Performing tasks at a computer workstation involves repeating the same types of motions
over and over again. These types of repetitive motions put stress on muscles, tendons,
ligaments and joints. Prolonged repetitive motion stress can result in repetitive
motion injuries. In addition, continuous sitting at a computer workstation can cause
pressure on the discs between the vertebra of the back and pooling of blood in the
legs. This safety note provides information to reduce the potential for repetitive
motion injuries and increase comfort while sitting for long periods of time.
Recommended Computer Workstation Practices
Adjust chair height so that feet are flat on the floor or footrest at about shoulder
- Sit straight in chair with lower back firmly supported against the backrest. The upper
back should be lightly touching the backrest.
- Position the computer monitor so it is at a distance of about 24 inches from the user
and away from lighting that causes screen glare.
- The computer monitor should be located in front of the keyboard and user.
- The top of the computer monitor screen should be at eye level when the user is sitting
upright. Users that wear bifocals should position the computer screen slightly lower.
- The keyboard should be located close to the computer user and at a height whereby
the user’s shoulders remain relaxed and forearms are parallel to the floor. The bottom
of the user’s elbows should be at the same height as the keyboard.
- The mouse should be located adjacent to the keyboard on the same surface.
- Movement of a mouse should alternately take place from the both the shoulder and wrist.
- When typing, the wrists should remain straight. If necessary, use a padded wrist rest
to maintain a straight wrist position.
- While typing, fingers, hands, wrists, arms, and shoulders should be relaxed.
- Locate work materials in front of the computer user. If necessary, employ a document
holder to position work materials in front of the user.
- Frequently change body positions and take short stretch breaks every 30 minutes.
- Rest the eyes hourly by looking away from the monitor and focusing on distant objects.
- Intersperse other work activities with computer typing tasks, especially those that
allow the worker to leave their chair and stand or walk.
The dangers of canned air
Canned air is commonly used in offices to clean dust from equipment such as computers
and shredders. These products often are used without incident; however, lack of training
in proper use can lead to flash fires and injuries, warns the Washington State Department
of Labor and Industries.
Canned air is different from the air we breathe. The products are made of a gas that
is compressed into a liquid and canned. The types of gases used vary, and some are
dangerous when used improperly. Some of the more common dangers include:
- Flammable ingredients. When canned gas is tilted, the liquefied and highly flammable gas can be released
into the air and onto surfaces it contacts. This can be especially dangerous in poorly
ventilated areas. When a flammable atmosphere is created, flames, sparks and electrical
switches can ignite the concentrated gas, causing a flash fire.
- Frostbite. The liquid inside canned air can cause frostbite when the skin is exposed to a steady
stream. This can vary from an intense burning sensation to serious physical injuries
such as skin cracking, and damage to muscles, blood vessels and nerves.
- Asphyxiation and toxicity. When high concentrations of the gas are released into a nonventilated area, oxygen
deficiency and possible asphyxiation can occur. The effects of inhalation vary depending
on the type of chemical used, as well as the intensity and duration of exposure. When
used properly, a serious breathing problem is unlikely to occur.
Simple steps in the workplace can help keep workers safe from these dangers associated
with canned air products. Washington L&I recommends the following measures:
- Find out who uses canned air and in what areas of the workplace it is used.
- Determine whether the areas are properly ventilated. If they are not, move use to
an open and well-ventilated area.
- Check the contents of the canned air products in use at your workplace. If the product
is flammable, switch to a nonflammable alternative.
- Consider whether the use of eye, face and skin protection is needed when using canned
- Make sure all canned air users – and those in charge of purchasing – are aware of
potential hazards associated with use of the products.
- Make sure users read the label on the can and follow all instructions for proper use.
- Keep Material Safety Data Sheets available for complete information.
Canned-air products commonly are used in offices to remove dust from computers, shredders
and other electronic equipment. The Washington State Department of Labor and Industries
warns employers that without proper training, employees may not follow safe practices
because they assume the products are harmless. However, a variety of gases used in
canned-air products are highly flammable. Follow these basic steps from Washington
L&I to help keep your employees safe from hazards associated with canned-air products:
- Ensure the products are used in an open and well-ventilated area.
- Check that a non-flammable version is being used.
- Make sure users read the label on the can and follow instructions on using the product
safely. Post the Material Safety Data Sheet (or Safety Data Sheet) so more thorough
hazard information is available to employees.
- Consider whether eye, face or skin protection is needed.
More than 400 Americans die from unintentional carbon monoxide poisoning every year, according to the Centers for Disease Control and Prevention. More than 20,000 visit
the emergency room, and more than 4,000 others are hospitalized.
Where Does Carbon Monoxide Come From?
Carbon monoxide is an odorless, colorless gas that often goes undetected, striking
victims caught off guard or in their sleep.
This "silent killer" is produced by burning fuel in cars or trucks, small engines,
stoves, lanterns, grills, fireplaces, gas ranges, portable generators or furnaces.
When the gas builds up in enclosed spaces, people or animals who breathe it can be
poisoned. Ventilation does not guarantee safety.
The Consumer Product Safety Commission says about 170 people in the United States
die every year from carbon monoxide produced by non-automotive consumer products,
such as room heaters. So as the weather turns colder, it's important to take extra
Who is at Risk?
Exposure to carbon monoxide can result in permanent neurological damage or death,
and anyone can be at risk.
The CDC says infants, the elderly, and people with chronic heart disease, anemia or
breathing problems are more prone to illness or death, but carbon monoxide doesn't
discriminate – especially if certain conditions are present.
In July 2015, for example, four young people and a dog were found dead of carbon monoxide
poisoning inside a cabin in Maine. Authorities believe they went to bed without shutting off a gas-powered generator running in the basement.
How Can I Prevent Carbon Monoxide Poisoning in My Home?
Winter can be a prime time for carbon monoxide poisoning as people turn on their heating
systems and mistakenly warm their cars in garages.
The National Safety Council recommends you install a battery-operated carbon monoxide
detector in your home near the bedrooms. Check or replace the battery when you change
the time on your clocks each spring and fall. The CDC offers these additional tips:
- Have your heating system, water heater and any other gas or coal-burning appliances
serviced by a qualified technician every year
- Do not use portable flameless chemical heaters indoors
- Never use a generator inside your home, basement or garage or less than 20 feet from
any window, door or vent; fatal levels of carbon monoxide can be produced in just
- Have your chimney checked and cleaned every year, and make sure your fireplace damper
is open before lighting a fire and well after the fire is extinguished
- Make sure your gas appliances are vented properly
- Never use a gas oven for heating your home
- Never let a car idle in the garage
- Know the symptoms of carbon monoxide poisoning
Steps to Take When Carbon Monoxide Alarm Sounds
The CPSC says never ignore a carbon monoxide alarm, and do not try to find the source of the gas. Instead, follow these steps:
- Immediately move outside to fresh air
- Call emergency services, fire department or 911
- Do a head count to check that all persons are accounted for
- Do not reenter the premises until emergency responders have given you permission to
Symptoms of Carbon Monoxide Poisoning
The U.S. Fire Administration has put together materials on the dangers of carbon monoxide. Included is a list of carbon monoxide poisoning symptoms.
Low to moderate carbon monoxide poisoning is characterized by:
- Shortness of breath
High level carbon monoxide poisoning results in:
- Mental confusion
- Loss of muscular coordination
- Loss of consciousness
Symptom severity varies depending on the level of carbon monoxide and duration of
exposure. Mild symptoms sometimes are mistaken for flu.