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III. Safety Concerns and Emergency
Laboratory Equipment Students need to do science, not just
read about science. As an outcome of inquiry-based learning, students will
recognize that science is more than a body of knowledge. It is also a way of
thinking and a way of investigating. Investigation requires the use of a
laboratory environment. Class size, facility design, safety equipment, and
fire prevention all must be considered when establishing a safe laboratory
environment.
Many accidents in the science
laboratory can be traced to overcrowding. The correlation between increased
class size with increased accident rate has been
documented. With more students moving about carrying reagents and equipment,
the risk of an accident increases while direct supervision by the teacher
becomes more difficult. A teacher who believes that the laboratory is unsafe
due to overcrowding should communicate those concerns in writing to the
department chairperson, principal, and science supervisor. Teachers and
administrators should be aware of national and state recommendations
regarding class size in science and work collaboratively to create a safe
laboratory environment. 1. Recommendations
of Science Organizations a. Major science
education organizations offer the following recommendations: The
National Science Teachers Association (NSTA), National Association of Biology
Teachers (NABT), and National Science Education Leadership Association
(NSELA) are in agreement that the maximum number of students a single teacher
can supervise properly in a science classroom is 24. The Association for
Science Education calls for a maximum class size of 20 for students aged 5-16
and a maximum of 14 students over 16 years of age. These
recommendations are supported by studies reported in Third Sourcebook for
Science Supervisors, NSTA, 1988, stating that science classes should be
at 24 students per class with a maximum of 30. One study cited in that
publication concludes that a safe science class size contains no more than 22
students. In 1990, the National Science Teachers Association adopted a
position statement on laboratory science that stated the number of students
assigned to a science class should not exceed 24. The
following websites offer more information on this topic: b. The Third
Sourcebook for Science Supervisors, NSTA, 1988, also states that the
accident potential for a science class increases when the number of square
feet per student falls below 41. c. Pathways to the Science Standards - High School, NSTA, 1996,
recommends 45 square feet per student for a combination science
laboratory/classroom. Because effective science instruction integrates
seatwork with laboratory experiences, it is important to maintain
approximately 40 to 50 square feet per student in the science classroom. d. The Maryland
Science Supervisors Association position statement Class Size
Recommendations for Safe and Effective Science Education, 1999, expresses
support and agreement with the recommendations of NSTA, NABT and NSELA. 2. State Criteria Many states have
instituted specific criteria for the number of students and/or the allocation
of space per student in a science classroom. a. Space
Allocations. State space allocations per student in science classrooms:
i.
Vermont: state code calls for 50 square
feet/student.
ii.
California: State Administrative Code
requires 54 square feet/student.
iii.
Maryland: The State Department of Education
recommends 45 square feet/student (Science Facility Design Guidelines,
1994). b. Students Per Classroom. Many states have established
recommendations on the maximum number of students in each science classroom:
i.
Five states recommend a maximum of 24 students per science
classroom - Florida, New Hampshire, Oklahoma, Texas, and Wisconsin.
ii.
Two states recommend a maximum of 28 students per science
classroom - Georgia and Maryland.
iii.
One state recommends a maximum of 15 students per laboratory -
Iowa.
iv.
One state recommends a maximum of 20 students per classroom -
Wyoming.
v.
One state recommends no more than two students per laboratory
station - Minnesota (1989 science laboratory safety law). 3. Professional
Safety Organizations a. A 1992 survey of
state laws and guidelines on science class size found the following:
i.
One state had enforceable legislation regarding laboratory
class size - Florida.
ii.
20 states have guidelines that either set a maximum class size
of 25 or fewer or base student limits on the size of the classroom.
iii.
Class size is part of the negotiated contract in several
states. b. Building
Officials and Code Administrators (BOCA) International specifies a maximum
occupancy load of 50 square feet per student in a science laboratory (May 24,
1999, interpretation of Section 1008.1.2 of BOCA National Building Code,
1996). c. The National Fire
Prevention Association (NFPA) also specifies a maximum occupancy load of 50
square feet per student in a science laboratory (Section 10-1.7.1 of NAPA
Life Safety Code, 1997). The
following website offers more information on this topic: These
regulations and recommendations from professional organizations identify
clear limits on space allocation and the numbers of students per classroom.
Adherence to the above guidelines allows for a safe learning environment for
students and teachers in science laboratories while facilitating effective,
“hands-on” science activities. 1. Emergency
Evacuation Route Emergency
evacuation routes should be established for each classroom, and students
instructed in evacuation plans. The plans should be a part of the chemical hygiene
plan. 2. Master Gas and
Electric Cut-offs a. Master gas and
electric cut-offs should be readily accessible, preferably outside the
classroom. b. In the event of a
fire or electrical accident, shut off the gas and electricity in the
laboratory. 3. Emergency
Communication Classroom
teachers should be able to use a telephone or intercom to contact
administrators or the school nurse in the event of an emergency. 4. Signs and Labels The
following types of signs and labels should be posted in prominent areas of
the laboratory and adjoining rooms: a. Emergency
telephone numbers b. Laboratory safety
rules c. In chemical
storerooms, the National Fire Protection Association (NFPA) diamond with the
highest hazard ratings of the materials in the rooms •See
Appendix E, NFPA Identification Codes. d. Labels indicating
types of hazardous contents of cabinets e. No Food labels on
refrigerators f. Clearly label
foodstuffs intended for laboratory exercises: Not For
Human Consumption. g. Location signs
for: ·
Fire extinguishers ·
Fire blankets ·
Eyewash station ·
Safety shower ·
Spill kits ·
Goggle cabinet ·
Exits ·
Waste containers (e.g., chemical, broken glass) ·
Master gas and electric cutoff 1. Teaching Students
with Disabilities Science laboratories,
like other school facilities, should be accessible and safe for students with
disabilities. The American Chemical Society manual, “Teaching Chemistry to
Students with Disabilities,” is a good guide to ensuring that students with
disabilities receive the appropriate laboratory experience. The
following website offers more information on this topic: C. Fire Safety and Fire Control In the event of a fire you must
decide if you can fight the fire or need to evacuate the building and call
the fire department. The decision whether or not to fight a fire will depend
on many things, including the size and location of the fire, your confidence
in dealing with the situation, and your training in fire
fighting. Remember that the personal safety of the building’s
occupants must always be the first priority. 1. Extinguishing
Fires a. Small Fires
i.
If a person’s clothing or hair catches on fire, have the person
stop, drop, and roll on the floor to suffocate the flame. Do not use fire
extinguishers on people.
ii.
In the case of a small fire that can be easily extinguished,
the teacher must take prompt action to either treat as a “serious” fire and
evacuate the classroom or extinguish the fire using classroom fire management
equipment.
iii.
A fire in a small vessel can usually be extinguished by
covering the vessel with a nonflammable material such as a fire blanket.
Remove nearby flammable liquids to avoid the spread of the fire. b. Serious Fires
i.
Evacuate everyone from the room.
ii.
Sound the fire alarm and notify the school administration.
iii.
Shut off master gas and electrical power, if possible.
iv.
Close windows and doors, if possible.
v.
Fire fighters should be informed of the potential added
hazards of reagents or other materials present in the classroom or
laboratory. A current inventory of hazardous materials should be available
outside the work area. Posting the National Fire Protection Association
(NFPA) diamond, providing emergency information about the room’s contents, is
the best way to give fire fighters the information they need as they enter
the area. The following
website offers more information on this topic: c. Exceptions In
certain circumstances where a fire may be extinguished through quick and skillful
action, a teacher or other school staff trained in the use of a fire
extinguisher may attempt to put out a fire before it spreads to a larger
area. Such action must be taken from a position that allows for quick escape.
It is important to understand that even small fires cannot always be
extinguished easily. 2. Fire
Extinguishers and Their Use
3. An easy way to remember which class of
extinguisher to use is to think of Class A - ash (solid), B - boil (liquid),
and C - charge (electrical). 4. Fire Blankets a. Fire blankets of flame-retardant
wool are useful for smothering small fires as well as keeping accident
victims warm. They may be rolled or folded and kept in wall-mounted cases. b. For clothing
fires, fire blankets should be used with caution. The best method is the
“stop, drop and roll” method. 1. Eyewash Fountains Eyewash
fountains are essential in areas where reagent chemicals are used. Caustic
chemicals can damage the eye within seconds of contact. The eyewash fountain
should - ·
treat both eyes simultaneously.
·
provide a gentle flow of
water for at least 15 minutes at 0.40 gallon per minute minimum (ANSI Z,
358.1-1998). The
following website offers more information on this topic: ·
be accessible
within 10 seconds from the time of injury. ·
leave both hands free
to hold eyelids open. ·
be accessible for
all students. The National Safety Council recommends that all plumbed eyewashes
be flushed for three minutes a week to reduce the risk of eye infections. A
maintenance record should be maintained. The
following website offers more information on this topic: Portable
eyewash squeeze bottles are not an acceptable alternative because they can
treat only one eye, provide an inadequate water supply, are susceptible to
contamination, and provide a good environment for growth of microorganisms. 1. First Aid a. Every school
should have a safety and first aid plan. b. Each laboratory
should have a first aid station for providing basic first aid and stabilizing
students who will be transported to a medical facility. The stations should
have the following: ·
A standard first aid kit stocked according to school policy
and recommendations of the school nurse ·
Emergency phone numbers posted in a conspicuous place: numbers
for an on-call physician; emergency, fire and police services; poison control;
and medical facilities 1. Safety Shields Portable
safety shields should be used for protection against hazards of limited
severity, such as small splashes, heat, and fires. Use these shields with the
knowledge that they provide no protection at the back and sides. If possible,
the shield should be attached to the surface on which it is placed (perhaps
by clamps). 2. Safety Showers A safety
shower should be available in every laboratory. The shower is used to wash
hazardous chemicals from the skin. The Emergency Eyewash and Shower Equipment
Standard (ANSI. Z, 358.1-1998) requires that an emergency shower be located
no more than 10 seconds in time nor greater than 100 feet in distance from
the site of the emergency, and provide a minimum flow of 30 gallons per
minute. Deluge showers are intended for major spills and should provide an
uninterrupted flow of water until the valve is turned off. The shower should
be tested and the tests recorded periodically in accordance with the school
safety plan or as directed by the manufacturer. A
hand-held sprayer with a six-foot hose is a good alternative for small spills
that frequently occur in the teaching laboratory. Such a sprayer should be a
supplement and not a replacement for a plumbed safety shower. The
following website offers more information on this topic: 3. Sanitation of
Safety Goggles If
safety goggles are used by multiple classes, sanitize them between each
class. Commercially available Ultraviolet (U-V) cabinets include those that
hold up to 30 goggles and take 5-15 minutes per cycle. A
lower-cost option is to use a chemical disinfectant specifically made for
disinfecting goggles. Household bleach and disinfectants can be used by
diluting according to directions on the label. 4. Spill Kits A spill
kit should be accessible in each science classroom or laboratory. The kit
might include: ·
Spill control pillows (which are commercially available) ·
Inert absorbents such as vermiculite, clay, sand, or kitty
litter ·
Neutralizing agents for acid spills such as sodium carbonate
and sodium hydrogen carbonate ·
Neutralizing agents for alkali spills such as sodium hydrogen
sulfate and citric acid ·
Large plastic scoops and other equipment such as brooms,
pails, bags, and dust pans ·
Appropriate personal protective equipment 1. Room ventilation Adequate
ventilation is important in any room in which reagent chemicals are used or
stored. According to Prudent Practices for the Laboratory, the air in
a science laboratory should be changed a minimum of six times per hour. The
following website offers more information on this topic: Chemical
storerooms should have ventilation adequate to keep atmospheric levels of
chemicals below their hazardous limits. As with room ventilation, a minimum of
six air changes per hour are recommended. 2. Fume Hoods Fume
hoods are the most important equipment used to protect teachers and students
from exposure to hazardous chemicals and agents used in the laboratory. a.
Velocity. A face velocity of 80 fpm (the
average velocity of air drawn through the face of the hood) should
effectively remove fumes produced within the hood, conditional on proper
placement and use. b. Rules for Using
Fume Hoods
i.
Do not store reagent chemicals in a fume hood.
ii.
Fume hoods must be inspected for proper use. Devices are
available to measure face velocity.
iii.
Keep the sash at its most efficient level.
iv.
Work as far inside the hood as possible, but keep your head
outside the hood. A minimum working distance of 6 inches from the front of
the hood is recommended.
v.
If possible, the hood should be located away from windows,
doors, and areas of heavy traffic to avoid drafts. |
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