambient air quality. One of the
parameters measured is suspended particulate (TSP) concentration in air
which is directly related to haze intensity. Other meteorological parameters
such as horizontal visibility, relative humidity and wind velocity are
useful indicators in understanding the haze phenomenon and forecasting its
occurrence and dispersal. The monitoring and research activities conducted
by MMS is part of the national effort to control and mitigate haze.
Close cooperation among all related government agencies, local authorities
and the mass media are essential during a haze episode to ensure all
necessary data required for decision making is acquired, and any advice is
rapidly disseminated to the public. At the regional level, ASEAN has
initiated an ASEAN Cooperation Plan on the Management of Transboundary
Pollution to address issues such as transboundary haze.
Regards,
Kamil Hafidh Halim
http://www.cybershop2u.net?member=skywalker
The haze we see in our city skyline is caused by tiny particulates suspended
in the atmosphere. At high concentrations, these particulates scatter and
absorb sunlight resulting in diminished horizontal visibility thereby giving
the atmosphere a characteristic opalescent appearance. Haze is not confined
to urban environments, it may also be observed in rural areas.
Haze Particles - Their Origin
The particles that cause the haze phenomenon can originate from many
sources, some of which are natural and some anthropogenic. Natural sources
include the oceans, forests and ground surface. However the majority of the
particulates are from human activities which include open burning, land
clearing, vehicular use and combustion of fossil fuels in industrial
boilers.
Atmospheric Conditions That Favour Haze Formation
In the tropics, wind speeds are generally low. During certain periods of the
year, particularly during the Southwest Monsoon season, the atmosphere is
very stable and horizontal as well as vertical air movements are reduced.
The subsiding air mass does not favour active cloud development, thus the
weather is dry. Several factors such as prolonged dry weather, a stable
atmosphere, and an abundant supply of pollutants from urban or rural sources
are the ideal ingredients for the formation of haze. Particulates emitted
into the atmosphere are trapped within the stagnant air mass causing the
particulate concentration to increase thus producing a hazy condition. In
Peninsular Malaysia, haze is most likely to occur during the months from
January to February and June to August.
On the other hand, during the Northeast Monsoon season, the moisture-rich
northeasterly winds blowing from the South China Sea are generally stronger
and therefore more effective in dispersing haze pollutants. The Northeast
Monsoon is often associated with more frequent widespread rain, thus haze is
seldom observed.
What Causes The Haze To Clear?
In our changing atmosphere, just as there are hazy days, there are also days
which are clear and clean. What can bring about this change? Particulates in
the atmosphere are removed through several processes. A proportion,
particularly the heavier particles, settle to the ground or onto surfaces by
gravitational sedimentation.
The finer particles are removed by a process called "rainout" involving
condensation of water vapour ontominute particles to form water droplets
eventually producing clouds.Particles are also removed below cloud by
collision and adhesion with falling raindrops through another process called
"washout".
Yet another removal mechanism involves the role of turbulence in
transporting the haze particulates up to the higher levels of the atmosphere
for more effective dispersion. In this case, widespread heavy
rain/thunderstorms with strong updrafts and downdrafts are more effective,
whereas light rain showers of short duration are usually quite infficient in
cleansing the atmosphere in a severe haze situation.
Haze, Mist or Fog ?
Often, haze is confused with mist and fog. During the early morning or after
rain showers when temperatures are low and humidity is high, mist and
sometimes fog forms in valleys and lowlands, gradually clearing when the sun
reappears. Mist and fog are formed as a result of the condensation of water
vapour on particulates suspended in the atmosphere. Meteorologically, mist
is defined as being present if diminished visibility occurs (with no other
weather condition being present) and relative humidity of the atmosphere at
the surface of the earth is above 95%. When the horizontal visibility falls
below 1000 metres the phenomena is classified as fog.
Is Haze Harmful ?
Haze originating from natural sources such as sea salt and soildust is
generally harmless to humans. Slight, transient haze visible in most towns
and cities has not been proven to cause any serious long-term health effects
on the population. However, during a severe haze episode, prolonged exposure
to high concentrations of particulates can be harmful to health. Associated
with previous haze episodes, there have been reports of increases in
incidences of eye and throat irritations and respiratory difficulties among
sensitive groups. During a haze episode, the public are strongly urged to
follow the advice issued by the local health authorities.
How Can We Reduce The Incidence Of Haze?
Firstly, we should refrain from open burning of waste. Most incidences of
local haze can be traced to this activity. Motor vehicles, due to their
increasing numbers, are also major sources of haze particulates in urban
areas. To reduce haze, vehicles should be well maintained. Choose fuels
which are the least polluting. Large scale land clearing which exposes large
tracts of barren land, not only results in soil erosion and degradation, but
also provides a source of particulates to the atmosphere. Promoting efforts
such as rapid replanting and staggered land clearing can reduce haze.
Remember that every individual has a role to play to preserve the quality of
our environment as a legacy for our future generations.
What Is The Government's Role?
The two Federal agencies directly involved with matters relating to haze are
the Department of Environment (DOE) and the Malaysian Meteorological Service
(MMS), which are under the Ministry of Science, Technology and the
Environment. MMS monitors atmospheric conditions related to weather as well
as some parameters relating to the ambient air quality. One of the
parameters measured is suspended particulate (TSP) concentration in air
which is directly related to haze intensity. Other meteorological parameters
such as horizontal visibility, relative humidity and wind velocity are
useful indicators in understanding the haze phenomenon and forecasting its
occurrence and dispersal. The monitoring and research activities conducted
by MMS is part of the national effort to control and mitigate haze.
Close cooperation among all related government agencies, local authorities
and the mass media are essential during a haze episode to ensure all
necessary data required for decision making is acquired, and any advice is
rapidly disseminated to the public. At the regional level, ASEAN has
initiated an ASEAN Cooperation Plan on the Management of Transboundary
Pollution to address issues such as transboundary haze.
Regards,
Kamil Hafidh Halim
http://www.cybershop2u.net?member=skywalker