Air systems treatment guidelines

On February 11, 2020, WHO announced that re-

spiratory disease caused by the new coronavirus

was called COVID-19 (Corona Virus Disease). The

2020 pandemic has put the spotlight on the impor-

tance of sanitation of areas, understood as a set of

surfaces and equipment for air treatment.

Climate and Covid

With the ISS (Istituto Superiore di Sanità/Higher

Institute of Health) report no. 33/2020 of 25 May

2020, “Indications on ventilation/air conditioning

systems in non-sanitary community facilities and

in domestic environments in relation to the spre-

ad of SARS-CoV-2 virus” reference to sanitization

as the sum of two phases, a thorough cleansing,

during which dirt and organic material are remo-

ved from the surfaces, followed by an effective

disinfection. There are several publications regar-

ding the products to be used for cleaning and disin-

fection operations, and over time they have become

increasingly specific. We just mention one of the

most recent, the ISS Covid-19 Report No. 19 dated

April 25, 2020:

“The ECDC (European Center for Disease Preven-

tion and Control) guidelines reports that, in princi-

ple, cleaning with water and normal cleaners and

disinfection with common disinfectant products is

per sé sufficient, as a first intervention, for the de-

contamination of surfaces even if no specific evi-

dence of their effectiveness on SARS-CoV-2 is still

available.”

There is also a regulatory reference, UNI EN 15780

“Ventilation of buildings - Pipelines - Cleaning of

ventilation systems”, which describes the ways to

evaluate and clean the ventilation systems of bu-

ildings. Therefore, it emerges once again that the

operations, in strict order, of cleaning and disin-

fection are indissoluble.

Bacteria

Bacteria are unicellular microorganisms that, ba-

sed on the shape they have, take different names.

Their classification is wide: they are divided both

according to their ability to survive with or without

oxygen and depending on the physical-pathologi-

cal aspect. To study them it is necessary to set up

a growth medium that allows to evaluate growth,

number, speed and motility, but not only. The infor-

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);

staphylococci (cocci arranged in clusters); strepto-

cocci (cocci arranged in chains); streptobacilli (ba-

cilli arranged in chains)

•

vibrions, comma shape

•

Spirilli, spiral shape

•

spirochete, corkscrew

Bacteria also divide according to their possibility to

live or not in the presence of oxygen. They are:

•

aerobic: they breathe oxygen and live in an envi-

ronment where oxygen is present. They grow only

in the presence of O2.

•

anaerobic: they live in oxygen-free environmen-

ts, and die if they are placed in an environment with

oxygen. They are, for example, intestinal bacteria.

•

other anaerobes: they live and grow even in the

absence of O2, but their growth is faster in the pre-

sence of 02.

Bacteria and health risks

One of the most dangerous bacteria we can find in

the environments intended for human use, is Le-

gionella. Legionella is a microorganism commonly

found in nature, where it is mainly associated with

the presence of water, whether it be rivers, lakes,

reservoirs, thermal springs or human use when it

flows out of our taps. Today, the infections caused

by Legionella are a serious problem and concern

due to the ever-increasing presence of the bacteria

in the hot water of our homes, hotels, campsites,

swimming pools, hospitals, nursing homes, and in

any situation where the water temperature is at le-

ast 25°C. It certainly does not help the return of

centralized systems and large volumes of accumu-

lation of domestic hot water, due in some cases to

the presence of solar systems, thus putting in di-

scussion the safety also in the residential sector,

where Legionella risk is increasingly high. But not

only ... High and dangerous concentrations can be

detected even in air conditioning units made up of

cooling towers, evaporative coolers or air humidi-

fiers. We are often faced with this problem in exi-

sting systems where there are already many issues

such as corrosion, limescale, dead circuit branches

in which there is no continuous water circulation,

and accumulations are not regularly monitored, all

these are aspects that favour the growth of Legio-

nella itself.

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