Viability of COVID-19 on Various Types of Surfaces

SARS-CoV-2 is the coronavirus that causes COVID-19, which has been a significant public health concern since early 2020 that has quickly led to a world-wide pandemic. The coronavirus that causes COVID-19 mainly spreads from person to person by transmission of larger droplets from sneezes and coughs. However, there is also growing evidence that smaller particles called aerosols can hang in the air longer and travel farther. These aerosols may play a part in transmission by direct contact with the suspended airborne aerosols by the mouth, nose, or eyes. Also, the aerosols could settle onto surface materials and be indirectly transmitted by touching the virus-impacted surface and subsequently touching your mouth, nose, or eyes.

The role of environmental surface materials contaminated with SARS-CoV-2 for disease transmission remains unclear. Because contamination of environmental surface materials and subsequent viral transmission to humans is of concern, several studies are evaluating how long the virus stays alive on a variety of surfaces and increases the risk of infection by contact transmission. Although it is still unclear if the risk of transmission is increased, from what is currently known, transmission from contact with surfaces is a much lower risk than person to person. Still, it is possible (though not as likely) to catch the virus if you touch a surface or object that has the virus on it and then touch your mouth, nose, or eyes.

This article provides the reader with the current results of one investigation into the viability of the SARS-CoV-2 virus on various environmental surfaces. This information can assist the reader in addressing the potential of viral transmission by direct contact with various surfaces within the indoor work environment in the preparation of a Health and Safety Plan (HASP), a Job Hazard Analysis (JHA), an Activity Hazard Analysis (AHA), or a Job Safety Analysis (JSA).

Article and Image Credit

One of the recent published articles on the topic of SARS-CoV-2 viability on various surfaces is “SARS-CoV-2 Viability on 16 Common Indoor Surface Finish Materials” by Shannon E. Ronca, PhD, MPH; Rodney X. Sturdivant, PhD; Kelli L. Barr, PhD; and Debra Harris, PhD, all associated with the Baylor College of Medicine or Baylor University. The article was published on February 23, 2021 in “Health Environments Research & Design Journal”. A very condensed general summary of the test methods and results is included herein. The reader is referred to the article at the link previously referenced for more detailed information on the methodology and results of this study.

In this study, the authors investigated the stability and degradation of SARS-CoV-2 on 16 common indoor surface materials (Table 1). These test materials were selected based on their substantial and common use in the indoor environment, specifically in healthcare, education, public, and residential environments. A mix of high touch (i.e., stainless-steel, solid surface, and high-pressure laminate) and low touch (i.e., rubber flooring, luxury vinyl tile flooring, and vinyl wall covering) surfaces were included in the selected surface materials. Each material was cut to 2-inch by 2-inch samples, and prepared by initial cleaning and removal of any adhesives, paper, or other material. Samples were provided to the laboratory in triplicate with additional samples of each type of material for additional testing as needed.

Table 1. Environmental Surface Materials Tested for Viability
 of SARS-CoV-2 Under Laboratory Conditions

Material

Description

Acrylic solid surface

Solid, non-porous, homogeneous, composed of acrylic resin and natural minerals.

Solid surface with CuO

Solid, homogeneous, anti-microbial sheet composed of polyester resins, mineral fillers, and pigments. Cupric oxide (CuO) is added for anti-microbial properties.

Stainless-steel, brushed

Chromium–Nickel (CrNi) austenitic alloy sheet with 18 percent (%) minimum chromium and 10% maximum nickel, 18-gauge, grade 304.

High-pressure laminate

Decorative surface papers impregnated with melamine resins pressed over kraft paper core sheets impregnated with phenolic resin.

Copper sheet

Copper Alloy C71000 (Copper Nickel, CuNi) composed of 78%-84% copper and 19-23% nickel, 18 gauge.

Quartz

Primarily a natural material with about 7% polyester resin binder and pigment.

Rubber flooring

Vulcanized rubber (natural, synthetic, recycled) commonly with a polyurethane top layer.

Vinyl, sheet, homogeneous

A single layer of polyvinyl chloride (PVC) with a urethane topcoat.

Wood laminate flooring, commercial

Laminated layered flooring system using timber veneer backer board, HDF core, and solid wood wear layer, and may be finished with a urethane coating.

Luxury vinyl tile (LVT) #15

LVT, glue down floor installation, flexible PVC core, stabilization layer.

Luxury vinyl tile #21

LVT, floating floor installation, flexible PVC core, stabilization layer, cushion backing, waterproof.

Luxury vinyl tile #26

LVT, glue down installation, flexible PVC core, no stabilization layer, no cushion backing.

Carpet, commercial

Nylon 6, 20-ounce level loop, polyester backing.

Carpet, residential

Polyethylene terephthalate (PET), 25-ounce weight, cut pile, jute backing.

Upholstery, non-woven

Application for seating, 100% polyurethane non-woven face with polyester backing. Weight 15 ounce. Performance for abrasion 100,000 double rubs.

Vinyl wall covering, type II

Commercial grade wall covering, 20-ounce weight, two layers of solid vinyl applied to a woven or non-woven fabric substrate. Composition includes plasticizers, stabilizers, and pigments. May contain biocides and flame retardants.

Each sample of surface materials was inoculated with 10,000 plaque-forming units (PFU) of SARS-CoV-2 in 50 microliters (µL) and spread evenly across the surface. The surfaces were left to dry at a temperature of 25 degrees Celsius (°C) and a relative humidity of 45 to 50%. At 4, 8, 12, 24, 30, 48, and 168 hours post infection (hpi), samples were washed with 450 µL of cell culture media and frozen at −80 °C. Viral titers were determined for each sample and time point by standard plaque assay.

Each material was tested in triplicate. Table 2 shows the data set of the average of infectious virus, presented as PFU per 50 µL at each time point for each material. One PFU is defined as one infectious viral particle.

Table 2. Calculated PFUs per 50 µL at Each Time Point
for the Entire Two-Inch by Two-Inch Sample

Material

4 hrs

8 hrs

12 hrs

24 hrs

30 hrs

48 hrs

168 hrs

Acrylic solid surface

410 ± 3

295 ± 25

105 ± 11

21 ± 2

0

0

0

Solid surface with CuO

0

0

0

0

0

0

0

Stainless-steel, brushed

495 ± 76

130 ± 57

0

0

0

0

0

High-pressure laminate

305 ± 118

0

0

0

0

0

0

Copper sheet

0

0

0

0

0

0

0

Quartz

330 ± 33

243 ± 3

106 ± 34

23 ± 12

0

0

0

Rubber flooring

390 ± 3

0

0

0

0

0

0

Vinyl, sheet, homogeneous

327 ± 25

57 ± 4

0

0

0

0

0

Wood laminate floor, commercial

245 ± 22

0

0

0

0

0

0

Luxury vinyl tile #15

242 ± 18

131 ± 29

90 ± 9

0

0

0

0

Luxury vinyl tile #21

100 ± 2

30 ± 5

0

0

0

0

0

Luxury vinyl tile #26

192 ± 2

5 ± 0

0

0

0

0

0

Carpet, commercial

115 ± 6

0

0

0

0

0

0

Carpet, residential

170 ± 20

12.5 ± 2

0

0

0

0

0

Upholstery, non-woven

230 ± 40

45 ± 17

0

0

0

0

0

Vinyl wall covering, Type II

195 ± 62

137 ± 6

100 ± 14

35 ± 7

12 ± 0

10 ± 2

0

As indicated in Table 2, the material with the most infectious virus in the group was “stainless-steel, brushed” with about 5% of the original 10,000 PFUs remaining after four hours. However, no PFUs were detected on stainless-steel at 12 hpi. No PFUs were detected on two materials (“Solid surface with CuO” and “Copper sheet”) after the first interval tested at four hpi. PFUs were not detected on the surfaces of 12 materials after eight to 12 hpi. The only three materials on which PFUs were detected at 24 hpi were “Acrylic solid surface”, “Quartz”, and “Vinyl wall covering, Type II”. Vinyl wall covering was the only material on which PFUs were detected after 24 hpi, with PFUs detected after 48 hpi, but none were detected at the next testing interval at 168 hpi.

The authors of the referenced study grouped the various tested materials into four categories based on the “time to no infectious materials”. As indicated in Table 3, Categories 1 through 4 consisted of materials that did not have infectious particles detected at four hpi (two materials), at eight hpi (four materials), at 12 hpi (six materials), and more than 12 hpi (four materials), respectively. The Category 4 group of materials generally are those with the slower rate of infectious virus decay.

Table 3. Categories of 16 Materials Based on Time to No Infectious Particles.

Category 1

4 hours

Category 2

8 hours

Category 3

12 hours

Category 4

after 12 hours

Solid surface with CuO

High-pressure laminate

Stainless-steel, brushed

Acrylic solid surface

Copper sheet

Rubber flooring

Vinyl, sheet, homogenous

Quartz

 

Wood laminate flooring, commercial

Luxury vinyl tile #21

Vinyl wall covering,

type II

 

Carpet, nylon, commercial

Luxury vinyl tile #26

Vinyl flooring #15

 

 

Carpet, residential

 

 

 

Upholstery, non-woven

 

So, the takeaway from this study is that the viability of the SARS-CoV-2 virus on 16 common indoor surfaces varies depending on the material. The “time to no infectious particles” ranges from less than four hours to more than 48 hours (but not exceeding 168 hours), depending on the material. Higher temperatures and relative humidity can increase the rate of decay of SARS-CoV-2 affecting transmission capability so the results summarized in this study may vary depending on the environmental conditions. Also, research into this topic is on-going and most likely will result in conclusions that may differ from those in this study. Nonetheless, the results of this study can provide some general information so that one can make informed decisions when addressing the potential of viral transmission from surfaces in an indoor setting during the preparation of a Health and Safety Plan (HASP), a Job Hazard Analysis (JHA), an Activity Hazard Analysis (AHA), or a Job Safety Analysis (JSA).

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