heat stress
Hydration
Drinking enough fluids is one of the most important things you can
do to prevent heat illness. Water is generally sufficient for hydration.
Hydrate Before Work
• Being hydrated when you start work makes it easier to stay hydrated through
the day.
• If you are dehydrated when you start work, you may not be able to drink
enough to catch up with your body’s need for water.
Hydrate During Work
• Drink before feeling thirsty. By the time you feel thirsty, you are already
behind in uid replacement. Dehydration is a primary contributor to
heat exhaustion.
• Your work performance may suer when you
are dehydrated, even if you don’t notice.
• When working in the heat, drink 1 cup
(8 ounces) of water every 15–20 minutes.
• This translates to ¾–1 quart (24–32 ounces)
per hour.
• Drinking at shorter intervals is more eective
than drinking large amounts infrequently.
• Do not drink more than 48 oz (1½ quarts) per hour! Drinking too much
water or other uids (sports drinks, energy drinks, etc.) can cause a medical
emergency because the concentration of salt in the blood becomes too low.
How much water is that?
1
quart
=
1/4 gallon
(32 oz)
=
approx
1
L
Hydrate After Work
• Most people need several hours to drink enough uids to replace what they
have lost through sweat. The sooner you get started, the less strain you place
on your body from dehydration.
• Hydrating after work is even more important if you work in the heat on a
regular basis. Chronic dehydration increases the risk for a number of medical
conditions, such as kidney stones.
Urine
Color
Test
WELL
HYDRATED
HYDRATED DEHYDRATED
Drink water!
SEVERELY DEHYDRATED
Drink water immediately!
Photo by ©Thinkstock
heat stress Hydration
What to Drink
Water
Water will almost
always maintain
hydration during
work in the heat,
as long as you eat
regular meals to
replace salt lost
in sweat.
What to Avoid
Energy Drinks
• Some energy drinks contain much
more caeine than standard servings
of coee, tea, or soft drinks.
• Drinking several energy drinks per
day can raise your caeine levels
enough to aect your heart. High
caeine levels can be risky when
added to the strain placed on your
body by heat.
• Many energy drinks contain as much
or more sugar as soft drinks, which
adds hundreds of extra calories to
your diet.
Alcohol
• Alcohol can cause dehydration.
• Drinking alcohol within 24 hours of
working in the heat can increase the
risk of heat illness.
What about salt tablets?
NIOSH does not recommend taking salt tablets.
In most cases, salt can be replaced by eating
normal meals and snacks throughout the day.
Do not skip meals.
What about caeine?
The amount of caeine in tea, coee, and soft
drinks probably will not have an eect on
overall hydration.
Do I need sports drinks?
In general, eating regular meals with adequate
water intake is sucient to maintain water and
electrolyte balance.
For prolonged sweating lasting several hours,
sports drinks with balanced electrolytes are
another option to replace salt lost in sweat.
Heavy consumption of sports drinks will add
unnecessary calories to your diet due to the
added sugar.
DEPARTMENT OF HEALTH AND HUMAN SERVICES
Centers for Disease Control and Prevention
National Institute for Occupational Safety and Health
DHHS (NIOSH) Publication No. 2017-126
Photo by ©Thinkstock
