Viruses, Bacteria, and Mold

Problems with microbes?

Mold, bacteria, and viruses can cause problems in any household. While not all microbes are bad, some are capable of compromising your health and causing disease. Mold and mildew can produce allergens that can exacerbate respiratory problems, and pathogenic bacteria and viruses are responsible for giving you everything from the common cold to food-borne illnesses.

See PRI’s Top-Ten List for Keeping Pests Out and Kids Safe. Use PRI’s tool, PestSmart, to find low-hazard pesticide products.

Preventing and Managing Mold, Bacteria, and Viruses

Cleaning is a top-level strategy for removing mold and bacteria. This work can be quite a chore, but is necessary to keep yourself and your family healthy. A few additional steps can be taken to reduce the possibility of these microbes causing a problem around your home.

Utilize natural light and circulating air

  • Open a window or turn on a fan to move moist air out and reduce the likelihood of mildew forming in the bathroom. Mold and mildew are often a problem in bathrooms because of the moisture.
  • Use the sun: UV rays can kill bacteria, and leaving items exposed to strong sunlight for several hours can help to disinfect them.

Stop mold from growing by fixing leaks right away

  • Fix leaky pipes or water spills right away to help make sure that mold never has a chance to start growing.
Practice clean kitchen techniques
  • Ensure that raw foods such as meat are kept separate from other foods in the refrigerator to avoid intestinal problems caused by foodborne illnesses.
  • Clean counters and cutting boards thoroughly after they have come into contact with raw foods. If a cutting board is not dishwasher safe, clean it thoroughly with warm soapy water after use.
  • Make sure that cold foods stay cold and hot foods stay hot to keep bacteria from growing. Keep your refrigerator at 40°F or below and put leftover food in the refrigerator as soon as possible.
  • Cook meats to the right temperature to make sure they are safe to eat: 145°F for whole meats, 160°F for ground meats, and 165°F for poultry.
Hand Washing

Wash hands

  • Wash hands frequently to help prevent transmission of pathogenic bacteria or viruses. Soap and water are a powerful tool and in most cases are just as effective as antibacterial soaps.

Be careful with children, toys, and pets

  • Keep toys clean. Children’s bath toys can retain water, which encourages the growth of mold.
  • Avoid sharing bath towels. Sharing is not recommended since this can spread bacteria and viruses, especially when someone in the household has a cold.
  • Wash hands after playing with pets or handling pet waste.
Pest Smart mobile app

Read on for information on natural cleaners for mold, bacteria, and viruses. Also included is a comparison of active ingredients commonly used in antimicrobial products.

Interested in finding out more about specific antimicrobial products? The Pest Smart app is now available in the iTunes Store. Conveniently access pesticide data on your iPhone and iPad while on the job, in the store, and at home.

  • Search by product name or registration number.
  • Search by pest to find pesticide products that target common household and garden pests like ants, fleas, cockroaches, lawn weeds and aphids.
  • Quickly verify the eligibility of a pesticide product for use in the LEED v4-certified Integrated Pest Management (IPM) program.
  • Compare products and find least-toxic alternatives to streamline decision-making.
  • Link to PRI’s Pest Management Bulletins to learn about low-impact methods of pest control that minimize pesticide use and exposure.

Low Impact Approaches

Natural Cleaners for Mold, Bacteria, and Viruses

Various combinations of household items such as vinegar, baking soda, and plain soap can be used as cleaning agents in the home and are just as effective as harsher chemical products for many applications. Whether you want to avoid using these harsh chemicals because of asthma or other sensitivities, or are just looking for a cost-effective set of cleaning tools, the following list highlights the most important cleaners.


  • Vinegar works best at full strength (5% acetic acid) but the addition of several drops of essential oil will improve the smell for those that are sensitive. Vinegar is effective for cleaning mildew in the shower or can be used as an after-shower spray to prevent the growth of new mildew. Vinegar can also be used to kill some bacteria and viruses, including Salmonella and E. coli, and is useful for cleaning counters or cutting boards and removing smells.
  • NEVER mix vinegar with bleach or ammonia because it forms harmful chlorine or chloramine gases. Be careful not to clean with vinegar and then with bleach after, as the residue may still react.
Cleaning supplies

Baking soda

  • Baking soda has antifungal properties and is registered by the US EPA as a biopesticide.
  • Mix baking soda with water to make a paste that is effective at removing mold or mildew in the grout between tiles. Baking soda has many properties that make it useful as an all-purpose cleaner and can be used as a scouring agent.

Tea tree oil

  • Tea tree oil is more expensive than some other natural remedies but is effective at killing mold and mildew. After scrubbing off mildew using a tea tree oil solution, apply a little extra to prevent more mildew from growing back.
  • Many bacterial species are susceptible to tea tree oil, including Streptococcus pyogenesStaphylococcus aureus and Escherichia coli.
  • Salt is a microbial inhibitor. Many microorganisms need moist conditions to thrive, making salt an efficient way to reduce the amount of water available for microbes to grow.
  • Salt also interferes with microbe enzyme activity and weakens the molecular structure of bacterial and fungal DNA.


Household hydrogen peroxide

  • A 3% hydrogen peroxide solution can be use to remove and prevent the growth of mildew and mold.
  • Hydrogen peroxide is registered as a sterilizer and is effective against the HIV-1 virus, Hepatitis B, Hepatitis C, Mycobacterium tuberculosis, and Norovirus. Higher concentrations of peroxide are available as cleaning products and are also effective against many pathogenic bacteria and viruses, but are corrosive to skin and eyes.

Lemon juice

  • Lemon juice is a versatile cleaner and can be used in combination with baking soda or salt to inhibit the growth of some bacteria.
  • Using a stronger cleaner is advised for cleansing surfaces that come in contact with raw meat.

Many of these natural cleaners can help reduce problems caused by other household pests as well. Wiping counters with vinegar can kill microbes as well as prevent pests such as ants and cockroaches finding food in your kitchen, without resorting to harmful pesticides.  See our bulletins on ants and cockroaches for more information.

Antimicrobial Pesticides for Treating Mold, Bacteria, and Viruses

Potential Consequences of Using Antimicrobial Pesticides

Antimicrobial pesticides can be beneficial for protecting human health and are required in some institutional settings such as daycare centers, restaurants, and other food handling establishments. If you are caring for an immune-compromised person or running a daycare center, proper disinfection or sanitation of surfaces is particularly important, and antimicrobial pesticides are an important tool. Nevertheless, there are adverse affects associated with their use, such as:

  • The overuse of some antimicrobial agents may be a factor contributing to the development of resistant bacteria, so use only when needed.
  • Because many of these products are available as aerosol sprays, exposure through inhalation is possible and can cause respiratory and eye irritation and exacerbate asthma.
  • Many of these products are effective at sanitizing and disinfecting because they are oxidizing agents or are strongly acidic or basic. These characteristics result in hazards from spills on skin or in the eyes, or via inhalation.

Be sure to follow the label instructions carefully and read all warnings.

Types of antimicrobial pesticides

Antimicrobial pesticides are used to destroy or stop the growth of microorganisms such as bacteria, viruses, and fungi. They are designed to be used on inanimate objects only and can be found as sprays, liquids, concentrated powders, wipes, and gases (mostly for hospital use) .

spray bottles PakTechTK
There are several different types of anti-microbial products and it is important to know their intended use. The US EPA has very specific definitions for each one:
  • Cleaner: A product that physically removes debris from the surface.
  • Sanitizer: A product that kills 99.9% of the germs identified on its label.
  • DisinfectantA product that kills nearly 100% of the germs identified on its label. Destroys most pathogens but not bacterial spores.
  • Sterilizer: A product that destroys all microorganisms, including bacterial spores.

The Centers for Disease Control (CDC) further classifies disinfectants as high, intermediate, and low level disinfectants, which has to do with which particular microorganisms it inactivates and the concentration at which it is active.

The antimicrobial activity of the product is affected by the concentration of the active ingredients and the dwell time.

  • Dwell time: The amount of time that the product must remain on the surface for optimum antimicrobial activity. Typically included on the label.
  • Concentration of active ingredients: The concentration of an active ingredient varies from product to product, so read the label to determine if a product can be used as a disinfectant or only as a sanitizer.The percent of the active ingredient and the inert ingredients in a product may also change the hazards associated with a particular product.

The US EPA registers antimicrobial products and ensures that labels may not make claims about their effectiveness that are not supported by data. They have also compiled a list of registered products that are effective against specific pathogens, including tuberculosis bacteria, HIV-1 virus, and hepatitis C. For the lists of these products and others, see their website on Selected EPA-Registered Disinfectants.

The following table provides the hazards associated with specific active ingredients. Products may contain other ingredients or more than one active ingredients, so be sure to carefully read the label for any additional or different hazard warnings. According to the EPA, there are approximately 275 active ingredients that are used in antimicrobial products, so we have provided a partial list of some of the types of products you may encounter.

Comparison of Antimicrobial Active Ingredients

Lower-Impact Antimicrobial Pesticides

Type of Active Ingredient Representative Chemicals Primary Hazards Effective Against These Pathogenic Bacteria
Alcohols Ethyl Alcohol, Isopropanol Alcohols are eye irritants and can be skin irritants, depending on the concentration. Ethyl alcohol:Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE
Isopropanol: Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE
Botanicals Pine oil, Thymol Pine oil and thymol are eye and skin irritants and can cause eye damage, depending on concentration. Pine oil: None of the most common emerging pathogens, according to the EPA
Thymol: Mycobacterium tuberculosis, HIV-1, MRSA, VRE
Carboxylic acids Caprylic acid (octanoic acid); citric acid; glycolic acid; lactic acid Carboxylic acids are mild to severe eye and skin irritants, depending on concentration.

In a report by the San Francisco Department of the Environment, caprylic acid, citric acid, and lactic acid were identified as among the safer active ingredients available in disinfectant and sanitizer products.

Citric acid: Mycobacterium tuberculosis, HIV-1, Hepatitis B, Norovirus, MRSA, VRE
Caprylic acid: HIV-1, Hepatitis B, MRSA, VRE
Glycolic acid: None of the most common emerging pathogens, according to the EPA
Iodine Iodine; Polyalkyloxy ethanol – iodine complexes Iodine compounds have moderate oral and inhalation toxicity and are corrosive to the skin. They are also highly toxic to aquatic invertebrates. Polyalkoxy ethanol-iodine complexes: Mycobacterium tuberculosis, Hepatitis B, HIV-1
Peroxides Hydrogen peroxide; Peroxyacetic acid; Potassium peroxymonosulfate; Peroxyoctanoic acid Peroxides are corrosive and severely irritating to the eyes and skin, depending on concentration.
Potassium peroxymonosulfate may be highly toxic to birds and it is highly toxic to fish.

In a report by the San Francisco Department of the Environment, hydrogen peroxide was identified as among the safer active ingredients available in disinfectant and sanitizer products.

Hydrogen peroxide: Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE
Peroxyacetic acid: HIV-I, Hepatitis B, MRSA, VRE
Potassium peroxymonosulfate: HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE

Antimicrobial Pesticides with Potential for Significant Adverse Effects

Type of Active Ingredient Representative Chemicals Primary Hazards Effective Against These Pathogenic Bacteria
Biguanide Chlorhexidine diacetate, Polyhexamethylene biguanidine (PHMB) Chlorhexidine diacetate is extremely irritating to the eyes and has moderate inhalation toxicity.
PHMB is severely corrosive to the eyes, irritating to the skin, and a moderate skin sensitizer, depending on the concentration.
Both products are highly toxic to fish and aquatic invertebrates.
Chlorhexidine diacetate: None of the most common emerging pathogens, according to the EPA
PHMB : None of the most common emerging pathogens, according to the EPA
Chlorinated aromatics Triclosan, Triclocarban Triclosan is a suspected endocrine disruptor.
Triclocarban is highly toxic to aquatic organisms, may be persistent in the environment, and may be reproductively and developmentally toxic.
Widespread use of chlorinated aromatics creates resistant populations of bacteria.
Triclosan: None of the most common emerging pathogens, according to the EPA
Triclocarban: None of the most common emerging pathogens, according to the EPA
Hypochlorites and Triazinetriones Sodium hypochlorite; Calcium hypochlorite; Sodium chlorite; Hypochlorous acid; Sodium dichloro-s-triazinetrione; Trichloro-s-triazinetrione; Sodium and calcium hypochlorite are extremely corrosive and can cause eye and skin damage, have moderate oral toxicity, may be skin sensitizers and may exacerbate asthma or respiratory problems.
They are also highly toxic to aquatic life.
When bleach is mixed with acids or ammonia it can release chlorine or chloramine gas, which are very toxic.
Sodium.hypochlorite:Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE
Sodium chlorite: Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE
Hypochlorous acid: Mycobacterium tuberculosis, HIV-1
Sodium dichloro-s-triazinetrione: HIV-1, MRSA, VRE
Trichloro-s-triazinetrione: None of the most common emerging pathogens, according to the EPA
Inorganic Hydrochloric acid (HCl); Phosphoric Acid; Sodium bisulfate; Sodium hydroxide; Sodium bromide; Bromine Hydrochloric and phosphoric acid are corrosive to the eyes and skin.
Sodium bisulfate is corrosive to the eyes only.
HCl: Mycobacterium tuberculosis, HIV-1, MRSA, VRE
Phosphoric acid: HIV-1, MRSA, VRE
Sodium bisulfate: None of the most common emerging pathogens, according to the EPA
Sodium hydroxide: HIV-1
Sodium bromide : HIV-1
Bromine : None of the most common emerging pathogens, according to the EPA
Phenols Ortho-phenylphenol (OPP); Chloroxylenol; Para-tert-amylphenol; Ortho-benzyl-para-chlorophenol OPP is a probable carcinogen and possible endocrine disruptor; Chloroxylenol can cause eye damage and skin irritation.
Para-tert-amylphenol is corrosive to the eyes and some studies suggest that it may be an endocrine disruptor.
Ortho-benzyl-para-chlorophenol is corrosive to the eyes and skin and is classified as a possible human carcinogen.
OPP: Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, MRSA, VRE
Chloroxylenol: HIV-1, Hepatitis C
Para-tert-amylphenol : Mycobacterium tuberculosis, HIV-1, MRSA, VRE
Ortho-benzyl-para-chlorophenol : HIV-1, Hepatitis B, MRSA, VRE
Quaternary Ammonium Compounds Alkyl dimethyl benzyl ammonium chloride (ADBAC); Didecyl dimethyl ammonium chloride (DDAC) ADBAC and DDAC can be corrosive to the skin and eyes, can exacerbate asthma or respiratory problems, and have moderate oral and inhalation toxicity.
They are also highly toxic to aquatic life.
ADBAC: Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE
DDAC: Mycobacterium tuberculosis, HIV-1, Hepatitis B, Hepatitis C, Norovirus, MRSA, VRE
Silver Compounds Metallic silver (nanoparticles), silver oxide, Silver sulfate, Silver nitrate Exposure to large amounts of silver compounds can cause skin irritation or sensitization.
Silver salts are highly toxic to aquatic life.
Metallic silver: Mycobacterium tuberculosis, HIV-1, Norovirus, MRSA, VRE

Definitions: MRSA= Methicillin-resistant Staphylococcus aureus, VRE=Vancomycin-resistant Enterococcus, HIV=Human Immunodeficiency Virus.

Regulatory Update on Antimicrobial Pesticides

In December 2013, the Food and Drug Administration (FDA) issued a proposal to require antibacterial hand soaps and body washes to prove that their products are safe for regular use. Despite there being no data that demonstrates that antibacterial products are any more effective than regular soap and water, these products are used widely. This new requirement to improve safety should help ensure that risks associated with the use of these products is low. For more information, see the FDA News Release.

References and Additional Resources

The City of San Francisco recently released a report developed by the Responsible Purchasing Institute which evaluated safer disinfectants and sanitizers based on criteria including hazards to human health and hazards to the environment. The document, Safer Products and Practices for Disinfecting and Sanitizing Surfaces, provides information about active ingredients, as well as a list of products that are safer to use and information about all the products that were reviewed. For a list of registered products, see PRI’s Pesticide Product Evaluator.

More recommendations on how to protect yourself and your family from disease-causing bacteria and viruses can be found at the following websites: