Toilet plume

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A toilet plume is the dispersal of microscopic particles as a result of flushing a toilet. Normal use of a toilet by healthy individuals is considered unlikely to be a major health risk. However this dynamic changes if an individual is fighting an illness and currently shedding out a virulent pathogen in their urine, feces or vomitus. There is indirect evidence that specific pathogens such as norovirus or SARS coronavirus could potentially be spread by toilet aerosols, but as of 2015, no direct experimental studies had clearly demonstrated or refuted actual disease transmission from toilet aerosols. It has been hypothesized that dispersal of pathogens may be reduced by closing the toilet lid before flushing, and by using toilets with lower flush energy.

Contents

Possible effects on disease transmission

A video discussing research on the health hazards of aerosol toilet plumes

There is indirect evidence that toilet aerosol can be a vector for diseases that involve acute gastroenteritis with the shedding of large numbers of pathogens through feces and vomit, with normal use of a toilet unlikely to be a major health risk. [1] For example, some epidemiological studies indicate transmission of norovirus in passenger airplanes [2] and ships, [3] and SARS coronavirus through a contaminated building sewage system, [4] via contaminated toilets rather than other routes. [5] The feces and vomit of infected people can contain high concentrations of pathogens, many of which are known to survive on surfaces for weeks or months, and toilets may continue to produce contaminated toilet plumes over multiple successive flushes. Some other pathogens speculatively identified as being of potential concern for these reasons include gram-positive MRSA, Mycobacterium tuberculosis , and the pandemic H1N1/09 virus commonly known as "swine flu". [5]

There is no direct experimental evidence on disease transmission by toilet aerosols. Whether or not aerosols can contain norovirus, SARS coronavirus, or other pathogens has not been directly measured as of 2015. [5] [6] The combination of cleaning and disinfecting surfaces is usually effective at removing contamination, although some pathogens such as norovirus [7] have an apparent resistance to these techniques. [5]

Mechanism

Aerosol droplets produced by flushing the toilet can mix with the air of the room, [6] larger droplets will settle on a surface before they can dry, [5] [8] and can contaminate surfaces such as the toilet seat and handle, which can then be contacted by hands. [1] Smaller aerosol particles can become droplet nuclei as a result of evaporation of the water in the droplet; these have negligible settling velocity and are carried by natural air currents. [8] Disease transmission through droplet nuclei is not a concern for many pathogens, because they are not excreted in feces or vomit, or are susceptible to drying. [5] The critical size dividing these dispersal modes depends on the evaporation rate and vertical distance between the toilet and the surface in question. [8]

Experiments to test bioaerosol production usually involve seeding a toilet with bacteria or virus particles, [5] or fluorescent microparticles, [8] and then testing for their presence on nearby surfaces and in the air, after varying amounts of time. [5] [8] The amount of bioaerosol varies with the type of flush toilet. Older wash-down toilet designs produce more bioaerosol than modern siphoning toilets. [5] Among modern toilets, bioaerosol production increases as qualitative flush energy increases, from low-flush gravity-flow toilets common in residences, to pressure-assisted toilets, to vigorous flushometer toilets often found in public restrooms. [8]

One study found that lowering the toilet lid prevented dispersion of large droplets, and reduced the airborne bacteria concentrations by a factor of 12. The study recommended discouraging the use of lidless toilets, and thus contradicts the US Uniform Plumbing Code specifications for public toilets. [5] [9]

History

Experiments on the bioaerosol content of toilet plumes were first performed in the 1950s. [5] A 1975 study by Charles P. Gerba popularized the concept of disease transmission through toilet plumes. [10] The term "toilet plume" was in use before 1999. [11]

Related Research Articles

<span class="mw-page-title-main">Hygiene</span> Practices performed to preserve health

Hygiene is a set of practices performed to preserve health. According to the World Health Organization (WHO), "Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases." Personal hygiene refers to maintaining the body's cleanliness. Hygiene activities can be grouped into the following: home and everyday hygiene, personal hygiene, medical hygiene, sleep hygiene, and food hygiene. Home and every day hygiene includes hand washing, respiratory hygiene, food hygiene at home, hygiene in the kitchen, hygiene in the bathroom, laundry hygiene, and medical hygiene at home.

<span class="mw-page-title-main">Norovirus</span> Type of viruses that cause gastroenteritis

Norovirus, also known as Norwalk virus and sometimes referred to as the winter vomiting disease, is the most common cause of gastroenteritis. Infection is characterized by non-bloody diarrhea, vomiting, and stomach pain. Fever or headaches may also occur. Symptoms usually develop 12 to 48 hours after being exposed, and recovery typically occurs within one to three days. Complications are uncommon, but may include dehydration, especially in the young, the old, and those with other health problems.

<span class="mw-page-title-main">Flush toilet</span> Toilet that uses water to convey human waste down a pipe

A flush toilet is a toilet that disposes of human waste by using the force of water to flush it through a drainpipe to another location for treatment, either nearby or at a communal facility, thus maintaining a separation between humans and their waste. Flush toilets can be designed for sitting or squatting, in the case of squat toilets. Most modern sewage treatment systems are also designed to process specially designed toilet paper. The opposite of a flush toilet is a dry toilet, which uses no water for flushing.

<span class="mw-page-title-main">Fecal–oral route</span> Disease transmission via pathogens from fecal particles

The fecal–oral route describes a particular route of transmission of a disease wherein pathogens in fecal particles pass from one person to the mouth of another person. Main causes of fecal–oral disease transmission include lack of adequate sanitation, and poor hygiene practices. If soil or water bodies are polluted with fecal material, humans can be infected with waterborne diseases or soil-transmitted diseases. Fecal contamination of food is another form of fecal-oral transmission. Washing hands properly after changing a baby's diaper or after performing anal hygiene can prevent foodborne illness from spreading.

In medicine, public health, and biology, transmission is the passing of a pathogen causing communicable disease from an infected host individual or group to a particular individual or group, regardless of whether the other individual was previously infected. The term strictly refers to the transmission of microorganisms directly from one individual to another by one or more of the following means:

<span class="mw-page-title-main">Natural reservoir</span> Type of population in infectious disease ecology

In infectious disease ecology and epidemiology, a natural reservoir, also known as a disease reservoir or a reservoir of infection, is the population of organisms or the specific environment in which an infectious pathogen naturally lives and reproduces, or upon which the pathogen primarily depends for its survival. A reservoir is usually a living host of a certain species, such as an animal or a plant, inside of which a pathogen survives, often without causing disease for the reservoir itself. By some definitions a reservoir may also be an environment external to an organism, such as a volume of contaminated air or water.

<span class="mw-page-title-main">Sapovirus</span> Genus of viruses

Sapovirus is a genetically diverse genus of single-stranded positive-sense RNA, non-enveloped viruses within the family Caliciviridae. Together with norovirus, sapoviruses are the most common cause of acute gastroenteritis in humans and animals. It is a monotypic taxon containing only one species, the Sapporo virus.

Aerosolization is the process or act of converting some physical substance into the form of particles small and light enough to be carried on the air i.e. into an aerosol. Aerosolization refers to a process of intentionally oxidatively converting and suspending particles or a composition in a moving stream of air for the purpose of delivering the oxidized particles or composition to a particular location.

<span class="mw-page-title-main">Bioaerosol</span> Airborne particles containing living organisms

Bioaerosols are a subcategory of particles released from terrestrial and marine ecosystems into the atmosphere. They consist of both living and non-living components, such as fungi, pollen, bacteria and viruses. Common sources of bioaerosols include soil, water, and sewage.

<span class="mw-page-title-main">Airborne transmission</span> Disease transmission by airborne particles

Airborne transmission or aerosol transmission is transmission of an infectious disease through small particles suspended in the air. Infectious diseases capable of airborne transmission include many of considerable importance both in human and veterinary medicine. The relevant infectious agent may be viruses, bacteria, or fungi, and they may be spread through breathing, talking, coughing, sneezing, raising of dust, spraying of liquids, flushing toilets, or any activities which generate aerosol particles or droplets.

A fomite or fomes is any inanimate object that, when contaminated with or exposed to infectious agents, can transfer disease to a new host.

<span class="mw-page-title-main">Wells curve</span> Science of medicine

The Wells curve is a diagram, developed by W. F. Wells in 1934, which describes what is expected to happen to small droplets once they have been exhaled into air. Coughing, sneezing, and other violent exhalations produce high numbers of respiratory droplets derived from saliva and/or respiratory mucus, with sizes ranging from about 1 µm to 2 mm. Wells' insight was that such droplets would have two distinct fates, depending on their sizes. The interplay of gravity and evaporation means that droplets larger than a humidity-determined threshold size would fall to the ground due to gravity, while droplets smaller than this size would quickly evaporate, leaving a dry residue that drifts in the air. Since droplets from an infected person may contain infectious bacteria or viruses, these processes influence transmission of respiratory diseases.

<span class="mw-page-title-main">Respiratory droplet</span> Type of particle formed by breathing

A respiratory droplet is a small aqueous droplet produced by exhalation, consisting of saliva or mucus and other matter derived from respiratory tract surfaces. Respiratory droplets are produced naturally as a result of breathing, speaking, sneezing, coughing, or vomiting, so they are always present in our breath, but speaking and coughing increase their number.

<span class="mw-page-title-main">Feline zoonosis</span> Medical condition

A feline zoonosis is a viral, bacterial, fungal, protozoan, nematode or arthropod infection that can be transmitted to humans from the domesticated cat, Felis catus. Some of these diseases are reemerging and newly emerging infections or infestations caused by zoonotic pathogens transmitted by cats. In some instances, the cat can display symptoms of infection and sometimes the cat remains asymptomatic. There can be serious illnesses and clinical manifestations in people who become infected. This is dependent on the immune status and age of the person. Those who live in close association with cats are more prone to these infections, but those that do not keep cats as pets can also acquire these infections as the transmission can be from cat feces and the parasites that leave their bodies.

<span class="mw-page-title-main">Dental aerosol</span> Hazardous biological compound

A dental aerosol is an aerosol that is produced from dental instrument, dental handpieces, three-way syringes, and other high-speed instruments. These aerosols may remain suspended in the clinical environment. Dental aerosols can pose risks to the clinician, staff, and other patients. The heavier particles contained within the aerosols are likely to remain suspended in the air for relatively short period and settle quickly onto surfaces, however, the lighter particles may remain suspended for longer periods and may travel some distance from the source. These smaller particles are capable of becoming deposited in the lungs when inhaled and provide a route of diseases transmission. Different dental instruments produce varying quantities of aerosol, and therefore are likely to pose differing risks of dispersing microbes from the mouth. Air turbine dental handpieces generally produce more aerosol, with electric micromotor handpieces producing less, although this depends on the configuration of water coolant used by the handpiece.

An aerosol-generating procedure (AGP) is a medical or health-care procedure that a public health agency such as the World Health Organization or the United States Centers for Disease Control and Prevention (CDC) has designated as creating an increased risk of transmission of an aerosol borne contagious disease, such as COVID-19. The presumption is that the risk of transmission of the contagious disease from a patient having an AGP performed on them is higher than for a patient who is not having an AGP performed upon them. This then informs decisions on infection control, such as what personal protective equipment (PPE) is required by a healthcare worker performing the medical procedure, or what PPE healthcare workers are allowed to use.

Human-to-human transmission (HHT) is an epidemiologic vector, especially in case the disease is borne by individuals known as superspreaders. In these cases, the basic reproduction number of the virus, which is the average number of additional people that a single case will infect without any preventative measures, can be as high as 203.9. Interhuman transmission is a synonym for HHT.

<span class="mw-page-title-main">Source control (respiratory disease)</span> Strategy for reducing disease transmission

Source control is a strategy for reducing disease transmission by blocking respiratory secretions produced through speaking, coughing, sneezing or singing. Surgical masks are commonly used for this purpose, with cloth face masks recommended for use by the public only in epidemic situations when there are shortages of surgical masks. In addition, respiratory etiquette such as covering the mouth and nose with a tissue when coughing can be considered source control. In diseases transmitted by droplets or aerosols, understanding air flow, particle and aerosol transport may lead to rational infrastructural source control measures that minimize exposure of susceptible persons.

<span class="mw-page-title-main">Transmission of COVID-19</span> Mechanisms that spread coronavirus disease 2019

The transmission of COVID-19 is the passing of coronavirus disease 2019 from person to person. COVID-19 is mainly transmitted when people breathe in air contaminated by droplets/aerosols and small airborne particles containing the virus. Infected people exhale those particles as they breathe, talk, cough, sneeze, or sing. Transmission is more likely the closer people are. However, infection can occur over longer distances, particularly indoors.

John J. Lowe is an American infectious disease scientist, assistant vice chancellor for health security at University of Nebraska Medical Center, and associate professor in the Department of Environmental, Agricultural and Occupational Health at University of Nebraska Medical Center College of Public Health. In 2014, he led Nebraska Medicine hospital’s effort to treat and care for Ebola virus disease patients and led the University of Nebraska Medical Center’s coronavirus disease 2019 response efforts.

References

  1. 1 2 Barker, J.; Jones, M. V. (2005). "The potential spread of infection caused by aerosol contamination of surfaces after flushing a domestic toilet". Journal of Applied Microbiology. 99 (2): 339–347. doi:10.1111/j.1365-2672.2005.02610.x. ISSN   1364-5072. PMID   16033465. S2CID   25625899.
  2. ↑ Widdowson, Marc-Alain; Glass, Roger; Monroe, Steve; Beard, R. Suzanne; Bateman, John W.; Lurie, Perrianne; Johnson, Caroline (20 April 2005). "Probable transmission of norovirus on an airplane". JAMA. 293 (15): 1859–1860. doi:10.1001/jama.293.15.1859. ISSN   1538-3598. PMID   15840859.
  3. ↑ Ho, Mei-Shang; Monroe, Stephan S.; Stine, Sarah; Cubitt, David; Glass, Roger I.; Madore, H. Paul; Pinsky, Paul F.; Ashley, Charles; Caul, E.O. (21 October 1989). "Viral Gastroenteritis Aboard a Cruise Ship". The Lancet. 334 (8669): 961–965. doi:10.1016/s0140-6736(89)90964-1. ISSN   0140-6736. PMID   2571872. S2CID   29429652.
  4. ↑ "Outbreak of Severe Acute Respiratory Syndrome (SARS) at Amoy Gardens, Kowloon Bay, Hong Kong: Main Findings of the Investigation" (PDF). Hong Kong Special Administrative Region Department of Health. 29 March 2011. Archived (PDF) from the original on 20 April 2017.
  5. 1 2 3 4 5 6 7 8 9 10 11 Johnson, David L.; Mead, Kenneth R.; Lynch, Robert A.; Hirst, Deborah V.L. (March 2013). "Lifting the lid on toilet plume aerosol: A literature review with suggestions for future research". American Journal of Infection Control. 41 (3): 254–258. doi:10.1016/j.ajic.2012.04.330. PMC   4692156 . PMID   23040490.
  6. 1 2 Jones, RM; Brosseau, L. M. (May 2015). "Aerosol transmission of infectious disease". Journal of Occupational and Environmental Medicine. 57 (5): 501–8. doi:10.1097/JOM.0000000000000448. PMID   25816216. S2CID   11166016.
  7. ↑ Barker, J.; Vipond, I. B.; Bloomfield, S. F. (1 September 2004). "Effects of cleaning and disinfection in reducing the spread of Norovirus contamination via environmental surfaces". The Journal of Hospital Infection. 58 (1): 42–49. doi:10.1016/j.jhin.2004.04.021. ISSN   0195-6701. PMID   15350713.
  8. 1 2 3 4 5 6 Johnson, David; Lynch, Robert; Marshall, Charles; Mead, Kenneth; Hirst, Deborah (1 September 2013). "Aerosol Generation by Modern Flush Toilets". Aerosol Science and Technology. 47 (9): 1047–1057. Bibcode:2013AerST..47.1047J. doi:10.1080/02786826.2013.814911. ISSN   0278-6826. PMC   4666014 . PMID   26635429. Archived from the original on 15 April 2017.
  9. ↑ Best, E. L.; Sandoe, J. a. T.; Wilcox, M. H. (1 January 2012). "Potential for aerosolization of Clostridium difficile after flushing toilets: the role of toilet lids in reducing environmental contamination risk". The Journal of Hospital Infection. 80 (1): 1–5. doi:10.1016/j.jhin.2011.08.010. ISSN   1532-2939. PMID   22137761.
  10. ↑ Ray, C. Claiborne (26 November 2012). "Does Flushing a Toilet Release Germs Into the Air?". The New York Times . ISSN   0362-4331. Archived from the original on 23 June 2016. Retrieved 15 July 2016.
  11. ↑ Adams, Cecil (15 April 1999). "The Straight Dope". Chicago Reader. Archived from the original on 20 April 2017. Retrieved 20 April 2017.
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