Environmental Engineering Reference
In-Depth Information
.collapse. is. rapid. and. unpredictable.. To. prevent. heat. collapse,. the. worker.
should.gradually.become.acclimatized.to.the.hot.environment.
.
5..
Heat rashes
. are. the. most. common. problem. in. hot. work. environments..
Prickly.heat.manifests.as.red.papules.and.usually.appears.in.areas.where.
the.clothing.is.restrictive..As.sweating.increases,.these.papules.give.rise.to.
a.prickling.sensation..Prickly.heat.occurs.on.skin.that.is.persistently.wetted.
by.unevaporated.sweat;.and.heat.rash.papules.may.become.infected.if.they.
are.not.treated..In.most.cases,.heat.rashes.will.disappear.when.the.affected.
individual.returns.to.a.cool.environment.
.
6.. A.factor.that.predisposes.an.individual.to.
heat fatigue
.is.lack.of.acclimati-
zation..The.use.of.a.program.of.acclimatization.and.training.for.work.in.hot.
environments.is.advisable..The.signs.and.symptoms.of.heat.fatigue.include.
impaired. performance. of. skilled. sensorimotor,. mental,. or. vigilance. jobs..
There.is.no.treatment.for.heat.fatigue.except.to.remove.the.heat.stress.before.
a.more.serious.heat-related.condition.develops.
Workload.assessments.should.be.made.under.conditions.of.high.temperature.and.
heavy.workload..The.workload.category.is.determined.by.averaging.metabolic.rates.
in.kilocalories.used.per.hour.(kcal/hr).for.the.tasks.and.then.ranking.them:
•.
Light.work:.up.to.200.kcal/hr
•.
Medium.work:.200-350.kcal/hr
•.
Heavy.work:.350-500.kcal/hr
Some.examples.of.activities.and.the.workload.involved.are.as.follows:
•.
Light.handwork:.writing,.hand.knitting
•.
Heavy.handwork:.typewriting
•.
Heavy.work.with.one.arm:.hammering.in.nails.(shoemaker,.upholsterer)
•.
Light.work.with.two.arms:.iling.metal,.planing.wood,.and.raking.a.garden
•.
Moderate.work.with.the.body:.cleaning.a.loor,.beating.a.carpet
•.
Heavy.work.with.the.body:.railroad.track.laying,.digging,.debarking.trees
The.most.commonly.used.temperature.index.is.the.Wet.Bulb.Globe.Temperature.
(WBGT).. The. WBGT. reading. should. be. for. continuous. all-day. or. several. hours.
of. exposures. and. then. should. be. averaged. over. a. 60-minute. period.. Intermittent.
exposures.should.be.averaged.over.a.120-minute.period..These.averages.should.be.
.calculated.using.the.following.formulae:
.
1.. For.indoor.and.outdoor.conditions.with.no.solar.load,.WBGT.is.calculated.as
WBGT=0.7NWB+0.3GT
.
2.. For.outdoors.with.a.solar.load,.WBGT.is.calculated.as
WBGT=0.7NWB+0.2GT+0.1DB
