Usage Practices and Proper Maintenance of Home Air Conditioners and Their Relationship to Symptoms of Sick Building Syndrome Among a Sample of Housing Units and Their Occupants in Alexandria City

       The concept of air conditioning was known in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by Willis Havilland Carrier¹, and it was confined to winter comfort; that is, to heating the home to a comfortable temperature in the winter by means of open fireplaces or stoves. Later, improvements were made in the heating equipment by the introduction of steam and hot water heating.⁴

     Today air conditioning (AC) systems are found in the world because predicted increases in cooling high heat throughout the world running everywhere in the hot countries to get some relief from the heat: at work, at home, in the hotel, hospital, clinic, commercial centers, malls, airport, aircraft, vehicle and metro. Continued modernization of building stock, increased income, and a desire to reduce moisture in building materials continue to drive a sustained increase in air conditioner occurrence and use in the developed and industrializing world.²

With the continuous raising of the standard of living, the air conditioning of buildings has become a necessity in many cases to ensure that their living conditions meet the comfort requirements of its occupants, which results in greater satisfaction.³

Air conditioners transfer heat from indoor to outdoor through a compression-expansion cycle involving a refrigerant or working fluid. This heat moves against the spontaneous heat flow direction (warm to cold). The refrigerant must be heated up by compressing it through an electric compressor to a temperature higher than the medium into which the heat is transferred, so that it can release heat to the energy carrier medium through a condenser. The refrigerant must be cooled through an expansion valve to a temperature lower than the interior temperature, so that it can absorb heat from the internal through an evaporator. Then the refrigerant vapor is routed back into the compressor.⁵

There is a great variety of designs and equipment for air conditioning, which, together with the fact that several systems share common characteristics³.High voltage air conditioning (HVAC) systems are more used in different types of buildings such as industrial, commercial, residential, and institutional buildings. The main mission of HVAC system is to satisfy the thermal comfort of occupants by adjusting and changing the outdoor air conditions to the desired conditions of occupied buildings. Depending on outdoor conditions, the outdoor air is drawn into the buildings and heated or cooled before it is distributed into the occupied spaces, then it is exhausted to the ambient air or reused in the system. HVAC systems are all designed for the same purpose – to regulate the temperature of a building – but they’re not all designed in the same way. There are several popular types of air conditioning systems, and each has its advantages and disadvantages. Different systems use different energy sources, while some offer more compact designs over others. The most common systems are first, Window Air Conditioner (AC). It is a very common choice for controlling the temperature in a small room. It contains different components such as compressors, condensers, coils, and the evaporator, all in one single unit. Window AC is designed to fit into the window of a room, so it generally does not need any significant home modifications to be installed. Wall units are very similar to window AC, except they need a hole made in the room’s wall for them to be installed. Second Split or Multi Head Split Air Conditioners. These ductless systems are quite common in modern homes. They are referred to as split systems because they consist of two units, one kept inside your home and one outside. They can be used to cool or heat single areas, or multi-zone systems can be installed. These have one compressor outside, with several indoor units conditioning the air in various parts of your home. Third, Ducted Air Conditioning or central air conditioning can be the most efficient in many situations. A ducted system needs a large compressor on the outside of the building, an internal evaporative unit and ducts that bring conditioned air to the inside rooms through vents. Central AC system requires some significant modifications to your home and tends to have a high installation cost.⁶

ir conditioning is considered a double-edged sword, as it has many defects, including excessive consumption of electrical energy. Air conditioning has more harm to health such as it doesn’t pump fresh air from outside, but it recirculates the same air. It removes negative ions and increases positive ions which increases the acidity causing inflammation in our bodies which is the main reason of most diseases. Air conditioning systems can lead to many health problems such as respiratory problems, wheeze, shortness of breath, cough, asthma, Ear Nose Throat (ENT) problems, flu, rhinitis, pharyngitis, sinusitis, sore throat, loss of voice, dry mouth, allergies, eyes dry and irritated, skin disorders, wrinkles, acne, aging Raynaud’s disease, shoulder/knee/foot pain, as well as sleep disorders. negative effect on the absorption of nutrients as well as the elimination of waste material, constipation, gastroenteritis, high blood pressure, dehydration, migraine, nausea, heart palpitations, hot flashes with sweating or chills, tremor, dizziness, stress, anxiety, depression, chronic fatigue, and premature Menopause.⁷

Sick building syndrome (SBS) is one of the negative effects of air conditioning. World Health Organization (WHO) defined SBS as a group of non-specific symptoms occur to occupants which include eye, nose, and throat irritation, mental fatigue, headache, nausea, dizziness, and skin irritation, which appear to be related to certain workplace (WHO 1986 in ¹⁰). Occupants experience acute health problems and discomfort which appear to be linked to time spent in the building, where no specific illness or causes can be identified.⁸ The main source of SBS among several sources is ventilation which is influenced by the type of ventilation system. SBS is higher in buildings with mechanical ventilation system compared to natural ventilation.⁹

In addition to many problems resulting from the negative effects of air conditioning on operational efficiency and human health in buildings. Microbial biofilms on narrowly spaced heat-exchange surfaces impede airflow and heat transfer, thus increasing the energy required for cooling and dehumidifying. Aided by high air velocity over the coils, emissions from biofilms—including whole cells, microbial fragments, and microbial volatile organic compounds (MVOCs)—could be delivered to occupants throughout the building. While the mechanisms are largely uncharacterized, the presence of air conditioning and microbial growth on cooling coils has been linked to adverse health among building occupants.¹¹

The previous introduction makes it clear that as AC has some advantages, it has several disadvantages. The main purpose of this research was to determine the relationship between usage practices and proper maintenance of home air conditioners and their relationship to symptoms of sick building syndrome among a sample of housing units and their occupants in Alexandria city.

II.MATERIALS AND METHODS:

The study consisted of two parts, the first part was field study, and the second part was laboratory study.

Part one: Field study (survey):

objectives of this part were to study:

(a) Socio- economic characteristics of occupants.

(b) Housing characteristics.

(c) Usage practices, proper maintenance and problems resulting from home AC.

(d) Symptoms of sick building syndrome among the sample, they include respiratory system, neurological symptoms, orthopedic symptoms, and allergy which all result from AC.

(e) Testing hypotheses.

Research variables:

The research variables were represented in three types of variables:

1-Independent variables, which were represented in the socio-economic characteristics: marital status, number of family members, number of children, age, education and job of the husband and the wife, and family income. Housing characteristics include owning the home, floor number, number of rooms, number of AC.

2-Intermediate variables, they include: usage practices, proper maintenance, and problems resulting from home AC.

3-Dependent variables: symptoms of Sick building Syndrome among the occupants including respiratory system, neurological symptoms, orthopedic symptoms, and allergy.

Research hypotheses:

The study hypotheses were stated in the null hypotheses form as follows:

1-There is no significant correlation between each of socio-economic characteristics and housing characteristics of the occupants and each of usage practices, proper maintenance, and problems resulting from home AC.

2-There is no significant correlation between each of socio-economic characteristics and housing characteristics of the occupants and symptoms of sick building syndrome among the sample including respiratory symptoms, neurological symptoms, orthopedic symptom, and allergy.

3-There is no significant correlation between each of usage practices, proper maintenance, and problems resulting from home AC and symptoms of sick building syndrome among the sample including respiratory system, neurological symptoms, orthopedic symptom, and allergy.

4-There are no significant differences between the averages of symptoms of sick building syndrome occurring among occupants and the average of usage practices of the occupants.

Data collection: 

     The study was carried out on a sample consisted of 60 housing units and their occupants who own air conditioner in Alexandria city, Egypt. A questionnaire was developed to collect data from the sample. The questionnaire was pretested before collecting data through personal interviewing.

Developing the questionnaire:

      A questionnaire was developed to collect data. It included:

1. Socio- economic characteristics of occupants, they included number of family members, number of children, age of husband and wife, family income. To process data several variables were set in categories using the mean ± standard deviation, table (1).
2. Housing characteristics included ownership of the home, floor number, number of rooms, number of air conditioners, table (2).
3. Usage practices, proper maintenance and problems resulting from home AC:
4. Usage included each of duration of using AC all over the year in addition to its/ their type and site in the housing unit, table (3, 4).
5. Proper maintenance included accumulation of dust in the filter was estimated table (7), number of cleaning the filter, who and how it was cleaned table (5,6). In addition to studying general problems resulting from home AC table (8). To process data items included in proper maintenance were given marks and set in categories using the mean ± standard deviation table (9).
6. Symptoms of sick building syndrome (SBS) among occupants, to study symptoms of SBS four main health items were included: respiratory system, neurological symptoms, orthopedic symptoms, and allergy. The study included frequency of occurrence among occupants. To process data marks were given to occurrence of symptoms and set in categories using the mean ± standard deviation table (10,11).

Statistical analysis:

Statistical analyses were performed using SPSS program (ver.25) to determine the percentages, frequency, arithmetic mean ±, standard deviation, Spearman, and Pearson’s simple correlation coefficient, and multiple regression analysis.

Part two: Laboratory study:

Objectives of this part were to study the bacteria and fungi content of each of:

 Dust accumulated on the AC filter:

Dust samples were obtained using non- woven fabric swatches (with dimension 15cm X 15 cm) from 30 AC in 30 housing units. The area of AC filter is 30 cm X 25 cm. All swatches have been sterilized before sampling.

 Air coming out directly from AC:

        Air samples were collected from 30 AC taken out from the housing units of the field study in order to study bacteria and fungi content of the air coming out from AC filter. Sampling has been performed during August and September 2021. All AC sampled units were Split AC type, which means the air conditioning system is made up of two separate units. The air-cooled condensing unit called the compressor unit is placed outside the air-conditioned area whereas the air-handling unit is inside the room where the AC is fixed.

      The sample of the air was obtained via exposing two petri dishes filled with nutrient media. Two different medias were used, for bacteria Nutrient Agar M001: is used as a general purpose medium for the cultivation of less fastidious microorganisms, can be enriched with blood or other biological fluids, and it can be used for the cultivation and enumeration of bacteria which are not particularly fastidious, Cultural characteristics observed after an incubation at 35-37°C for 18-48 hours , for fungi, PDA media Potato Dextrose Agar MH096: recommended for the cultivation of yeasts and molds from pharmaceutical products in accordance with the microbial limit testing by harmonized methodology of USP/EP/BP/JP/IP, and growth was observed at 20-25°C for 2-7 days. Isolation and initially identification of microorganisms were carried out in the Microbiology Laboratory, Agricultural Botany Department, Faculty of Agriculture Saba Basha, Alexandria University, Egypt. The 16SrRNA gene was amplified from the DNA extracted from the isolated bacterial strains using primers P0 and P6, which was used in previous studies.18 The PCR product was then sent to a sequencing company (Macrogen Inc., Seoul, Korea), and the sequences were searched in the GenBank to be identified and then accessed using numbers generated by GenBank. For the fungi, the ITS region was used to identify the fungal strains from each other using ITS1 and ITS4 primers. (20,21) All the products were sequenced and applied to identify by the NCBI blast tool, and all the strains deposited in the GenBank under different accession numbers.

III.RESULTS AND DISCUSSION

Part one: Field study (survey):

(a) Socio- economic characteristics of occupants.

   Results indicated that 70% of the sample were married, family size was 3-5 members among 78.3% and 66.6% had 2-3 children. Results showed that the age of 73.4% of husbands was 27- 68 years and 70% of the wives age was 34-60 years. Both husbands (53.3%) and wives (56.6%) had bachelor’s degrees. 40% and 51.6% of husbands and wives had governmental jobs respectively. The family income of the majority (76.6%) of the sample ranged from 12600- 3957 Egyptian pounds per month (table 1).

Table 1. Socio- economic characteristics of occupants        

b) Housing characteristics:

      Results indicated that the majority of the occupants (85%) rented their apartments, 46.7% of the sample lived on the first floor up to the fourth floor. Regarding the number of rooms, results indicated that 76.7% of the apartments consisted of 3-5 rooms and 48.3% had one AC and 41.7% had 2-3 AC (table 2).  

Table 2. Housing Characteristics

(C) Usage Practices and Proper Maintenance and problems resulting from home AC:

1- Usage practices of AC:

       Results indicated that in general occupants used AC during summer season in the master bedroom (46.7%), children’s bedroom (23.3%), living room (45%), dining room (5%), reception (31.7%), and office room (1.7%). Only 1.7% of the sample used AC during the day in the living room in the autumn season. Most of the sample (55%) used AC during the night.  Regarding the number of hours of usage, results showed that 16.7% and 6.7% of the sample used it in master bedroom and children’s bedrooms respectively during sleeping time only. Also 13.3% of the occupants used the AC all night in the living room (table 3).

Table 3. Usage Practices of Ac, N = 60

Research results showed (Table 4) that most of the sample used split-type air conditioning with an indoor unit fixed to the wall (68.3%), and 20% used window air-conditioning, while 11.7% used split air-conditioning with an indoor unit recessed in the ceiling. The percentage of the rooms that had an air conditioner opened on side street was 48.4%, and 28.3% of the rooms overlook on a main street.

A study showed that areas with a hot summer, the temperature in air-conditioned rooms is usually maintained around 25 C, this is a temperature that corresponds to the neutral region for the human body in a static environment and should therefore not cause any pathological problem. However, the use of air-conditioning often leads to an increase in the difference between indoor and outdoor temperatures. Such difference in the temperature intensifies the thermal stimulation of people who are subjected to the sudden change of temperature sensation when moving between indoors and outdoors. People who remain in air-conditioned environment for a long period of time will suffer from heat shock and heat stress when they leave the cool environment of airconditioned rooms¹⁵.

Table 4. Type of air conditioning and views of the room that has air conditioning

2- proper maintenance and problems resulting from home AC:

       Maintenance was done once a year (46.7%) by a maintenance company (90%) for occupants who used AC during the summer season. For those who used AC in autem season, only (10%) maintain it every 3 months by maintenance company (23.3%). Regarding using AC to warm the home/ unit in winter maintenance was done every three months (8.3%) and every four months (6.7%) by a maintenance company (21.7%). During spring season 8.3% of the sample maintain the AC every 3 months by a maintenance company (18.3%), (table 5). Occupants who maintain their AC by themselves, results showed that one third (33.4%) washed the filter with water only, (table 6).   

Table.5 Proper maintenance and problems resulting from home AC

Table 6. Clean the air-conditioning filter

          Research studies showed that there is relation between the building dust and sick building syndrome, where it indicated an association between micro dust and diseases symptoms. Most of investigated buildings were naturally ventilated, poor cleaning, overcrowding, and poor space management. It was also found associations between the Gram-negative bacterial content of the dust and symptoms, as well as between the dust particulates and mucous membrane symptoms. Relations between volatile organics desorbed from the dust and general symptoms was found, as well as between the content of the dust and general symptoms. ^(13,14)

Air conditioning dust problems:

Research results presented in Table (7) indicated that the majority of the respondents suffered from the accumulation of dust on AC filter in summer in big quantity (40%), while 38.3% stated that dust accumulates on AC filter was in medium quantity in the autumn season, and 33.4% %, 38.3%, stated that the quantity of dust accumulated on air-conditioning filter in winter and spring seasons was in a small quantities respectively.

Table 7.  Air conditioning dust problems

Related problems resulted from AC usage:

Results indicated that 78.3% of the respondents suffered from high consumption of electricity while 20% stated that electricity consumption, noise, and health problems resulted from A.C. Results also showed that 8.3% suffered from unpleasant odors and had problems with neighbors (Table 8).

Table 8. Suffering from other problems caused by air conditioning

Data were classified into categories using the averages and standard deviation, (Table 9).

Table 9. Mean ± standard deviation and categories of variables under study

(d) Symptoms of Sick Building Syndrome (SBS) Among the Sample resulted from AC usage.

Previous studies showed that causes of SBS fall into three main reasons: allergic and immunologic disease, infections, and exposure to chemicals and other substances, SBS symptoms can affect skin, respiratory, and neurological systems. You may mistakenly self-diagnose yourself with a cold or flu.¹²

           Other studies added although objective physical abnormalities of SBS are not generally found except in a few specific diseases like Legionnaires' disease, the symptoms can be uncomfortable and even disabling. It is commonly accepted to represent eye, nose, and throat irritation; Neurotoxic symptoms like headaches, lethargy, difficulty concentrating, and sometimes have dizziness; nausea, chest tightness; and other symptom like Behavioral disorders chronic fatigue Genitourinary problems Learning disabilities, etc.¹⁶

1- Respiratory symptoms:

To identify health problems of the residents and SBS of the studied housing units under study, occupants were asked about some of the symptoms and diseases that they may complain of.

Results indicated that 23.3%, and 20% of the respondents suffered frequently from common cold and runny nose, respectively. Respondents who suffered from sneezing (41.6%), sore throat (38.3%), runny nose (30%), chest allergy (23.3%), and breathing problems (20%), stated that they fairly suffered (Table 10). The most common symptom was the sensation of a blocked or stuffy nose. True rhinitis with sneezing and running nose was much less common. The latter are the typical symptoms of allergic rhinitis due to an inhaled allergen. A feeling of dryness of the throat, perhaps associated.¹³

           2- Neurological symptoms:

                     Results showed that 10% and 13.3% of the sample respectively frequently felt fatigue. While 13.3% and 36.7% suffered from migraine sleeping disturbance fairly and rarely respectively (Table 10).

           3- Orthopedic symptoms:

                    Results indicated that 13.3% of the sample suffered from shoulder, knee, and neck pain frequently and osteitis. while 18.4% and 25% suffered from arthritis fairly and rarely respectively, (Table 10).

           4- Symptoms of allergy:

                          31.7%, and 26.6% of the sample suffered from sinusitis frequently or fairly respectively, also 13.3% suffered from ophthalmia fairly, 31.7% rarely suffered from skin allergy, and 36% did not suffer from watery eyes (Table 10).       Dry eyes are the least prevalent mucous membrane symptom, it can cause problems in those who wear contact lenses, who may not be able to use them throughout the day. Objective signs include reduced foam in the inner epicanthus and increases tear film break up time.¹³

Table 10. Symptoms of sick building syndrome resulted from AC usage

Table 11. Mean ± standard deviation and categories of variables under study

Data were classified into categories usage the averages and standard deviation, (Table 11).

(e): Statistical analysis (testing the hypotheses):

1-There is no significant correlation between each of socio-economic characteristics and housing characteristics of the occupants and each of usage practices, proper maintenance, and problems resulting from home AC.

          Statistical analysis showed that there was a positive significant correlation (0.01) between usage practices and number of the dwelling rooms. The correlation between proper maintenance and each wife’s and husband’s age was significantly negative (0.01), while there was positive significant correlation between proper maintenance, and number of dwelling rooms (0.01) (Table 12).

Spearman test values showed that there was negative significant correlation between proper maintenance, and marital status (0.05), positive correlation between related problems and each of husband’s job (0.05) and husband education (0.01), while there was negative significant between dwelling ownership and related problems (0.01) (Table 12).

Table 12. Values of the simple correlation coefficient and spearman test between some socio-economic characteristics & Residential characteristics and usage practices and proper maintenance, and problems resulting from home AC

                                      * 0.05                                                            ** 0.01               

2-There is no significant correlation between each of socio-economic characteristics and housing characteristics of the occupants and symptoms of sick building syndrome among the sample including respiratory symptoms, neurological symptoms, orthopedic symptom, and allergy.

Spearman test values showed that there was positive significant correlation (0.05) between each of neurological symptoms and overall health status, and room crowding, negative significant correlation between neurological symptoms, and wife’s job (0.05), negative correlation between Respiratory symptoms and dwelling ownership (0.01), negative correlation between Orthopedic symptoms and wife’s job (0.01) (Table 13).

Table 13. values of the simple correlation coefficient and spearman test between some socio economic & residential characteristics and Symptoms of SBS resulted from AC usage

                                      * 0.05                                                            ** 0.01               

3-There is no significant correlation between each of usage practices, proper maintenance, and problems resulting from home AC and symptoms of sick building syndrome among the sample including respiratory system, neurological symptoms, orthopedic symptom, and allergy.

Results showed that there was positive significant correlation (0.01) between health problems resulting from using AC, and each of respiratory symptoms, neurological symptoms, orthopedic symptoms, allergy, and overall health status (Table 14).

It was found that there was a negative significant correlation (0.05) between proper maintenance and neurological symptoms, (Table 14).

Table 14. The values of the simple correlation coefficient betweeneach of home air conditioning usage practices, proper maintenance, and Symptoms of SBS resulted from AC usage

                                      * 0.05                                                            ** 0.01               

4- There are no significant differences between the averages of symptoms of sick building syndrome occurring among occupants and the average of usage practices of the occupants.

One way analysis of variance showed significant differences (0.05) between the average of respiratory symptoms according to usage practices of AC, the healthy symptoms were among the fair usage category and the worst was among the bad usage categories. Results also indicated significant differences (0.01) between the average of orthopedic symptoms according to usage practices of AC, the healthy symptoms were among the fair usage category and the worst was among bad usage categories (Table 15).

Table 15. significant differences between averages of symptoms of SBS of occupants, and the average of usage practices of the occupants

                                      * 0.05                                                            ** 0.01               

Indoor environment is a crucial part of the design process; therefore, designers need to change their thinking about this physical environment and increase their awareness of health impact on occupants. Building factors that affect sick building syndrome are high indoor temperatures which enhances fungi, low fresh ventilation which enhances producing biological contaminants, poor individual control of temperatures, poor building service maintenance and poor cleaning or cleaning ability.¹⁷                                 

Part two: Laboratory study:

Many fungi, bacteria, molds, pollen, and viruses are types of biological contaminants cases, a malfunction of some component of heating, ventilation, and air conditioning (HVAC) system allows the organisms to grow and be disseminated.   Organisms can grow in spray-water air washers, air filters, poorly maintained cooling coils, and water leaking into air ducts humidifiers and drain pans, or where water has collected on ceiling tiles, carpeting, or insulation. Sometimes insects or bird droppings can be a source of biological contaminants. Physical symptoms related to biological contamination include cough, chest tightness, fever, chills, muscle aches, and allergic responses such as mucous membrane irritation and upper respiratory congestion. One indoor bacterium, Legionella, has caused both Legionnaire's Disease and Pontiac Fever.⁸

Data concerning isolated bacteria, fungi species and expected human diseases resulting from air condition usage in different places in Alexandria governorate, are presented in table 16 and 17. Results showed that bacteria isolated on the nutrient media were identified.

Identified bacteria were Bacillus sp., Rhodococcus sp., Corynebacterium sp., Micrococcus sp., Staphylococcus sp., Streptomyces sp., Micrococcus sp.

Identified fungi that were isolated on the PDA media, were Alternaria sp., Trichoderma sp., Fusarium sp., Cladosporium sp., Aspergillus sp., Mucor sp., Acremonium sp., Cladosporium sp., Penicillium sp., Epicoccum sp., Botrytis sp., Rhizopus sp., Phoma sp., Acremonium sp. It is obvious that the accumulated dust on the air conditioning filters contain significant numbers of bacterial and fungal species which could cause various human diseases. For instance, pneumonia, other respiratory tract irritation, asthmatic reactions to allergic inflammation. Respiratory health implications result from infection by Bacillus sp., Staphylococcus sp. and Micrococcus sp. bacterial species, respectively. ^(34,35,36)

        On the other hand, allergic diseases such as allergic rhinitis and asthma, respiratory inflammation, asthmatic diseases, breathing-related problems, skin allergies, constant sneezing, and red/watery eyes result from infection by Alternaria sp., Mucor sp. and Penicillium sp. fungal species, respectively. These results indicated that the accumulated dust in the air conditioning filters poses a threat for the buildings residents due to its microbial contents. ^(24,27,28)  

Table 16. Isolated bacterial species and the expected human diseases resulted from Air Condition usage in different places in Alexandria governorate, n=30

Table 17. Isolated fungal species and the expected human diseases resulted from Air Condition usage in different places in Alexandria governorate, n=30