The impact of poor ventilation in the spread of airborne diseases

Introduction

Ventilation is the replacement of air in a surrounding by a supply of fresh outdoor air and the control of the quality of incoming air with regard to its temperature, humidity and purity with a view to providing a thermal environment that is conformable and free from risk of infection (i.e. to control temperature, replenish oxygen, or remove moisture odours smoke, heat, dust, airborne bacteria and carbon dioxide) it is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating and to prevent stagnation of the interior air (Porter, 2008).

According to Sangha (2012), poor ventilation can potentially become extremely hazardous for the health of humans. When combined with reasonable moisture levels (poor ventilation often leads to raised moisture levels), moulds can survive (thrive) and fungal spores can cause breathing problems.

Inadequate or poor ventilation is associated with a high risk of airborne infectious disease transmission, which includes tuberculosis, as well as the accumulation of indoor pollutants and dampness, which are factors in the development of allergies and asthma (World Health Organization, 2010).

Canada Communicable Disease Report (2007) stated that in a house, special factors to consider are the outdoor temperature, noise, comfort, energy lost, condition of windows or doors or cultural and personal habits and these tend to increase susceptibility to airborne diseases (Fennelly, 2004).

An airborne disease is any disease that is caused by pathogens and transmitted through the air. Such diseases include many that are of considerable importance both in human and veterinary medicine (Mitchell and King, 2004).

Types of ventilation

According to Russell and Hudson (2011), there are two major types of ventilation which are;

• Natural ventilation
• Mechanical (artificial) ventilation

Natural ventilation

Natural ventilation is the simplest system of ventilating a small dwellings, schools and offices. In this method, reliance is placed on certain forces which operate in nature. They are;

• The wind: The wind is an active force in ventilation. When it blows through a room, it is called perflation. When there is an obstruction, it bypasses the room it is called aspiration. Doors and windows facing each other provide “cross ventilation”.
• Diffusion: Air passes through the smallest openings or spaces by diffusion. This is a slow process and therefore is not relied upon as the sole means of ventilation.
• Inequality of temperature: Air flow from high density to low density; it rises when slightly heated and escapes from openings provided high up the room. The outside air which is cooler and denser will enter the room through inlets placed low. The greater the temperature difference between the outside and the inside air, the greater the velocity of incoming air.
• Mechanical (artificial) ventilation

Mechanical or artificial ventilation may be classified according to Rusell and Hudson (2011) into four different types, which are

• Exhaust ventilation
• Plenum ventilation
• Balanced ventilation
• Air conditioning

• Exhaust ventilation: In this system, air is extracted or exhausted to the outside by exhaust fans usually driven by electricity. As air is exhausted, a vacuum is created which induces fresh air to enter the room through windows, doors and other inlets. Exhausted ventilation is usually provided in large halls and auditoria for removal of air. The exhaust fans are housed in the external walls high up near the roof which facilitate removal of the upper layer of the heated air.
• Plenum: In this system, fresh air is blown into the room by fans so as to create a positive pressure and displace heat air. Plenum or propulsion system is used for supplying air to air-conditioned buildings and factories.
• Balanced ventilation: This is a combination of the exhaust and plenum systems of ventilation. The blowing fan must balance the exhaust fan.
• Air-conditioning: Air-conditioning is defined as the “simultaneous control of all or at least the first three of those factors affecting the physical and chemical conditions of the atmosphere within any structure. These factors include temperature, humidity, air movement, distribution, dust, bacteria, odour and toxic gases most of which affect in greater or lesser degree human health and comfort”. In air-conditioning, the air is first filtered and then saturated with water vapour. The excess of moisture is removed and the air is heated to the desired temperature before it is supplied.

Types of airborne diseases associated with poor ventilation

Many common infections can be spread by airborne transmission at least in some cases, including, Anthrax, Asthma, chicken pox, Influenza, measles, smallpox and tuberculosis.

Anthrax

Anthrax is an acute disease caused by the bacterium bacillus anthracic. Most forms of the disease are lethal and it affects both human and animals (Hudson, Daniel and Morgan, 2006).

Anthrax does not spread directly from one infected animal or person to another; it is spread by spores. These spores can be transported by clothing or shoes. The body of an animal that had active anthrax at the time of death can also be a source of anthrax spores which are inhaled or ingested.

Stern Bach (2002) stated that respiratory infection in humans present cold or flu-like symptoms for several days, followed by pneumonia and several respiratory collapse. While gastrointestinal infection is characterized by serious difficulty, vomiting of blood, severe diarrhoea and loss of appetite.

However early detection of sources of anthrax infections can allow preventive measures to be taken. Vaccines against anthrax for use in livestock and humans have had a prominent place in the history of medicine (Bohn, 2008).

Asthma

Asthma is a common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction and bronchi spasm (Maske and Busse, 2010). Common symptom includes wheezing, coughing chest tightness of breath.

Yawn (2008) stated that asthma is taught to be caused by a combination of genetic and environmental factors (such as allergens, air pollution and environmental chemical). It is chemically, classified according to the frequency of symptoms, forced expiratory volume in one second and peak expiratory flow rate and may also be atopic (extrinsic) or non atopic (intrinsic).

Treatment of acute symptoms is usually with an inhaled short-acting beta-2 aganise (such as sulbutamol) and oral cortico steroids (Miller and Ho, 2008).

Chicken pox

Chicken pox is a highly contagious disease caused by primary infection with varicella zoster vinis (V2V). It usually starts with a vescicular skin rash mainly on the body and head rather than on the limbs. The rash develops into itchy raw pock marks, which mostly heal without scarring (Wood, 2007).

Centre for Disease Control and Prevention (2002) stated that chicken pox is an airborne disease which spreads easily through coughing or sneezing by ill individuals or through direct contact with secretions from the rash. A person with chicken pox is infectious one to two days before the rash appears.

The signs and symptoms of chicken pox includes nausea, loss of appetite, aching muscles, headache followed by characteristic rash or oral sores, malaise and low-grade fever as well as spots in the oral cavity (Domino, 2007).

According to Brannon (2008), the spread of chicken pox can be prevented by isolating affected individuals and the chicken pox virus is susceptible to disinfectants like chlorine bleach (sodium hypochlorite). The varicella vaccine has been made available to inoculate against the disease as part of immunization.

Measles

Measles also known as morbilli or rubella (and not to be confused with rubella) is an infection of the respiratory system, immune system and skin caused by virus specifically paramyxo virus of the genus morbilli virus.

Symptoms usually develop 7-14 days (average 10-12) after exposure and they include high fever, kopliks spots, malaise, loss of appetite, hacking cough, running nose and red eyes (Caserta, 2013).

Perry and Halsey (2004) stated that measles is spread through respiration (contact with fluid from infected person’s nose and/or mouth either directly or through aerosol transmission) and is highly contagious. In developing countries, children are immunized against measles at 12 months, generally as part of three part MMR vaccine (measles mumps and rubella) as a means of preventing the disease.

Influenza

Influenza commonly known as the ‘’flu’’ is an infectious diseases of birds and mammals caused by RNA viruses of the family thomyxo virrdae, this influenza viruses A, B and C. The most common symptoms are chills, fever, running nose, sore throat muscle palms headache, coughing, weakness or fatigue and general discomfort and it may produce nausea and vomiting Particularly in children (Brankston 2007).

Jefferson (2011) opined that influenza is typically transmitted through the air by cough or sneezes, creating aerosols containing the virus but the virus can be inactivated by sunlight, disinfectants and detergents.

Grady (2009) stated that reasonably effective ways to reduce the transmission of influenza includes good personal health and hygiene habits, such as not touching your eyes, nose or mouth, frequent hand washing (with soap and water, or alcohol based hand rubs) covering coughs and sneezes, avoiding close contact with infected person, avoiding spitting and staying house alone when infected.

Tuberculosis

Tuberculosis MTB or TB (short for tubercle bacillus) is a widespread infectious disease and in many cases fatal, infectious disease cause by various strains of mycobacterium, usually mycobacterium tuberculosis. Tuberculosis typically attacks the lungs, but can also affect other parts of the body (Kuma, Abbas, Fausto and Mitchell, 2007).

According to Konstantions (2010), tuberculosis is spread through air when people who have an active TB infection cough, sneeze or otherwise transmit respiratory fluids through the air. The classic symptoms of active TB infection are chronic cough with blood. Fringed sputum, fever, high sweats and weight loss. It is also characterized by loss of appetite, fatigue and significant nail clubbing.

Tuberculosis prevention and control effort primarily rely on the vaccination of infants, detection and appropriate treatment of active cases. The only available vaccine is Bacillus Calmette Guerin (BCG) which decreases the risk of getting the infection in children (Kabra, 2006).

Mode of transmitting airborne diseases

An airborne disease can be caused by exposure to a source such as an infected patient or animal, by being transferred from the infected person or animal’s mouth, nose, cut or needle puncture. Another way is through the route of transmission contact air (droplet food or vector).

According to Mingle (2004), most airborne diseases tend to affect the respiratory system, causing congestion of the sinuses or lungs, some examples are coughing or sneezing, fever, sore throats and itchy eyes. The bacteria and virus responsible for these diseases are typically carried in saliva and mucus. When a person sneezes or coughs, they emit spray that can travel as far as 15 feet. The droplets in this spray or most are easily inhaled by others nearby, this transmitting the virus to them as well.

According to Chungtan (2007), airborne disease can be transmitted through mechanisms which are:

• ­­Droplet
• Droplet nuclei
• Dust borne particles

1. Droplet: These are fluid secretions from the mouth, nose or respiratory tract of an infected person usually released through coughing and sneezing.
2. Droplet nuclei: These are dried up droplet/secretions found in the air usefully containing nuclei of an infective agent.
3. Dust borne particles: These are fluid secretion of an infected person which has mixed with dust in the air.

Impact of poor ventilation in the spread of airborne diseases

Ventilation is said to be poor when it does not provide acceptable indoor air quality or does not allow proper exchange of air to the outside as well as circulation of air within a building (Porter, 2008).

According to Sangha (2012), poor ventilation can potentially become extremely hazardous for the health of humans. When combined with reasonable moisture levels (poor ventilation often leads to raised moisture levels) mould can thrive and their fungal stores can causes breathing problem

Inadequate or poor ventilation is associated with a higher risk or airborne infectious disease transmission, including tuberculosis, as well as the accumulation of indoor pollutant and dampers, which a factors in the development of allergies and asthma (World Health Organization, 2010).

Canada Communicable Disease Report (2007) showed that transmission of airborne bacteria to a non-infected person is more likely if there is poor ventilation. It added that occupancy density, room volume and air change rate are all directly correlated with the number of new infections among persons who share airspace. Air change occurs in a room when a quality of air equal to the volume of the room is supplied and /or exhausted. (Beggs, 2003).

Factors that may inhibit or increased ventilation in a house are the outdoor temperature, noise, comfort, energy, loss habits and these tend to increase susceptibility to airborne disease (Fenelly, 2004).

Crowding has been identifying as a risk factor for airborne disease transmission (Clark, 2002). He added that in communities where persons with TB disease live in crowded houses leads to an increased risk in terms of exposure to the causative organism. The risk of exposure is also increased if there is limited air movement in an enclosed space.

Mingle (2014) added that airborne illness are most commonly spread in enclosed area containing a large amount of people in close contact. This typically included places such as school, daycare centres, offices and   even hospitals. It is worse in buildings with unsanitary conditions or little to no ventilation. For these reasons many third world countries or stuffy buildings with poor air flow are areas of high risk for contracting airborne diseases.

General preventive and control measures for airborne diseases

According to World Health Organization (WHO, 2010), the following are necessary measures for preventing and controlling airborne disease in the society.

1. Proper and adequate ventilation of building and offices
2. Early detection of source of infection
3. Prompt immunization of children
4. Isolation and treatment of infected person
5. Proper and adequate personal health hygiene
6. Frequent hand washing with soap and water
7. Use of disinfectants like chronic bleach for laundry of for mites
8. Chemoprophylaxis that is use of drugs to control illness
9. Avoiding close contact with infected person
10. Covering of mouth during cough and sneezes

Possible ways of improving ventilation to control airborne diseases

Indoor air is often ten times more polluted than outdoor air. Indoor air pollutants contribute to asthma as well as other respiratory conditions and diseases (Environmental Protection Agency, 2010).

According to Means (2009), there are three general stages of improving ventilation which are:

• Source control
• Improved ventilation
• Air cleaning

1. Source control: This entails eliminating sources of pollution or reduces their emission. This is the most effective and should be the first step to take. Although, many source control options are easy and inexpensive.
2. Improved ventilation: This will improve ventilation quality by increasing the amount of outdoor air coming into your home, diluting concentration of indoor pollutants and pushing state indoor air out of the home.
3. Air cleaning: This involves the use of mechanical air cleaner to filter pollutants out of the indoor air and can be used to supplement source control and ventilation but it is not recommended as the sole solution.

Conclusion

The outcome of this seminar showed that airborne diseases are caused by pathogens and spread when droplets of pathogens are expelled into the air due to coughing sneezing or talking. Nevertheless, poor ventilation is known to be a major contributing factor to the spread of these diseases as it does not allow proper exchange of air thus contributing to air borne disease; thus contributing to airborne disease transmission which calls for public health concern.

Recommendations

In the light of the observation in this seminar work, it is recommended that;

1. All those infected with airborne diseases should be isolated
2. Close contact with infected person should be avoided
3. Proper and adequate personal and health hygiene should be practiced
4. Houses should be built following laid down standards
5. Proper and adequate ventilation should be ensured in buildings and offices
6. Individual should ensure covering of mouth during cough and sneezes

References

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