ایمنی، بهداشت، محیط زیست
گوناگون از ایمنی، بهداشت و محیط زیست
Portland cement is one of the most widely used materials in
construction. Applications include concrete floors, walls, and pavement;
concrete blocks; and different mixtures of mortar and grout. Thousands of construction workers are exposed to concrete every day
without harm. But anyone who uses or supervises the use of portland cement
should know its health hazards and the safe working procedures necessary to
minimize exposure. This article outlines those hazards and makes
recommendations on how to use cement safely. Waterproof rubber boots are essential in working with wet concrete Health effects Cement can cause ill health by skin contact, eye contact, or inhalation.
Risk of injury depends on duration and level of exposure and individual
sensitivity. Hazardous materials in wet concrete and mortar include: * alkaline
compounds such as lime (calcium oxide) that are corrosive to human tissue * trace amounts of crystalline
silica which is abrasive to the skin and can damage lungs * trace amounts of chromium that can
cause allergic reactions. Skin contact The hazards of wet cement are due to its caustic, abrasive, and drying
properties. Wet concrete contacting the skin for a short period and then thoroughly
washed off causes little irritation. But continuous contact between skin and
wet concrete allows alkaline compounds to penetrate and burn the skin. When wet concrete or mortar is trapped against the skin—for instance, by
falling inside a worker’s boots or gloves or by soaking through protective
clothing—the result may be first, second, or third degree burns or skin ulcers.
These injuries can take several months to heal and may involve hospitalization
and skin grafts. First degree burn - outer skin layer Second degree burn - middle skin layer Third degree burn - deep skin layer Ironically, severe cases often occur when personal protective clothing
or equipment is worn. Wet concrete may get trapped inside rubber boots or
gloves or gradually soak through coveralls. Concrete finishers kneeling on
fresh concrete have had their knees severely burned. Corrosive bleed water from
the concrete is absorbed by the worker’s pants and held against the skin for
prolonged periods. Without waterproof knee pads, kneeling on wet concrete can irritate or
burn the skin Cement dust released during bag dumping or concrete cutting can also
irritate the skin. Moisture from sweat or wet clothing reacts with the cement
dust to form a caustic solution. Allergic skin reaction Some workers become allergic to the hexavalent chromium in cement. A
small yet significant percentage of all workers using cement will develop an
allergy to chromium, with symptoms ranging from a mild rash to severe skin
ulcers. In addition to skin reactions, hexavalent chromium can cause a
respiratory allergy called occupational asthma. Symptoms include wheezing and
difficulty breathing. Workers may develop both skin and respiratory allergies
to hexavalent chromium. It’s possible to work with cement for years without any allergic skin
reaction and then to suddenly develop such a reaction. The condition gets worse
until exposure to even minute quantities triggers a severe reaction. The
allergy usually lasts a lifetime and prevents any future work with wet concrete
or powder cement. Eye contact Exposure to airborne dust may cause immediate or delayed irritation of
the eyes. Depending on the level of exposure, effects may range from redness to
chemical burns and blindness. Inhalation Inhaling high levels of dust may occur when workers empty bags of
cement. In the short term, such exposure irritates the nose and throat and
causes choking and difficult breathing. Sanding, grinding, or cutting concrete
can also release large amounts of dust containing high levels of crystalline
silica. Prolonged or repeated exposure can lead to a disabling and often fatal
lung disease called silicosis. Some studies also indicate a link between
crystalline silica exposure and lung cancer. Dry cutting generates high levels of dust Controls The following are some basic recommendations for handling and using
cement safely. Personal protection To protect skin from cement and cement mixtures, workers should wear: * alkali-resistant
gloves * coveralls with long sleeves and
full-length trousers (pull sleeves down over gloves and tuck pants inside boots
and duct-tape at the top to keep mortar and concrete out) * waterproof boots high enough to
prevent concrete from flowing in when workers must stand in fresh concrete * suitable respiratory protective
equipment such as a P, N or R 95 respirator when cement dust can’t be avoided * suitable eye protection where
mixing, pouring, or other activities may endanger eyes (minimum—safety glasses
with sideshields or goggles, under extremely dusty conditions, tight-fitting
unvented or indirectly vented goggles. Don’t wear contact lenses when handling
cement or cement products). Work practices * When
laying concrete block, have different sizes on hand to avoid cutting or
hammering to make them fit. * Work in ways that minimize the
amount of cement dust released. * Where possible, wet-cut rather
than dry-cut masonry products. * Mix dry cement in well-ventilated
areas. * Make sure to work upwind from dust
sources. * Where possible, use ready-mixed
concrete instead of mixing on site. * When kneeling on fresh concrete,
use a dry board or waterproof kneepads to protect knees from water that can
soak through fabric. * Remove jewelry such as rings and
watches because wet cement can collect under them. Hygiene * Clothing
contaminated by wet cement should be quickly removed. Skin in contact with wet
cement should be washed immediately with large amounts of cool clean water. * Don’t wash your hands with water
from buckets used for cleaning tools. * Provide adequate hygiene
facilities on site for workers to wash hands and face at the end of a job and
before eating, drinking, smoking, or using the toilet. Facilities for cleaning
boots and changing clothes should also be available. Training Under the Workplace Hazardous Materials Information System (WHMIS) in
force across Canada, workers handling, using, or exposed to dry or wet cement
must be educated in hazards and controls. First aid Skin contaminated with wet or dry cement should be washed with cold
running water as soon as possible. Open sores or cuts should be thoroughly
flushed and covered with suitable dressings. Get medical attention if
discomfort persists. Contaminated eyes should be washed with cold tap water for
at least 15 minutes before the affected person is taken to hospital. References Health and Safety Executive, Cement, Construction Information Sheet No
26 (revised) Portland Cement Association, Skin Safety with Cement and Concrete,
videotape This paper appears in the eLCOSH website with the permission of the
author and/or copyright holder and may not be reproduced without their consent.
eLCOSH is an information clearinghouse. eLCOSH and its sponsors are not responsible
for the accuracy of information provided on this web site, nor for its use or
misuse. Portland
cement is one of the most widely used materials in
construction. Thousands of workers are exposed to concrete every day
without harm, but anyone who uses portland cement
should be aware of the safe working practices necessary to
minimize exposure and injury. The most
common types of health hazards resulting from exposure to
portland cement involve skin contact, eye contact and
inhalation. Wet concrete contacting the skin for a short period
and then thoroughly washed off causes little irritation,
but continuous contact between skin and wet concrete
allows alkaline compounds to penetrate and burn the skin
which can result in first, second or third degree burns or
skin ulcers. These injuries can take several months to
heal and may involve hospitalization and skin grafts. The
following are some basic recommendations for handling and using
cement safely: Personal
Protective Equipment: To protect skin from
cement and cement mixtures, workers should wear
alkali-resistant gloves; coveralls with long sleeves and
full-length pants; waterproof boots high enough to prevent
concrete from flowing in; suitable respiratory protective equipment
such as a P, N or R 95 respirator when exposed to
cement dust; and suitable eye protection (as a minimum,
safety glasses with side shields) where mixing, pouring or
other activities may endanger the eyes. Don’t wear contact
lenses when handling cement or cement products. Work
Practices: When laying concrete block, have different
sizes on hand to minimize cutting and hammering. Work in ways
that minimize the amount of cement dust
released. Where possible, wet-cut rather than drycut masonry
products. Mix dry cement in well-ventilated areas. Make
sure to work upwind from dust sources. Use ready-mix
concrete instead of mixing on site. When kneeling on fresh
concrete, use a dry board or waterproof knee pads to
protect knees from caustic water. Remove jewelry such as
rings and watches, to avoid cement collecting under them. Hygiene: Clothing contaminated by wet cement should be quickly
removed. Skin in contact with wet cement should be
washed immediately with large amounts of clean water. Don’t
wash hands in water from buckets used for cleaning
tools. Provide adequate hygiene facilities on site for workers
to wash their hands and face at the end of a job and
before eating, drinking, smoking or using the toilet. Washing
facilities must be close enough so as to encourage
their use by employees. Training: Under the Hazard Communication Standard, employees
who handle, use or are otherwise exposed to dry or wet
cement must be educated in the hazards of the products and
the control methods used to minimize exposure and
potential for injury. First
Aid: Skin contaminated with wet or dry
cement should be
washed with cold running water as soon as possible. Open sores
or cuts should be thoroughly flushed and covered
with suitable dressings. Get medical attention if
discomfort persists. Contaminated eyes should be washed with
cold tap water for at least 15 minutes before the affected
person is taken to medical attention. precaution that may be taken to ensure the safety of children who might be tempted to gain unauthorised access to a construction site 1. Fencing 2. security 3. Camera 4. Warning signs 5. Visit schools 6. Take children to site on visits 7. Lock away vehicle keys 8. Lock away hazardous chemicals 9. Cover holes 10. Remove ladders 11. Reduce heights of materials - در محل نگهداری سیلندرها می بایست علامت هشدار دهنده "انجام کار گرم ممنوع" نصب گردد.![]()
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