What Are Disinfectants and What Are They Used For?

Lucy Bell-Young

by Lucy Bell-Young

28th April 2021

Disinfectants are liquid solutions used to kill or inactivate microorganisms, including viruses, thereby preventing them from infecting humans. Disinfectants are classified into several chemical types and can also be categorised based on their potency or effectiveness.

Why Do We Use Disinfectants?

To protect patients and hospital workers

Technically, disinfectants are considered hazardous substances as they can damage the skin, eyes, and, if ingested, respiratory system. Nonetheless, disinfectants are an important part of our day-to-day lives. They’re most commonly used in clinical settings, particularly in hospitals and microbiology laboratories, where medical equipment and protective clothing need to be disinfected before and after performing surgeries.

Hospital rooms and other medical facilities also need to be regularly disinfected to prevent infections. Even common bacteria and fungi can be fatal to patients with weakened immune systems. To stop infections among patients with compromised health, as well as to stop healthy people becoming sick, it’s crucial that hospital rooms are thoroughly disinfected, including everything from floors, beds and tables to chairs, stairs, door knobs, and all other surfaces. Otherwise, hospitals will become petri dishes for bacteria. 

Gloved hands spraying surface with disinfectant

To prevent the spread of disease

We are all now ultra-aware of the importance of disinfectants due to the coronavirus pandemic. They’re part of the first line of defence against SARS-CoV2 that causes COVID-19.

In response to the virus, disinfectants are now standard in all business establishments and government offices. Disinfectants are also now more commonly used at home. In the fight against the pandemic, disinfectants are among the standard weapons to combat the spread of infection.

Public transportation like taxis, buses, trains, and airplanes can become vectors of COVID-19 if they’re not regularly disinfected. This is because on surfaces that aren’t regularly cleaned, the virus can be viable for several hours or even days. Based on scientific studies, here’s a partial list of the survival time of coronavirus on various surfaces:

  • Metal: The virus can be viable for up to five days on metal surfaces like doorknobs, jewelry, and silverware
  • Wood: The viability of the virus on wood surfaces, such as furniture and decking, is up to four days
  • Plastics: The virus can live on plastic surfaces, such as milk containers, backpacks, elevator buttons, and bus seats, for between two and three days
  • Stainless steel: The virus could last from two to three days on stainless steel surfaces like refrigerators, pots, pans, and sinks
  • Cardboard: Cardboard offers a relatively short time of viability for the virus, lasting only up to 24 hours
  • Copper: Copper has antiviral properties that eradicate the virus on its surface within four hours. Pennies, teakettles, and other cookware are some examples of objects that have copper in them. The knowledge of the antimicrobial properties of copper and copper alloys is ancient, even predating the discovery of microbes. Ancient people realized that perishable food and drinks lasted longer in copper containers compared to other types of containers. The reason for this is that copper produces ions that bombard the cell membrane or viral coating of a microbe, rupturing it. The RNA and DNA contents are then destroyed by the free radicals
  • Aluminium: The virus can last from two to eight hours on aluminium surfaces like soda cans, tinfoil, and water bottles
  • Glass: The virus is viable for up to five days on glass surfaces, including drinking glasses, mirrors, and windows
  • Ceramics: Surfaces of things like ornaments, vases, dishes, and mugs can harbour the virus for up to five days
  • Paper: The length of viability time for the virus widely varies on paper surfaces, depending on the strain and on the type of paper. Some strains can last for only a few minutes, while others stay viable for up to five days

To prepare food hygienically

The Food Standards Agency (FSA) estimates that each year, approximately 2.4 million people in the UK become sick because of food poisoning brought on by microorganisms. Of those, around 180 people die every year because of food-borne pathogens. Most of those who die are seniors above 75-years-old. The top five pathogens that cause deaths are:

  • Campylobacter
  • Clostridium perfringens
  • Listeria monocytogenes
  • Salmonella
  • Norovirus

These microbes are responsible for 98% of the 180 deaths. However, the total number of deaths per year could be as high as 359. The situation could be worse without proper and strict implementation of disinfection standards in food handling equipment, machinery, and packaging.

Graphic showing survival time of covid-19 on different surfaces

What Types of Chemical Disinfectants Are There?

Disinfectants can be classified into several categories based on their active chemical ingredients. These chemicals also have varying strengths and specific uses. Their effectiveness, kill time, ease of use, and safety also vary. Some require special protective suits to handle.

Regardless of the type of disinfectant, the basic principles of why they work are the same. A disinfectant destroys the cell membrane or viral coating. The DNA or RNA strands are also destroyed in the process. As a result, the genetic materials are spilled, killing the microbes. 

Here are some categories of disinfectants:

  • Air disinfectants: Various types of solutions, such as bleach, can be dispensed as mist, vapour or aerosol. These are particularly effective at reducing the number of microbes in the air. Glycols, specifically, are effective at inactivating diverse bacteria, influenza virus, and Penicillium chrysogenum in the air
  • Alcohols: Typically, isopropyl alcohol and ethyl alcohol are used as hand sanitisers. The most effective concentration is at 70%. Alcohols are effective at inactivating the lipid envelopes of bacteria and viruses like HIV, hepatitis B, and hepatitis C
  • Aldehydes: Aldehydes have microbicidal, sporicidal, and fungicidal properties. Formaldehyde and glutaraldehyde are used as disinfectants in laboratories
  • Oxidizing agents: Some examples include ozone, hydrogen peroxide, chlorine, and potassium permanganate. As the name suggests, these substances remove electrons from the cell membranes through the oxidation process, resulting in cell lysis
  • Phenolics: These are the active ingredients in many household disinfectant products, including mouthwashes and disinfectant soaps. One common active ingredient of throat disinfectant, for example, is amylmetacresol
  • Quaternary ammonium compounds: These are a large group of related organic compounds. They’re good in inactivating non-enveloped viruses like norovirus, rotavirus, or the polio virus. They’re mixed in alcohol solutions at 200 ppm and can kill pathogenic fungi, a wide range of bacteria, and mycobacteria. These compounds are commonly used in hospitals
  • Metals: Some metals like silver, copper, zinc, aluminium, nickel, and gold have an oligodynamic effect. They react with thiol or amine groups of proteins in microbes, causing cellular breakdown. They create free radicals or ions that destroy the organic constituents of microorganisms
Person in hazmat spraying air disinfectant in lab

What Are the Uses of Disinfectants?

Disinfectants are used in hospitals, business establishments, government institutions, schools, and in homes to kill or reduce the number of pathogens, thereby preventing disease. Medical instruments and PPE also need to be disinfected to protect healthcare workers and their patients from pathogens.

Many industrial processes, such as food manufacturing, processing, and food preservation, require the machines used in production to be disinfected. Animal domestication also requires disinfections, especially in large-scale hog raising, poultry, and cattle farming, where diseases can easily decimate a large animal farm without disinfection protocols.


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