The Regulation and Importance of Indoor Air Quality Control

Categories: Air Pollution

The summer has hit once again along with extremities of weather. Hot and humid weather forces office buildings or any other workplace to crank up the air conditioner. Everything should be just fine as long as the heating ventilation air conditioning (HVAC) system has taken care of the indoor environment to be a comfortable setting.   

In past years, energy conservation and costs have taken its toll on human health due to poor indoor air quality.

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For seasons such as winter and summer when the weather outside is extremely hot or cold, HVAC systems recirculate the air existing in the building and potentially threaten the health of the occupants.

Air is recycled because of the costs to introduce fresh air. It would costs the owners of the building more to heat or cool the fresh air. Recirculated air is cheaper and much more efficient, but there is a potential price to pay.  

Other key factors in the demise of air quality are poor maintenance of existing HVAC systems and the layout or age of the building.

Combined with recirculated air and inadequate maintenance and layout, indoor air quality have been possibly lethal in extreme cases.  

This is by no means a new issue. It is a problem that has plagued indoor air quality since the time of dwellings. (Air & Waste Management Association, 2001) The problem has escalated though as of present due to technology and the population of mankind. Several instruments that have been intended to provide us with comfort, have contributed to the degrading of indoor air quality. Such instruments as air conditioners and humidifiers are a part of these contributors. So how does this technology affect the well being of the indoor air that we breathe? 

Government agencies across Canada have been receiving calls from people who are concerned about the quality of air in their workplace. These people want to know the causes of the various physical symptoms they are experiencing. (Health Canada – 1, 1995) One of the causes of the symptoms they are experiencing is the effects of biological factors in their work environment. Poorly engineered HVAC systems, poorly maintained buildings, incompetent maintenance personnel and equipment, inadequate circulation and ventilation, and over crowding in workplaces have enabled biological growth to flourish and cause illnesses and diseases. Biological factors that cause these detrimental effects are viruses, bacteria and fungi (moulds and yeast). Ultimately these microbes are present due to human activity. To elucidate how human activity or lack of compels pathogenic microbes to subsist, examples of situations will allow the comprehension of the existing problems with indoor air quality. 

Good heating ventilation and air conditioning (HVAC) systems are designed to provide thermal comfort (temperature and humidity control), distribute outdoor air to occupants, and remove odours and contaminants. (Health Canada – 1, 2001) However, indoor air problems may result when these systems are not maintained and improperly used. To search more in depth as to why biological factors co-exist with man-made machines is to investigate the components of are technological advancements.  

Some HVAC systems use cooling towers as a part of massive air conditioning system. The towers are based on a heat exchange system that discharges heat in to the atmosphere utilizing water evaporation. The net product is cooled air that is blown throughout a buildings ventilation system. Water used in the system is constantly recycled through the tower. This can pose a threat if bacteria flourishes in this recycled water. The water is usually capable of sustaining bacterial growth. Bacteria such as legionella have been one of the bacterium that has been most widely associated with causing illness due to this system. 

 Legionella is a pathogenic microorganism that readily survives and flourishes in water that has mild temperatures and the presence of algae and limescale. The warm recycled water circulated in water towers lends itself to a breeding ground for legionella. When mist from the contaminated recycled water escapes from the tower, legionella has the potential to be aerosolized and cause disease. If the water is constantly recycled and the tower is not cleaned or sanitized, this is the result. This is the way that the organism was first discovered in Philadelphia 1976, when 29 people perished when contracting the microbe at an American Legion Conference hence the name “Legionnaires’ Disease” or legionellosis.  The ventilation system spread aerosolized legionellae that the attendants inhaled throughout the conference.   

To cause legionellosis, the droplets must small enough to be inhaled into the lungs. Drinking contaminated water, as opposed to breathing in contaminated aerosols, has not been associated with Legionnaires’ disease. However, this possibility should not be entirely excluded. (Canadian Centre Foe Occupational Health & Safety, 1998) To further note on Legionnaires’ disease, it can lead to pneumonia a condition which the alveoli of the lungs becomes filled with fluid or pus and the victim can suffocate. When Legionnaires’ disease advances to the stage of pneumonia, there is a 5-15% chance of fatality. (Canadian Centre for Occupational Health & Safety – 1, 1998)  

Similar HVAC systems and other systems reminiscent to the system used in Philadelphia are used universally. They are in the workplace, hospitals, the homes and so on and they all have the opportunity to sustain the growth of bacteria like legionella. The most recent and serious case of a legionella outbreak that was spread via a water tower and the ventilation system was in Melbourne, Australia. There were 7 cases and 2 deaths. The 7 comprised of four patients, one construction worker (at an adjacent site), and two hospital staff. The two deaths were of the patient who was immuno-comprised. (HC Info, 2001) Unfortunately Canada does not keep records of the number of cases of legionella, but using American statistics as a basis, we can assume that there are about 2,000 infections a year with about 10% that lead to serious cases of pneumonia. (MediResource, 2000) Bear in mind though that there are other manners in which Legionnaires’ can be transmitted. 

Another source of stagnant water that can maintain the growth of legionellae are humidifiers. Comparable to water towers releasing tiny droplets into the air that can be inhaled, portable and humidifiers that are a part of HVAC systems will have the same effect. They add moisture to the air when there is low humidity. Unlike water towers, humidifiers are most prevalently used during the winter when the air is dry. Therefore legionella poses a threat in the winter and summer.  

The layout of the building can intensify the concentration of contaminated air in certain areas. Sealed off areas or physical barriers that restrict the airflow will have a greater concentration of pollutants. This is vital risk especially with legionella because of its low pathogenicity. It requires large amounts of bacterium to infect an individual. Having proper ventilation will ensure that there is a low concentration of pollutants in a given area. A proper ventilation system contains vents that are directed out of the building. Buildings that recycle air due to outside weather should ensure that their filtration systems is well maintained and the vent filters are changed regularly.

Some workplaces offer showers for their workers who want to use them at the end of the day after working in dirty conditions. The problem is that hot water tanks can also support legionella. If the hot water is not maintained at a high enough temperature, the bacteria flourish. The showers will emit aerosolized legionellae just like the water towers and ventilation system.  

To ensure that the water tank does not become infested with the bacteria, heat the tank above 600C as legionellae are susceptible to pasteurization at this temperature.  

Humidifiers, hot water tanks and cooling towers are all systems requiring regular maintenance. Keep in mind, that tanks containing water can be infected and that the contaminated water can be exposed to occupants. All water containers should be cleaned and sanitized on a regular bases using a specific biocide. The employer shall ensure this action.  

The only positive note pertaining to legionellosis is that, there have been no recorded cases of transmission person-to-person. Theoretically speaking, if the microbe was spread from person-to-person when the workers leave the contaminated site and then home, the whole family could be infected. From the home it could be spread elsewhere, but it fortunately remains at the source. It is not contagious.  

In the event of suspecting legionellosis, look for symptoms including headache, pain in the muscles, high fever, vomiting, diarrhea, chest pain and difficulty breathing. These will be a good indicator of Legionnaires’ disease. The severity of the disease can be intensified or more readily contracted if the individual smokes, excessively drinks, has diabetes or cancer, uses corticosteroid or is immunocomprised. Individuals with these attributes should be more precautious of water sources that they are exposed to and ensure that maintenance has been performed. For example, ask the employer if tests have been done and ask for their regular maintenance records. It is your right to know.

If there are any workers suffering from the above symptoms or a physician has confirmed the workers in the workplace have legionellosis, immediately close down the building for inspection and shut down all air circulation systems. Contact the Ministry of Labor or local health unit to have an inspector come in to take water samples from existing water sources in the building. The inspectors will take the samples to a lab for processing and tested for the possible contaminant. Employers and building owners should not ignore the problem. They shall immediately respond to the situation. If they have ignored to contact authorities and action is not taken, the health and lives of workers are at stake. Health officials will aid in tracking down the source of contamination and recommend procedures to eliminate the crisis.  

 Public health units can be contacted if patrons at a food premise have acquired these symptoms. PH inspectors will immediately interview victims of an outbreak to find the site of exposure and the cause of the illness. If they have pinpointed the source, for example The X restaurant, the establishment will be shut down until the source at the site has been found and the infestation has been eliminated. Point sources reminiscent to those of other workplaces will be investigated and tested.  

Viruses can also become a problem especially when there is overcrowding in the workplace. Unlike bacterium, viruses do not survive long outside of their infected host. Viruses could not survive the pathway such as legionella. They could not subsist in water or travel through air vents. What they can do is transmit from person-to-person when they are in close proximity. The contagious “common cold” is an example of how a virus spreads in this manner.

Bacteria and viruses are not the only microbes to be a nuisance in the workplace as of late. Moulds have presently agitated the workforce. In New Market earlier this year, the Courthouse was evacuated due to a mould infestation. Working became unbearable inside of the Court House.  

The Ministry of Labour issued an “Alert” in December 2000 due to skyrocketed complaints. According to Evelyn Stefov a MOL official, there were only 25 formal complaints lodged with the ministry in 1998-99. That number doubled to 52 in the following year and has risen to 106 in 2000-01. The number of work refusals has jumped from two in 1998-99 to 10 today. (Sahai, 2001)

Sufferers exposed to mould have complained about physical symptoms such as fatigue, shortness of breath, difficulty concentrating, sinus congestion, cough, sneezing, skin irritation, dizziness, headaches, nausea, and eye, nose, and throat irritation. These symptoms are intensified and more susceptible to individuals who have allergies, bronchitis, asthma, are young or elderly, and immunocomprised. Symptoms are caused by “mycotoxins” and spores, which the mould produces. Mycotoxins are metabolites or by-products from moulds that have been identified as being toxic to humans. (Canadian Centre for Occupational Health and Safety – 2, 2001) Allergy sufferers will have the most severe reactions to spores. They have allergic reactions called hypersensitivity pneumonitits.  Fortunately, once the exposure to any individual is halted the symptoms disappear. There are no chronic illnesses associated with mould but allergies towards mould may develop. Note that presence of mould does not always mean that health problems will occur. (Sahai, 2001) Some types of moulds are harmless. 

Whether you are at the office or construction site, there is the possibility of exposure to mould. Where there is moisture, mould can survive and flourish. Buildings with moisture problems can expect the presence of mould. The microbe in spore form can easily travel via airborne route and infest moist areas. Buildings that have a history of flooding, water leaks, sealed in areas with excess moisture, poor humidity control, or fires (water used to extinguish) have the highest risk of encountering mould problems. Other areas of concern are kitchens, HVAC systems and bathing facilities. Mould can form colonies on many different types of materials including tiles, drywall, wood, drapery, carpet, upholstery, ceiling tiles, soil, fabric, wallpaper and cardboard. A majority of building or worksites contain most of these materials. 

There are two methods to make an educated guess on the presence of mould. Firstly, colonies of mould can be visually seen. When inspecting, look for dark patches in moist areas. When working as an inspector (either health or labour), they will search for this presence on inspections. Health inspectors will usually give a food premise a few days to clean these patches of mould colonies and then re-inspect to see if they have complied. A fine will be submitted too the operator if they do not comply. A closure is unlikely unless the premised is severely infested. The other method of detecting mould is the smell. When there is considerable growth, the colony produces an odour.  

If mould has established itself and has caused a nuisance in the health of workers, it has to be controlled and eliminated. The first step to take would be to control the source of moisture. For example, fix leaky pipes or roofs. If the humidity has contributed to a source of moisture, control the relative humidity so it does not exceed 50%. Also have a good ventilation system in places where evaporated water is produced.  

After controlling the source of moisture concentrate on the materials where the colonies have formed.  Some materials will have to be disposed because it does not lend itself to cleaning. Once drywall or ceiling tiles have been water logged and there is presence of mould, it will have to be removed. Workers who are disposing of these materials shall wear personal protective equipment including body suits, eye goggles and a high-effeciency particulate air filter (HEPA) respirators. The concentration of airborne spores and mycotoxin will dramatically increase once the colonies have been disturbed putting the worker at a greater risk of exposure. A different approach can be taken for non-porous (smooth surfaces) materials that can be cleaned. Using a HEPA respirator, gloves and a sanitizing solution of one part bleach, 4 parts water and a small amount of non-ammonia based dishwashing detergent to cut surface dirt, simply clean the area with the solution. Never mix chlorine bleach and ammonia! (Canadian Centre for Occupational Health & Safety – 2, 2001) Good ventilation when working with bleach is always a must. Both methods of removal should first initiate with spraying a mist of water over the infected areas to keep the aerosolized mould down. Ascertain that sources of moisture are constantly in check; they can repopulate areas once there is water present. Mould spores can be present in the air for months even after the water source and colonies have been eliminated.  

There are legal requirements under the Health Protection & Promotion Act (HPPA) and the Occupational Health & Safety (OHS) Act that requires employers and operators to keep their premises and workplaces free from microbes such as pathogenic bacteria and mould. These premises are a great concern for inspectors because of their size. As opposed to an isolated case in the home setting (not to down-size the situation), there are more individuals at risk.  

Under the HPPA (a health inspectors jurisdiction), the maintenance of the building has been described. In section 11(a)(i) & (ii), every food premise shall be operated and maintained such that, the premises are free from every condition that may be a health hazard or adversely affect the sanitary operation of the premise. During inspection, inspectors will look for mould patches according to this section of the act. The colonies can affect the workers and patrons of the establishment. They will order that they are cleaned up and sanitized. Advice will be given to the operators to further prevent the recontamination of mould. Inspectors may also want to take a water sample from HVAC systems and hot water storage tanks to search for bacterium such as legionella to ensure that an out break does not occur. Operators will have to comply with the inspector’s wishes of testing and inspecting. If food operators do have an outbreak of legionellosis or patrons have suffered from symptoms that relate to legionella and they have contacted a physician to receive treatment, the health unit is the first resource that should be contacted to deal with the situation and ensure that no one else contracts the disease.  

When there has been an outbreak of Legionnaires’ disease, a health inspector will initially shut down the establishment to protect a high-risk population. This is due to the legionellas history of fatal cases. The inspector will search for sources of air contamination since legionella has to be inhaled to cause disease. Knowing if the employees and/or patrons have legionellosis will help in the investigation. I.e. A separate HVAC system may be utilized in a dining room and not the kitchen. Samples will be taken from aqueous sources and sent to the lab for immediate testing and processing. The samples will have to be properly labeled with the date, name, time and location of sample. Be specific. Once the source has been detected, a clean up will be ordered and legal action or a fine might be placed on the operator. Only when the site of bacterial growth has been found and cleaned may the food premise be reopened.

Inspections and reports of outbreaks and infestations in the labor jurisdiction are treated in a very similar fashion as public health. The difference is that the OHS Act covers the workers of a work place and not the public. Employers are required by section 25(2)(h) of the OHS Act to take every precaution reasonable in the circumstances for the protection of workers. The Act also places a responsibility on constructors (section 23) and supervisors (section 25) to ensure health and safety of workers. This includes protection from mould and bacterial infections. (Ministry of Labour – 2, 2000)  

All situations shall be dealt with in a prompt manner. The longer a crisis is prolonged; more people’s health will be at risk and the employer, owner or operator can be held liable for not taking immediate action. Legal action can almost be guaranteed if there are irresponsible acts associated with the matter.

Employers or operators should want to take the initiative to take control of these dilemmas. If the health or lives of his/her workers and/or patrons are at risk and action is not taken, there will be a negative image associated with them. Employees will be lost; business lost, responsibility with death, trouble with legal matters. There are no positive associations with solving the problem later. Deal with the problem then and there. Before the problem ever exists, schedule regular maintenance and testing. 

The survival of human life is dependant on the air we breathe. People spend about 80 – 90% of their time indoors. (City Green, 2001) The quality of air indoors is a great concern because of the time we spend inside. Inspectors of miscellaneous jurisdictions should be aware of the consequences of poor air quality. Like G.I. Joe says, “knowing is half the battle”.  

With a conscientious effort and responsible maintenance program, most past tragedies could have been prevented. The phrase, “those that don’t know history are doomed to repeat it” applies only to the ignorant. With the educated and skilled workforce that Canada has, outbreaks such as Walkerton should never occur, as they are quite controllable.  


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  2.  Health Canada – 2. (1995). Indoor air quality in office buildings: a technical guide. Canada. Minister of National Health and Welfare. 
  3.  Canadian Centre for Occupational Health and Safety. (1998). Legionnaires’ disease. [On-line]. Available: 
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  5.  HC Info. (2001). Recent outbreaks of Legionnaires’ disease. [On-line]. Available: 
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  8.  Ministry of Labour –1. (2000). Occupational Health and Safety Act. Toronto, Ontario. Queen’s Printers for Ontario. 
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The Regulation and Importance of Indoor Air Quality Control. (2021, Oct 31). Retrieved from

The Regulation and Importance of Indoor Air Quality Control
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