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Air systems treatment guidelines
On February 11, 2020, WHO announced that re- staphylococci (cocci arranged in clusters); strepto-
spiratory disease caused by the new coronavirus cocci (cocci arranged in chains); streptobacilli (ba-
was called COVID-19 (Corona Virus Disease). The cilli arranged in chains)
2020 pandemic has put the spotlight on the impor- • vibrions, comma shape
tance of sanitation of areas, understood as a set of • Spirilli, spiral shape
surfaces and equipment for air treatment. • spirochete, corkscrew
Climate and Covid Bacteria also divide according to their possibility to
live or not in the presence of oxygen. They are:
With the ISS (Istituto Superiore di Sanità/Higher • aerobic: they breathe oxygen and live in an envi-
Institute of Health) report no. 33/2020 of 25 May ronment where oxygen is present. They grow only
2020, “Indications on ventilation/air conditioning in the presence of O2.
systems in non-sanitary community facilities and • anaerobic: they live in oxygen-free environmen-
in domestic environments in relation to the spre- ts, and die if they are placed in an environment with
ad of SARS-CoV-2 virus” reference to sanitization oxygen. They are, for example, intestinal bacteria.
as the sum of two phases, a thorough cleansing, • other anaerobes: they live and grow even in the
during which dirt and organic material are remo- absence of O2, but their growth is faster in the pre-
ved from the surfaces, followed by an effective sence of 02.
disinfection. There are several publications regar-
ding the products to be used for cleaning and disin-
fection operations, and over time they have become Bacteria and health risks
increasingly specific. We just mention one of the One of the most dangerous bacteria we can find in
most recent, the ISS Covid-19 Report No. 19 dated the environments intended for human use, is Le-
April 25, 2020: gionella. Legionella is a microorganism commonly
“The ECDC (European Center for Disease Preven- found in nature, where it is mainly associated with
tion and Control) guidelines reports that, in princi- the presence of water, whether it be rivers, lakes,
ple, cleaning with water and normal cleaners and reservoirs, thermal springs or human use when it
disinfection with common disinfectant products is flows out of our taps. Today, the infections caused
per sé sufficient, as a first intervention, for the de- by Legionella are a serious problem and concern
contamination of surfaces even if no specific evi- due to the ever-increasing presence of the bacteria
dence of their effectiveness on SARS-CoV-2 is still in the hot water of our homes, hotels, campsites,
available.” swimming pools, hospitals, nursing homes, and in
There is also a regulatory reference, UNI EN 15780 any situation where the water temperature is at le-
“Ventilation of buildings - Pipelines - Cleaning of ast 25°C. It certainly does not help the return of
ventilation systems”, which describes the ways to centralized systems and large volumes of accumu-
evaluate and clean the ventilation systems of bu- lation of domestic hot water, due in some cases to
ildings. Therefore, it emerges once again that the the presence of solar systems, thus putting in di-
operations, in strict order, of cleaning and disin- scussion the safety also in the residential sector,
fection are indissoluble. where Legionella risk is increasingly high. But not
Bacteria only ... High and dangerous concentrations can be
detected even in air conditioning units made up of
Bacteria are unicellular microorganisms that, ba- cooling towers, evaporative coolers or air humidi-
sed on the shape they have, take different names. fiers. We are often faced with this problem in exi-
Their classification is wide: they are divided both sting systems where there are already many issues
according to their ability to survive with or without such as corrosion, limescale, dead circuit branches
oxygen and depending on the physical-pathologi- in which there is no continuous water circulation,
cal aspect. To study them it is necessary to set up and accumulations are not regularly monitored, all
a growth medium that allows to evaluate growth, these are aspects that favour the growth of Legio-
number, speed and motility, but not only. The infor- nella itself.
mation that is obtained allows also to understand
the virulence of the bacteria and consequently its
importance in therapeutic and prognostic terms.
If distinguished by their shape, they are called:
• bacilli, stick shape
• cocci, if they are spherical: diplococci (2 cocci);
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