Why Emergency Rooms Are So Cold: 15 Real Reasons

If you have ever shivered in a hospital gown and wondered why are emergency rooms so cold, here is the short answer: ERs are kept cool on purpose. Cooler, drier air helps limit the growth of some germs, offsets the heat produced by medical equipment and constantly moving staff, keeps feverish patients more comfortable, and meets strict hospital ventilation and humidity standards. Some reasons are backed by building codes and infection-control guidance; others are practical habits or long-standing hospital tradition. Below are 15 real reasons the ER feels chilly, plus what you can do about it, and when feeling cold is actually a warning sign.

Most U.S. emergency departments hold their thermostats somewhere in the range of roughly 68 to 73°F (20 to 23°C), with tightly controlled humidity. That does not sound extreme on paper, but when you are sitting still, undressed into a thin gown, and possibly unwell, it feels much colder than it would at home. Here is why the ER stays that way.

15 Reasons Emergency Rooms Are So Cold

1. Cool, dry air helps limit microbial growth

Many bacteria and molds multiply faster in warm, humid environments. Keeping air cooler and drier does not “kill germs”. That is a common oversimplification, but it makes the environment less favorable for some microorganisms to grow on surfaces and in moisture-prone areas. This is one piece of a much larger infection-control system that also includes hand hygiene, surface disinfection, and air filtration.

2. Humidity control is part of infection control

Closely tied to temperature is humidity. Hospital standards call for keeping relative humidity within a controlled band, because persistently damp air encourages mold and bacterial growth in ductwork and on surfaces. Air conditioning is how buildings pull moisture out of the air: so a well-dehumidified ER is, almost by definition, a cool one.

3. Medical equipment generates a lot of heat

CT scanners, X-ray machines, ultrasound units, lab analyzers, monitors, and computers all throw off heat continuously. At Bellaire ER, our on-site CT, X-ray, ultrasound, and laboratory run around the clock. Cooling protects that equipment from overheating and keeps rooms from becoming stuffy. The thermostat is set for the machines as much as for the people.

4. Staff are in constant motion

Physicians, nurses and technicians walk miles per shift, lift and reposition patients, perform chest compressions, and hustle between rooms. A temperature that feels cold to a patient lying still feels about right to someone working hard. Since staff must function at their best for 12 hours at a time, the environment is tuned toward the people doing physical work.

5. Staff wear layers of PPE

Gowns, gloves, masks, face shields, and lead aprons for imaging trap body heat. A clinician wearing full protective equipment in a 75°F room would overheat quickly. Cooler ambient air makes PPE tolerable, which in turn makes it more likely to be worn correctly and consistently.

6. Cool air is more comfortable for patients with fever

Fever is one of the most common reasons people come to the ER. A febrile patient in a warm room feels dramatically worse. Cooler air provides passive relief while the underlying cause is treated. The room is, in a sense, biased toward the sickest people in it.

7. Cooler air can ease nausea

Many patients and clinicians find that warm, stuffy air makes nausea worse and cool air makes it more bearable. This is largely practical experience rather than strong published evidence, but it is one of the everyday reasons staff keep treatment areas cool.

8. Medications and lab samples need temperature control

Many medications, IV fluids, vaccines and laboratory specimens must be stored and handled within specific temperature ranges. While refrigerators handle the strictest requirements, keeping the whole department reliably cool protects room-temperature supplies from heat excursions.

9. High air-exchange rates are required by ventilation standards

Hospital ventilation guidance from the CDC and standards such as ANSI/ASHRAE/ASHE Standard 170 require healthcare spaces to completely exchange their air many times per hour, far more than an office or home. Constantly moving, filtered air dilutes airborne contaminants, but all that airflow also feels like a draft and makes the room feel colder than the thermostat reads.

10. It is a carryover from operating-room practice

Operating rooms have long been kept cold, historically to slow bacterial growth and to keep gowned, gloved surgical teams under hot lights from sweating into the sterile field. Emergency departments perform procedures too, and much of hospital culture and building design inherited the “cold is clean” convention from the OR. Today, evidence actually favors actively warming surgical patients to prevent complications, a good example of how some of these reasons are tradition as much as science.

11. Cool temperatures help staff stay alert

Warm rooms make people drowsy; cooler rooms tend to keep people alert. In a setting where a missed detail can be dangerous, especially on overnight shifts, a slightly cool environment is a simple, low-cost nudge toward vigilance. The supporting research is modest, but the logic is widely accepted in 24/7 workplaces.

12. Cool, well-ventilated air controls odors

Emergency departments deal with bodily fluids, wounds and illness. Odor molecules spread more readily in warm air, and cool, rapidly exchanged air keeps the department smelling neutral. Which matters for everyone’s comfort, including patients already fighting nausea.

13. Building HVAC systems use standardized set points

A hospital’s air handling is engineered as one system serving many spaces with different requirements: imaging suites, labs, trauma rooms, waiting areas. Set points are standardized to satisfy the most demanding spaces and to meet licensing and code requirements. The result: the waiting room is often as cool as the CT suite, even though the people in it might prefer otherwise.

14. Doors open constantly and patient volume varies

Ambulance bays and entrance doors open around the clock, and crowd sizes swing hour to hour. In Houston’s climate, every door opening lets in heat and humidity, and every additional person adds body heat. HVAC systems are set to stay ahead of those swings, which usually means erring on the cool side.

15. It is easier to warm a cold patient than to cool a warm room

This is the practical bottom line. If you are cold, staff can hand you a warmed blanket in seconds. If the department is too warm, there is no quick fix for anyone: feverish patients suffer, equipment runs hot, and gowned staff sweat. So hospitals deliberately choose “slightly too cold plus blankets” over “slightly too warm,” because cold is the only side of the tradeoff that has an instant remedy. A cooler, calmer-feeling environment can also help take the edge off an anxious visit.

Cold in the ER? Here’s What You Can Do

You do not have to tough it out:

Ask for a warmed blanket. Emergency rooms, including Bellaire ER, stock blanket warmers, and staff hand them out all day. Ask as many times as you need one.
Bring layers if you have time before you come in: a sweater, socks or a jacket you can wear over a gown.
Tell your nurse if you cannot get warm. Comfort is part of care, and persistent chills are also useful clinical information (more below).

Feeling chilly in the ER is normal and fixable. Warmth is always available for the asking. You can read more about what to expect during a visit on our emergency services page, and check current ER wait times before you arrive.

When Feeling Cold Is a Warning Sign

Most of the time, being cold in an ER is just the room. But new chills, shivering or cold, clammy skin can signal a medical emergency, including:

Sepsis: the body’s life-threatening response to infection. Fever with shaking chills, confusion, rapid breathing, or a fast heart rate needs emergency evaluation immediately. Learn the warning signs on our sepsis page.
Shock: cold, pale, sweaty skin with dizziness, weakness or a racing pulse means the body’s circulation is failing and is always an emergency.
Hypothermia: a dangerously low body temperature from exposure, certain medications, or severe illness.

If you or someone near you has chills with confusion, trouble breathing, chest pain, or cold clammy skin, do not wait it out at home. When in doubt, see our guide on when to visit the ER, or just come in.

Cold Room, Warm Care: 24/7 at Bellaire ER

Bellaire ER is a 24/7 freestanding emergency room at 5302 Bellaire Blvd, Bellaire, TX 77401, staffed by board-certified emergency physicians with on-site CT, X-ray, ultrasound and lab. Yes, our rooms run cool, and yes, we will hand you a warm blanket the moment you ask.

Call us: (713) 660-0001
Get directions: 5302 Bellaire Blvd, Bellaire, TX 77401
Save your spot online before you arrive.

Sources & Further Reading

Frequently asked questions

Why are emergency rooms and hospitals kept so cold?

Emergency rooms are kept between roughly 68°F and 73°F (20°C to 23°C) with controlled low humidity to meet healthcare ventilation standards (such as ANSI/ASHRAE/ASHE Standard 170), limit moisture-loving bacteria and mold in ductwork, cool heat-generating CT and laboratory equipment, keep gowned clinicians from overheating, and help feverish or nauseated patients feel more comfortable.

Does cold air in the ER actually kill germs?

No. Cool air around 68°F to 73°F does not kill bacteria or viruses on its own. Instead, air conditioning pulls excess humidity out of the air and pairs with high-efficiency HEPA filtration and frequent air exchanges per hour to make surfaces and ducts less hospitable to microbial growth while diluting airborne particles.

Can I ask for a warm blanket in the emergency room?

Yes. Emergency departments, including Bellaire ER, keep dedicated blanket warmers stocked 24/7 because it is far easier to warm an individual chilly patient with a heated blanket than to cool down an overheated department full of imaging machines, staff in protective gear, and feverish patients.

When are chills or feeling cold in the ER a medical warning sign?

While feeling chilly in a thin gown is normal, sudden shaking chills (rigors), teeth chattering, or cold, pale, clammy skin accompanied by fever, confusion, dizziness, shortness of breath, or a racing pulse can signal sepsis, shock, or hypothermia and should be reported to your nurse or physician immediately.

Why Are Emergency Rooms So Cold? 15 Reasons