Environmental Engineering Reference
In-Depth Information
•.
Formaldehyde.(1910.1048)
•.
Methylenedianiline.(1910.1050)
•.
1,3-Butadiene.(1910.1051)
•.
Methylene.chloride.(1910.1052)
Recently,.OSHA.has.reduced.the.PEL.for.methylene.chloride.from.400.ppm.to.
25.ppm..This.is.a.huge.reduction.in.the.PEL,.equal.to.a.ifteen-times.reduction.that.
a.worker.can.face.as.a.potential.exposure..This.reduction.indicates.the.potential.of.
methylene.chloride.to.cause.cancer.in.workers.and.should.raise.the.lag.that.chemi-
cals. that. are. believed. to. cause. cancer. are. not. to. be. taken. lightly.. Information. and.
research. are. continuously. evolving. and. providing. new. insight. into. the. dangers. of.
these.chemicals.and.agents.
cold stress
Temperature. is. measured. in. degrees. Fahrenheit. (°F). or. Celsius. (°C).. Most. people.
feel.comfortable.when.the.air.temperature.ranges.from.66°F.to.79°F.and.the.relative.
humidity.is.about.45.percent..Under.these.circumstances,.heat.production.inside.the.
body.equals.the.heat.loss.from.the.body,.and.the.internal.body.temperature.is.kept.
around.98.6°F..For.constant.body.temperature,.even.under.changing.environmental.
conditions,.rates.of.heat.gain.and.heat.loss.should.balance..Every.living.organism.
produces.heat..In.cold.weather.the.only.source.of.heat.gain.is.the.body's.own.internal.
heat.production,.which.increases.with.physical.activity..Hot.drinks.and.food.are.also.
a.source.of.heat.
The. body. loses. heat. to. its. surroundings. in. several. different. ways.. Heat. loss. is.
greatest.if.the.body.is.in.direct.contact.with.cold.water..The.body.can.lose.twenty-ive.
to.thirty.times.more.heat.when.in.contact.with.cold,.wet.objects.than.under.dry.con-
ditions. or. with. dry. clothing.. The. higher. the. temperature. differences. between. the.
body.surface.and.cold.objects,.the.faster.the.heat.loss..Heat.is.also.lost.from.the.skin.
by.contact.with.cold.air..The.rate.of.loss.depends.on.the.air.speed.and.the.tempera-
ture.difference.between.the.skin.and.the.surrounding.air..At.a.given.air.temperature,.
heat. loss. increases. with. air. speed.. Sweat. production. and. its. evaporation. from. the.
skin.also.cause.heat.loss..This.is.important.when.performing.hard.work.
Small.amounts.of.heat.are.lost.when.cold.food.and.drink.are.consumed..As.well,.
heat.is.lost.during.breathing.by.inhaling.cold.air,.and.through.evaporation.of.water.
from.the.lungs.
The. body. maintains. heat. balance. by. reducing. the. amount. of. blood. circulat-
ing. through. the. skin. and. outer. body. parts.. This. minimizes. cooling. of. the. blood.
by.shrinking.the.diameter.of.blood.vessels..At.extremely.low.temperatures,.loss.of.
blood. low. to. the. extremities. may. cause. an. excessive. drop. in. tissue. temperature,.
resulting. in. damage. such. as. frostbite.. Shivering,. which. increases. the. body's. heat.
production,. provides. a. temporary. tolerance. for. cold. but. cannot. be. maintained. for.
long.periods.of.time.
Overexposure.to.cold.causes.discomfort.and.a.variety.of.health.problems..Cold.
stress. impairs. performance. of. both. manual. and. complex. mental. tasks.. Sensitivity.
and. dexterity. of. ingers. lessen. in. cold.. At. lower. temperatures. still,. cold. affects.
