Coronavirus and surfaces
As has been mentioned several times during the pandemic, coronavirus (SARS-CoV-2) mostly spreads through small drops of saliva (droplet) that infected people emit by coughing, sneezing, speaking loudly and sometimes breathing. These drops containing millions of viral particles tend to remain little in the air and fall on the surfaces by gravity: the infection can therefore occur by coming into direct contact with the droplet issued by someone, or by touching the surfaces on which the drops have settled. In the latter case, you must then touch your face (mouth and eyes) to be infected.
It is because of these methods of transmission of the coronavirus that it is recommended to keep a distance of at least one meter from the next, in order to reduce the risk of coming into direct contact with the droplets, and to wash your hands well and frequently, to avoid getting infected after touching contaminated surfaces. Surfaces can therefore be an important means of contagion, even if to date there are still not enough clear elements to determine how much contact with handles and other contaminated objects increases the risk of contagion.
Several researches in recent months have tried to measure the ability of the coronavirus to remain on surfaces, after the droplet that contain them. The estimates available so far vary widely and range from less than an hour to a week, depending on the surfaces and other environmental conditions. However, it is good to remember that the presence of traces of coronavirus on a surface does not imply that the virus is still active, and therefore capable of causing an infection when it comes into contact with the mucous membranes of our respiratory tract.
On the basis of the knowledge and experiments carried out so far, some estimates can be made on the permanence of the coronavirus based on the type of surface. The table below shows how long the presence of coronavirus infecting particles was detected and how long it was no longer possible to detect them.
Cleaning and sanitizing
The cleaning of the surfaces must be carried out frequently and with particular precautions especially on the workplaces, for example providing for sanitization at the end of each shift, so that workers who take turns run less risks of being infected by those who preceded them. The Ministry of Health has identified a sequence of eight activities to be carried out to sanitize the environments:
1. Normal ordinary cleaning with soap and water reduces the amount of virus present on surfaces and objects, reducing the risk of exposure.
2. Cleaning of all surfaces of furniture and work equipment, machines, tools, etc., as well as handles, baskets, etc. it must be done at least after each turn.
3. The risk of exposure is reduced even more if disinfection procedures are carried out using authorized disinfectants with virucidal action (PMC or biocides). Frequent disinfection of surfaces and objects is important when touched by several people.
4. Disinfectants kill germs on surfaces. By disinfecting a surface after cleaning, it is possible to further reduce the risk of spreading the infection. The use of authorized disinfectants represents an important part of reducing the risk of exposure to COVID-19.
5. Disinfectants must be used responsibly and appropriately according to the information on the label. Do not mix bleach and other cleaning and disinfection products together: this can cause fumes that can be very dangerous if inhaled.
6. All detergents and disinfectants must be kept out of the reach of children.
7. The hoarding of disinfectants or other materials for disinfection can lead to a shortage of products that could instead be used in particularly critical situations.
8. Suitable gloves must always be worn for the chemicals used during cleaning and disinfection, but additional personal protective equipment (PPE, especially for professional products) may be required depending on the product.
However, some exceptions may apply to general guidelines. For example, if a shop, office or company has been completely closed and without people passing through it for at least 7-10 days, (unless specific indications) it is sufficient to proceed with an ordinary cleaning because the coronavirus does not resist outside an organization for more than a week, based on research done so far.
Hard, soft and porous surfaces
The circular recommends paying particular attention to the most at risk surfaces such as: door handles, light switches, telephones, computers, taps and sinks and touchscreen screens. They are objects with which many people come into contact, especially in places such as offices, shops and companies, and it is therefore important that they are disinfected with greater diligence and accuracy.
In addition to washing with water and detergents, including disinfectants, it can be useful to remove soft and porous materials from the rooms (carpets, furnishings with fabric covers) to make cleaning easier. It is also recommended to eliminate unnecessary furnishings, in order to free up spaces in the working environments and therefore favor the practices of physical distancing, both among workers and between customers, in the case of commercial establishments.
Hard surfaces and glass, metal and plastic objects can be cleaned by first washing with soap and water, followed by disinfectant to make the viruses inactive. Soft and porous materials (carpets, rugs and chairs) are more difficult to wash and disinfect and therefore may need to be covered with plastic, washable or disposable sheets.
In general, less precautions can be applied to external surfaces by carrying out normal cleaning with water and detergents. In the case of bars and restaurants with outdoor spaces, it is important that tables and chairs are disinfected, and any objects that can be touched by staff and customers are disinfected.
As the Ministry of Health had already explained in a previous circular, to date there is no scientific evidence on the usefulness of spraying disinfectant on the sidewalks and on the street to reduce the risk of infection. While the benefits have not been demonstrated, the danger of the practice has been highlighted above all for the environment.
Detergents and disinfectants
The Istituto Superiore di Sanità published a document a few weeks ago in which it illustrates in detail the various types of disinfectants, indicating the most suitable ones not only for surfaces, but also for personal use to sanitize hands, for example. In principle, individuals can use the hand sanitizing gels found in the pharmacy, following the instructions on the package. Alcohol or sodium hypochlorite products (what we call “bleach”) are indicated for the sanitization of surfaces, making sure that they are used at the right concentration: usually 70 percent for ethyl alcohol and 0.1 for one hundred for sodium hypochlorite.
For about ten days, the clothing stores have also reopened, leading to some further doubts about the risks and methods of disinfection both by merchants and those who frequent those environments to shop. Stores must be subjected to daily treatments for cleaning (or sanitizing where required) and with a few more precautions than in other places, given the influx of people and the fact that the clothes on sale are touched and worn to try them on.
The dressing rooms must be sanitized frequently, and customers should be provided with hand sanitizers, gloves and masks when entering the shop. The clothes can be sanitized using dry steam, not being able to proceed with more invasive treatments that could ruin them. The shopkeepers could also consider having clothes that have not yet been sold but have been tried several times dry cleaned.
Distance and clean hands
More generally, and as it has been doing for some time now, the Ministry of Health advises to always proceed with great caution and to avoid any initiative that could lead to an increased risk of being infected. Physical spacing remains the main resource, especially when combined with frequent and careful hand washing.