How to protect yourself from Legionnaires’ disease when using an air conditioner

Recommendation points

• From heat to cold
• Air conditioning legionnaires disease
• Sick Building Syndrome
• At the end

In this article: how to choose the correct operating mode for a split system in the heat; disease of legionnaires and air conditioning systems; how to create and maintain a healthy atmosphere at home.

At the end of spring, with the onset of really warm weather, a wave of colds falls on the urban population, devastating offices of office and administrative buildings. The reasons for the general flight to sick leave are outwardly explained simply – after the winter cold and the cool off-season, the climate systems are switched to cooling the premises, which causes hypothermia of the office staff. However, the press from year to year names a different reason – a certain illness of legionnaires, the symptoms of which are similar to pneumonia in its severe form. Investigating the causes of summer colds and finding out how to avoid them.

From heat to cold

Every morning during the working week, office workers are sent through the crowd of city streets to their workplaces – to offices or halls, divided by 1.5-meter panels into sections designed for one or more employees. In their car, then at the entrance to the building, in the elevator car, in the corridor and at the workplace, people are faced with a constant flow of conditioned air and at first it is pleasant to feel it, because it is stuffy and hot outside. But the pleasant sensation of coolness will soon make itself felt with chills and a runny nose….

The first thing that the average office worker does after entering the office is to turn on the split system, setting the temperature to about 18 degrees and activating the turbo mode. The logic of this behavior: it’s hot outside, I’m sweating, I have to work at the computer, and at night the split was turned off – I will set the maximum modes, which will quickly cool the atmosphere of the room and get comfortable conditions in a short time. However, the human body refuses to follow the logic of reason and regards a sharp cold snap as a potential health hazard, activates the protection of vital organs from hypothermia and – a cold is guaranteed!

The difference between outdoor and room temperature in a room served by air conditioners, according to the calculations of medical workers, should not exceed 5 ° C at first. In other words, if you have just been in the heat of the street, and then got into a car or entered your personal account, then you should not immediately set the air conditioner to a low temperature regime – set the temperature at 25 ° C and only after 15 minutes you can set a lower one. temperature, if necessary.

For the human body, a comfortable temperature regime in a room with a normal humidity level (from 60 to 70%) is from +22 to +24 ° С, regardless of the season.

I note that intuitive attempts to achieve an optimal climate in the office by activating the split system at maximum cooling mode and partially opening the window sashes will not only force the air conditioner to work with overload, but will also cause a double draft – from the split and from the slightly open window, which will increase the chances of cold.

Attractive plastic screens offered by air conditioning equipment salons for office split systems, with the help of which you can change the direction of the flow of conditioned air and cut it off from workplaces located under the internal split unit, have a detrimental effect on the device. Because of the screen, some of the cold air it produces is pumped back into the hair dryer, causing the evaporator to freeze and increasing the compressor load to a critical level. If you want to avoid blowing out the workplace, then you should not purchase a cheap air conditioner – only models not lower than the middle price range and inverter ones produced under well-established brands..

Air conditioning legionnaires disease

The bacterium Legionella pneumophila attracted close attention of American physicians in the middle of the summer of 1976, after the 49th congress of members of the American Legion public organization, which included Americans who were veterans of various armed conflicts in the past. A little more than 2,000 members of the organization came to the next convention of legionnaires, held every year, in the city of Philadelphia (Pennsylvania, USA). To hold such a significant event, the organizers rented a banquet hall at the Bellevue-Stratford Hotel in Philadelphia, the building of which was equipped with a modern industrial air-conditioning system with water-cooled condenser (cooling tower).

The three-day congress was successful, the legionnaires went home, but two or three days later 130 veterans aged 39 to 82, mostly males, felt unwell – a disease that outwardly resembled pneumonia in symptoms developed unusually quickly. The patients became worse, the antibiotics, which were usually used to treat pneumonia, did not help them – 25 of the sick people died within a few days. The news of their death, picked up by the media, caused panic, the US government demanded that the “Center for Disease Control and Prevention” find out the cause of the disease and its source as soon as possible. Since all the patients attended the Congress of the American Legion, the search for the pathogen was carried out at the Bellevue-Stratford Hotel – the building was literally studied by centimeter, all internal communications were opened and studied for microbiological flora.

In early January 1977, the causative agent of Legionnaires’ disease was discovered – it turned out to be a poorly studied genus of bacteria that lived in the cooling tower of the hotel’s air conditioning system, in a tank containing water for cooling the condenser of the refrigeration circuit. The cistern, like all industrial air conditioner units, was located on the roof of the hotel, under the sun’s rays the water temperature in it reached 35 ° C, i.e. ideal conditions for the development of legionella bacteria were achieved. During the operation of the air conditioning system, legionella got into the ventilation ducts, then into the hall where the participants of the legionnaires’ congress gathered.

Outbreaks of Legionella pneumonia have occurred in the United States and Europe prior to the tragic events in the Philadelphia hotel, but there has been no thorough search for the causative agent. In the early 80s, scientists determined exactly how to treat pneumonia of legionnaires, today it does not pose a particular threat.

Can Legionella pneumophila live in domestic split systems? The development of a legionella colony requires water with a temperature of 25 to 45 ° C, contained in a container, i.e. not flowing. In any household air conditioner, there really is a container for collecting condensed water, but its temperature cannot exceed 5 ° C – a refrigerant that changes the physical state in the evaporator radiator from liquid to gaseous under the influence of air pumped in from the room cools the evaporator unit to about 0 ° C. Accordingly, the condensate formed on the fins of the evaporator also has a temperature close to zero, so the liquid entering the condensate storage tank cannot heat up. And since condensate is constantly removed from the indoor unit through the drain pipe, then a split system that is switched off for a long time will not create conditions for the development of legionella. The only possible option is a faulty condensate drain, for example, when the outlet pipe is clogged. Therefore, the operating state of the condensate drainage system must be carefully monitored and malfunctions must be eliminated in time..

Sick Building Syndrome

Any house, moreover, built using construction chemicals, over time, habitat various bacteria and mold microorganisms, street dust and pollen are deposited in its premises – all this can lead to respiratory and vision diseases in humans. Since about the mid-80s, due to the widespread use of air conditioning systems and airtight window frames, this situation has worsened, since the amount of fresh air entering the premises has sharply decreased – households have stopped ventilating rooms, relying on air conditioners.

In the internal rooms and halls of buildings, isolated from the external atmosphere, practically the same volume of air rotates, even if it passes through air conditioners of different capacities and equipped with a filter system, but without fresh air from the street! Dust, pollen, chemicals – all this is raised by split systems into the air again and again, because this, in addition to cooling or heating the air, is their job. Against the background of the owners of air conditioners ignoring the need for periodic cleaning of climatic devices, their internal blocks are clogged with dust, in conditions of constant humidity due to condensation of the unit housings in the splits, microorganisms inhabit, imparting a characteristic putrid smell to the air coming from the device.

To avoid the consequences of living in a modern, but hopelessly “sick” building, you need the following:

• regularly clean the premises using a modern and sufficiently powerful vacuum cleaner. During cleaning, the air conditioner must be turned off, otherwise some of the dust will remain in the room in a suspended state;
• minimize the area or completely abandon carpets and similar decor items;
• carefully monitor the frequency and carry out preventive work with climatic equipment, attracting real specialists for this, and not dubious shabashniki;
• maintain air exchange in the premises at a level not lower than eight-fold complete change of air volume every 24 hours;
• any finishing work inside the premises should be performed only with open windows and with the climatic devices turned off.

At the end

Any household and industrial appliances are capable of making a negative contribution to the atmosphere of the premises if they are operated in violation of the requirements set forth by the manufacturers in the instructions. Please note that attempts to save on maintenance of climate systems and their improper use will lead to much higher costs, only to restore health.

On this material, the cycle of articles on climatic equipment is completed. Guided by the information set out in a series of “climatic” articles, you can choose the climatic device you need, check the quality of installation work and monitor its technical condition during the entire period of using the air conditioner.