WASTE ANESTHETIC 


GASES
 

Occupational Hazards 

in Hospitals 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health 

Waste Anesthetic Gases
 

Occupational Hazards in Hospitals
 

DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

Centers for Disease Control and Prevention
 

National Institute for Occupational Safety and Health
 
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DHHS (NIOSH) Publication No. 2007–151 

September 2007 

Safer • Healthier • PeopleTM 

ii 
 

 

Contents 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Who is exposed to waste anesthetic gases? . . . . . . . . 2 

What are the health effects of exposure 

to waste anesthetic gases? . . . . . . . . . . . . . . . . . . . 2 

Where are workers most likely to be 

exposed to waste anesthetic gases? . . . . . . . . . . . . 3 

How can employers reduce worker exposures 

to waste anesthetic gases? . . . . . . . . . . . . . . . . . . . 4 

How can operating-room personnel reduce 

their exposures to waste anesthetic gases?. . . . . . . 6 

More information about waste anesthetic gases . . . . 7 

iii 

 

 

 

 

 

 

 

 

 

 

 

 

Waste Anesthetic Gases


 Introduction 


Waste anesthetic gases are small amounts of volatile 

anesthetic gases that leak from the patient’s anesthetic breathing circuit* into the air of operating rooms 

during delivery of anesthesia. These gases may also be 

exhaled by patients recovering from anesthesia. Waste 

anesthetic gases include both nitrous oxide and halogenated anesthetics such as halothane, enflurane, isoflurane, 

desflurane, sevoflurane, and methoxyflurane (no longer 

used in the United States). The halogenated anesthetics 

are often administered in combination with nitrous oxide. Nitrous oxide and some of the halogenated anesthetics may pose a hazard to hospital workers. 

The purpose of this brochure is to do the following: 

 Increase awareness about the adverse health effects of waste anesthetic gases 

 Describe how workers are exposed to waste anesthetic gases 

 Recommend work practices to reduce these exposures 

 Identify methods to minimize leakage of anesthetic gases into the work environment 

*The anesthetic breathing circuit includes the mask, endotracheal 

tube, anesthetic gas machine, ventilator, pumps, scavenging devices, all connecting tubing, and other elements, depending on 

the type of anesthesia delivery system. 

1
 
Who is exposed to waste anesthetic gases? 

The following hospital workers may be exposed to 

waste anesthetic gases: 

 Anesthesiologists
 

 Dentists
 

 Nurse anesthetists
 

 Operating-room nurses
 

 Operating-room technicians 


 Other operating-room personnel
 

 Recovery-room nurses
 

 Other recovery-room personnel
 

 Surgeons
 

What are the health effects of exposure to 

waste anesthetic gases? 

Effects of exposure to high concentrations 

Exposure to high concentrations of waste anesthetic 

gases—even for a short time—may cause the following 

health effects: 

 Headache
 

 Irritability
 

 Fatigue
 

 Nausea
 

 Drowsiness
 

 Difficulties with judgment and coordination
 

 Liver and kidney disease 


2
 
 

 

 

Effects of exposure to low concentrations 

Although some studies report no adverse health effects from long-term exposure to low concentrations of 

waste anesthetic gases, several studies have linked such 

exposure to miscarriages, genetic damage, and cancer 

among operating-room workers. Studies have also reported miscarriages in the spouses of exposed workers 

and birth defects in their offspring. Therefore, NIOSH 

is concerned about worker exposures to these gases and 

recommends controls to prevent exposures. 

Where are workers most likely to be 

exposed to waste anesthetic gases? 

Workers are most likely to be exposed to waste 

anesthetic gases in 

— operating facilities with no automatic ventilation or scavenging systems, 

— operating facilities where these systems are in 

poor condition, or 

—	 recovery rooms where gases exhaled by recovering patients are not properly vented or scavenged. 

Even when scavenging and venting systems are in place, 

workers may be exposed to these gases under the following conditions: 

 When leaks occur in the anesthetic breathing 

circuit (which may leak gas if the connectors, 

tubing, and valves are not maintained and tightly 

connected) 

 When anesthetic gases escape during hookup and 

disconnection of the system 

3
 
 When anesthetic gas seeps over the lip of the 

patient’s mask or from endotracheal coupling (particularly if the mask is poorly fitted—for example, 

during pediatric anesthesia) 

 During dental operations 

 During induction of anesthesia 

How can employers reduce worker 

exposures to waste anesthetic gases? 

Employers can reduce exposures to waste anesthetic 

gases by taking the following steps: 

 Establish a hazard communication program: 

—	 Develop and implement a safety and health 

plan that includes information about exposure 

hazards and methods to control them. 

—	 Label cylinders containing anesthetic agents. 

—	 Make material safety data sheets (MSDSs) 

available. 

—	 Train workers as required by the Occupational 

Safety and Health Administration (OSHA) 

hazard communication standard [29 CFR† 

1910.1200]. 

 Install a scavenging system with the anesthesia 

delivery system to remove waste anesthetic gases 

from the operating room. Place the exhaust in an 

area where waste gases will not be reintroduced 

into intake air for the facility. 

†

See Code of Federal Regulations under More Information About 

Waste Anesthetic Gases. 

4
 
 

 

 

 

 

 Install a ventilation system that circulates and 

replenishes the air in operating rooms (at least 

15 air changes per hour, with a minimum of 3 air 

changes of fresh air per hour). 

 Install a ventilation system that circulates and replenishes the air in recovery rooms (at least 6 air 

changes per hour, with a minimum of 2 air changes of fresh air per hour) to prevent exposure to 

waste anesthetic gases exhaled by patients. 

 Properly maintain anesthesia machines, breathing 

circuits, and waste-gas scavenging systems to minimize leaks of anesthetic gases into the operating 

rooms. 

 Train all workers in hazard awareness, prevention, 

and control of exposures to waste anesthetic gases. 

 Develop a monitoring program supervised by a 

knowledgeable person in every operating facility. 

Such a program should include 

—	 quantitatively evaluating the effectiveness of a 

waste-gas control system and 

—	 repeatedly measuring concentrations of anesthetic gas in the breathing zones of the most 

heavily exposed workers while they perform 

their usual procedures. 

	Keep good records of all collected air sample results for at least 30 years. 

 Keep medical records of a worker’s exposure for 

30 years after his or her employment has ended 

(see 29 CFR 1910.1020 Access to Employee 

Exposure and Medical Records). 

5
 
 Obtain baseline liver and kidney data for operatingroom personnel and monitor their liver and kidney 

functions periodically. 

 Record medical histories for workers and their 

families, including occupational histories and outcomes of all pregnancies of female workers and 

wives of male workers (if possible). 

How can operating-room personnel reduce 

their exposures to waste anesthetic gases? 

Anesthetic gases cannot be detected by their odor until 

concentrations are very high. For example, halothane 

cannot be detected by 50% of the general population 

until the concentration is more than 125 times the 

NIOSH recommended exposure limit. 

Reduce exposures to waste anesthetic gases by following these procedures before anesthesia begins: 

 Inspect the anesthetic delivery system before each 

use. Look for irregularities or breaks. 

 Check the patient’s breathing circuit for negative 

pressure and positive pressure relief as part of the 

daily machine checklist. 

 Turn on the room or local ventilation system. 

 Make sure the scavenging equipment is properly 

connected. 

 Connect the gas outlet to the hospital’s central 

scavenging system. 

 Start the gas flow after the laryngeal mask or endotracheal tube is installed. 

6
 
 

 Fill vaporizers under a ceiling-mounted hood with 

an active evacuation system. 

 Fill vaporizers before or after the anesthetic procedure. 

 Make sure that uncuffed endotracheal tubes create a completely sealed airway. 

 Use the lowest anesthetic gas flow rates possible 

for the proper functioning of the anesthesia delivery system and for patient safety. 

 Avoid very high anesthetic gas flow rates to prevent leaks: high flow rates generate more waste 

anesthetic gases than low flow rates. 

 Do not deliver anesthesia by open drop (dripping 

liquid, volatile anesthetic onto gauze). 

 If a mask is used, make sure it fits the patient 

well. 

 Eliminate residual gases through the scavenging 

system as much as possible before disconnecting a 

patient from a breathing system. 

 Turn the gas off before turning off the breathing 

system. 

More information about waste 

anesthetic gases 

Bovin JF [1997]. Risk of spontaneous abortion in women occupationally exposed to anesthetic gases: a metaanalysis. Occup Environ Med 54:541–548. 

7
 
CFR. Code of Federal regulations. Washington, DC: 

U.S. Government Printing Office, Office of the Federal 

Register. 

Guirguis SS, Pelmear PL, Roy ML, Wong L [1990]. 

Health effects associated with exposure to anaesthetic 

gases in Ontario hospital personnel. Br J Ind Med 

47:490–497. 

Hoerauf K, Lierz M, Wiesner G, Schroegendorfer K, 

Lierz P, Spacek A, Brunber L, Nusse M [1999]. Genetic 

damage in operating room personnel exposed to isoflurane and nitrous oxide. Occup Environ Med 56:433– 

437. 

NIOSH [1977]. Criteria for a recommended standard: 

occupational exposure to waste anesthetic gases and 

vapors. Cincinnati, OH: U.S. Department of Health, 

Education, and Welfare, Public Health Service, Center 

for Disease Control, National Institute for Occupational 

Safety and Health, DHEW (NIOSH) Publication No. 

77–140. 

NIOSH [2004]. NIOSH respirator selection logic. 

Cincinnati, OH: U.S. Department of Health and 

Human Services, Public Health Service, Centers for 

Disease Control and Prevention, National Institute for 

Occupational Safety and Health, DHHS (NIOSH) 

Publication No. 2005–100. 

NIOSH [1994]. Technical report. Control of nitrous 

oxide in dental operatories. Cincinnati, OH: U.S. 

Department of Health and Human Services, Public 

Health Service, Centers for Disease Control and 

Prevention, National Institute for Occupational Safety 

and Health, DHHS (NIOSH) Publication No. 94–129. 

8
 
OSHA [1991]. Waste anesthetic gases. Washington, 

DC: U.S. Department of Labor, Occupational Safety 

and Health Administration, OSHA Fact Sheet 91–38. 

OSHA[2000]. Anesthetic gases: guidelines for workplace exposures. Washington, DC: U.S. Department of 

Labor, Occupational Safety and Health Administration 

[www.osha.gov/dts/osha/anestheticgases/]. 

9
 
4676 Columbia P

National Institute for Occupational Safety and Health Centers for Disease Control and Prevention DEPARTMENT OF HEALTH AND HUMAN SERVICES 

arkway 

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 (1–800–232–4636) 

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www.cdc.gov/niosh. 

to NIOSH For a monthly update on news at NIOSH, subscribe 

eNews by visiting www.cdc.gov/niosh/eNews. 

Safer • Healthier • PeopleDHHS (NIOSH) Publication No. 2007–151 

TM