Health and Safety Practices Survey of Healthcare Workers

Nitrous oxide (in dental settings)

Here you will learn what we found regarding adherence to recommended exposure control practices.


Nitrous oxide (with oxygen) is the most common inhaled anesthetic used in dentistry to control patient anxiety and pain. It is used by most (89%) dentists who provide care to pediatric patients and a majority (58%) of all dentists.1-3 In certain states dental hygienists and dental assistants are also licensed to administer nitrous oxide.4,5

More than 650,000 dentists, dental hygienists and dental assistants practice dentistry in the U.S.6 Dental practitioners may be exposed to excessive levels of nitrous oxide when recommended engineering controls (e.g., patient nasal scavenging mask, or local exhaust ventilation (LEV) near the patient’s mouth), administrative controls, and work practice controls are not used or used improperly.

Acute work-related exposure to nitrous oxide may cause7,8  :

  • Lightheadedness
  • Eye and upper airway irritation
  • Cough
  • Shortness of breath
  • Decreases in mental performance and manual dexterity

Chronic work-related exposure to high levels of nitrous oxide may cause:

  • Increased risk of neurologic, renal and liver disease11,12
  • Increased risk of miscarriage and fertility issues among female dental assistants who worked in offices where scavenging equipment was not used 9,10

This study examined how well dental practitioners adhere to recommended best practices for minimizing exposure to nitrous oxide. We also assessed whether exposure varied among dental practitioners treating adults versus children. Because almost all of the dental practitioners were in private practice and only used nitrous oxide, analyses excluded respondents in other types of ownership (i.e., non-profits, public sector) and those who reported using other inhaled anesthetics (e.g., sevoflurane).

Overall, 172 dentists and 112 dental hygienists and dental assistants who administered nitrous oxide in the 7 days prior to the survey were included in the analyses. We found that 96% of respondents who cared for pediatric patients and 91% who cared for adult patients always used nasal scavenging masks. However, adherence to other recommended practices for administering nitrous oxide was lacking (see below), which may increase exposure risk. Successful management of nitrous oxide should include:

  • Nasal scavenging masks
  • Supplementary LEV if needed
  • Adequate general ventilation
  • Regular inspection for leaks of nitrous oxide delivery and scavenging equipment
  • Availability of standard procedures to minimize exposure
  • Periodic training for those administering nitrous oxide
  • Medical surveillance of workers who administer nitrous oxide

Dentists and dental staff share responsibility for adhering to recommended practices to minimize exposure to nitrous oxide and other anesthetic gases used during dental procedures.

Best practices and study findings

What we found What employers/employees should do
51% of respondents with adult patients and 47% of respondents with pediatric patients did not check nitrous oxide equipment for leaks Prior to first use each day and every time a gas cylinder is changed, test connections for leaks using a soap solution.8,13
16% of respondents with adult patients and 14% of respondents with pediatric patients started nitrous oxide gas flow before nasal mask was placed on the patient Start nitrous oxide gas flow AFTER nasal mask is securely placed over the patient’s nose to minimize nitrous oxide exposure.8,13
10% of respondents with adult patients and 8% of respondents with pediatric patients did not turn off nitrous oxide gas flow before turning off oxygen flow to the patient Turn off nitrous oxide gas flow BEFORE turning off oxygen flow to the patient to minimize nitrous oxide exposure.8,13
13% of all respondents said that employer safe handling procedures were unavailable. Make available to employees safe handling procedures for nitrous oxide.8,13
3% of all respondents said that they never received training and, of those who received training, 77% said that it was more than 12 months ago. Provide initial and annual refresher training on the known and potential adverse health effects of nitrous oxide and appropriate methods to minimize exposurede.13


1 Davis MJ. [1988] Conscious sedation practices in pediatric dentistry: a survey of members of the American Board of Pediatric Dentistry College of Diplomates. Pediatr Dent 10(4):328-329. Retrieved from iconexternal icon.

2 Wilson S. [1996] A survey of the American Academy of Pediatric Dentistry membership: nitrous oxide and sedation. Am Acad Pediatr Dent 18(4):287-293. Retrieved from iconexternal icon.

3 Howard WR. [1997] Nitrous oxide in the dental environment: assessing the risk, reducing the exposure. J Am Dent Assoc 128(3):356-360.

4 American Dental Hygienists‘ Association. [2015] Nitrous oxide administration by dental hygienists – state chart. Revised September 2015. Retrieved from iconexternal icon.

5 American Dental Association. [2011] Expanded functions for dental assistants. March 28, 2011. Retrieved from iconexternal icon.

6 Bureau of Labor Statistics (BLS). Household data annual averages-employed persons by detailed occupation. Retrieved from iconexternal icon.

7 New Jersey Department of Health and Senior Services. [2004] Hazardous substance fact sheet: Nitrous oxide. Retrieved from iconexternal icon.

8 National Institute for Occupational Safety and Health (NIOSH). [1994] Controlling exposures to nitrous oxide during anesthetic administration.

9 Rowland AS, Baird DD, Shore DL, Weinberg, CR, Savitz DA, Wilcox AJ. [1995] Nitrous oxide and spontaneous abortion in female dental assistants. Am J Epidemiol 141:531-38.

10 Rowland AS, Baird DD, Weinberg CR, Shore DL, Shy CM, Wilcox AJ. [1992] Reduced fertility among women employed as dental assistants exposed to high levels of nitrous oxide. N Engl J Med 327:993-997.

11 Cohen EN, Gift HC, Brown BW, et al. [1980] Occupational disease in dentistry and chronic exposure to trace anesthetic gases. J Am Dent Assoc 101:21-31.

12 Brodsky JB, Cohen EN, Brown Jr BW, Wu ML, Whitcher CE. [1981] Exposure to Nitrous Oxide and Neurologic Disease among Dental Professionals. Anesthesia and Analgesia 60(5): 297-301.

13 Occupational Safety and Health Administration (OSHA). [2000] Anesthetic gases: Guidelines for workplace exposuresexternal icon

Survey and report

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Journal articleexternal icon

(The free full text article will be available in Pub Med Centralexternal icon one year after the article has been published)

Page last reviewed: August 14, 2017