Disinfecting Surfaces: Porous vs. Nonporous vs. Food Contact

Disinfecting different types of surfaces depending on pores and if they're food surfaces.

Not all surfaces are created equal, at least when it comes to disinfecting and sanitizing them from serious pathogens like coronavirus (COVID-19).

In our experience, one of the most common mistakes people make is using one type of disinfectant thinking that it will work for every type of surface.

Important: Avoid Using the Wrong Chemicals When Disinfecting Different Surfaces

It’s important to read the information on the product label of any chemical disinfectants that you plan to use. Some disinfectants can only be used on one type of surface, while others may be used on multiple types of surfaces.

Using a disinfectant on the wrong type of surface may result in the incomplete elimination of pathogens and possibly also cause damage to the surface.

The product label will tell you what types of surfaces the disinfectant can be safely used on. You can also find the types of surfaces for a given disinfectant using the table found on the EPA’s List N.

When it comes to sanitizing and disinfecting COVID-19, there are 3 primary surface types to be aware of:

  • Porous (P)
  • Hard Nonporous (HN)
  • Food Contact Surfaces (FCR or FCNR)

Understanding what each of these surface types means, and what the difference is, will help you select the right disinfectant product for your specific needs.

What Are “Porous” Surfaces?

Porous surfaces (P) are made from materials that naturally have small holes, or pores, inside them. These pores allow the material to hold or absorb air, water, and other liquids.

One general rule of thumb is that if a surface can absorb or allow liquid to pass through, it’s porous.

Many soft surfaces are considered porous, such as paper, cardboard, carpet, and fabric. Not only do these surfaces tend to get dirty more easily (since dirt and debris can get trapped in the pores), they also allow germs and pathogens to survive for longer periods of time.

When using disinfectant chemicals that are not meant for porous surfaces, the chemicals can stain or damage the material after becoming trapped in these pores.

Hard surfaces can also be porous. Examples of hard, porous surfaces include untreated wood, granite, and certain types of plastics.

When treated with a moisture-resistant coating, these surfaces can sometimes appear to be nonporous. But in fact, improperly using the wrong type of disinfectant can sometimes corrode and destroy these coatings before staining or damaging the porous surfaces underneath.

Common active ingredients in EPA-registered disinfectants for SARS-CoV-2 used on Porous (P) surfaces include:

  • Hydrogen peroxide
  • Peroxyacetic acid
  • Quaternary ammonium
  • Sodium carbonate peroxyhydrate
  • Tetraacetyl ethylenediamine

What Are “Hard Nonporous” Surfaces?

As the name suggests, hard nonporous surfaces (HN) are rigid and without pores. Examples of hard nonporous surfaces include stainless steel, metal, glass, hard plastic, and varnished wood.

These types of materials are impervious to water, and generally easier to wipe clean compared to porous materials.

Hard nonporous surfaces make up the majority of shared, high-touch surfaces amd areas that require the most attention when it comes to sanitizing and disinfecting COVID-19. Examples include doorknobs, handles, chairs, countertops, bathrooms, electronics, and appliances.

Certain nonporous surfaces can be soft as well, such as leather, vinyl, and rubber. Disinfectants designated for hard nonporous (HN) surfaces shouldn’t be used on these materials unless it’s specified.

Otherwise, follow the recommended cleaning and disinfecting instructions for each type of soft nonporous surfaces. If you can’t find this information, a good option in the interim is to gently wash the surface with soap and water.

Common active ingredients in EPA-registered disinfectants for SARS-CoV-2 used on Hard Nonporous (HN) surfaces: include

  • Chlorine dioxide
  • Citric acid
  • Dodecylbenzenesulfonic acid
  • Ethanol (alcohol)
  • Glycolic acid
  • Hydrochloric acid
  • Hydrogen peroxide
  • Quaternary ammonium
  • Hypochlorous acid
  • Iodine
  • Isopropanol (isopropyl alcohol)
  • L-Lactic acid
  • Peroxyacetic acid
  • Phenolic
  • Potassium peroxymonosulfate
  • Silver ion
  • Sodium chlorite
  • Sodium dichloroisocyanurate
  • Sodium hypchlorite
  • Thymol
  • Triethylene glycol

What Are “Food Contact” Surfaces?

Proper disinfection of food contact surfaces is especially important during a pandemic and helps ensure that your food is safe to eat. EPA-registered disinfectants for COVID-19 that can be used on food contact surfaces must meet certain criteria regarding safety and efficacy.

The term “food contact surface” is defined as any type of surface or object that comes into contact with food, both directly or indirectly. This can include plates, cups, pots, pans, cutlery, containers, food appliances, dining tables, and other common surfaces found in homes, kitchens, cafeterias, restaurants, and bars.

There are two types of disinfectant products approved for use on food contact surfaces. These are designated on their label for either “Food Contact Surfaces, Post-Rinse Required” (FCR) or “Food Contact Surfaces, No Rinse” (FCNR).

As the name indicates, disinfectants labeled FCR require surfaces to be rinsed after being disinfected. If the disinfectant is labeled FCNR, a rinse is not necessary.

For FCR surfaces, only rinse after the required contact time, or dwell time, as indicated on the disinfectant product label.

General Tips for Disinfecting Surfaces

  • Identify and prioritize disinfecting frequently-touched surfaces
  • Check that the disinfectants used are EPA-registered and appropriate for the intended surfaces.
  • Do not mix disinfectant products or chemicals.
  • Clean surfaces with soap and water first to remove dirt and debris before disinfecting.
  • Open windows and/or doors to ensure adequate ventilation.
  • Wear appropriate PPE, including disposable gloves and face coverings.
  • Avoid touching your face or electronics while using disinfectant chemicals.
  • After disinfecting, allow the disinfectant solution to remain wet on the surface for a designated period of time (“dwell time”) before wiping or drying.
  • Wash hands for at least 20 seconds with soap and water after using disinfectant chemicals.
  • Make sure that all disinfectant products are properly labeled and safely stored.