PhytoScience - Article

Air Quality - Biological Hazards

 

Often we do not think of air pollution as separate pollutants, but as the broader issues that these pollutants are a part of, including:

These issues are influenced by several factors including our land use patterns and behaviours, as well as the transboundary movement of air pollutants across long distances, such as from the United States.
Climate change and stratospheric ozone depletion are related issues of concern. Learn more about the relationship between these and clean air.  

Smog

Smog compromises the quality of our air. It can be seen as a yellow-brown haze along a city skyline or as a thick pollutant-rich fog enveloping our daily activities and natural landscapes. When the pollutants and conditions for producing smog come together in the right way (or perhaps the wrong way), the result can be quite severe, leading to many human health and environmental concerns.

Acid Precipitation (Acid Rain)

Acid precipitation, or acid rain, continues to be a major concern for our natural and built environments, especially in the eastern regions of Canada (i.e. the Windsor to Quebec City corridor). Its impacts can be as subtle as lowered vegetation growth and productivity, to as dramatic as significant losses in forest cover and aquatic life. Many of our limestone buildings and statues are particularly vulnerable to the effects of acid rain.

Indoor Air Pollution

Air pollution is not only an outdoor problem. The air indoors, at home and in your workplace can also be polluted, and in some cases be more polluted than outside. Many types of indoor air pollution exist, such as mould, smoke, and carbon monoxide. Indoor air quality is particularly important since, on average, Canadians spend most of their time indoors.

Land Use

The design of cities and our roadways, and the location of our places of work and home and other aspects of land use all influence how much we need our motor vehicles to get around. The concern is that this dependency secures or increases transportation's role as one of the major sources of air pollution.
At the same time, forests, prairies and other natural features are lost in order to make way for our roads, cities and industrial activities, which can reduce the ability of the environment to naturally filter out many air pollutants, or even maintain healthy populations.

Transboundary Movement of Air Pollutants

Air pollution does not respect political boundaries, whether provincial or national. Winds can transport pollutants long distances away from their source, adding to the levels of air pollution that are generated locally, and greatly increasing the intensity of our air quality concerns.

Recognizing the need for collaboration and partnership, Canada and the United States have entered into an agreement to monitor and mediate sources of transboundary air pollutants.

 

Indoor Air Quality - Moulds and Fungi

 

Why does mould grow in homes or buildings?


Moulds and fungi are found in nature and are necessary for the breakdown of leaves, wood and other plant debris. These micro-organisms can enter a building directly or by their spores being carried in by the air. In a home or building, moulds and fungi are usually found growing on wood, drywall (plaster/gypsum/Sheetrock(R)), upholstery, fabric, wallpaper, drapery, ceiling tiles, and carpeting.
The key factor is moisture because moulds and fungi need it to grow. As a result, moulds and fungi are most often found in basements, kitchens and bathrooms.
In modern buildings, moisture is present as the result of :

  • flooding,
  • leaks in the roof or plumbing,
  • sealed buildings that do not allow excess moisture to escape,
  • sources such as cooking facilities, showers, etc., or
  • excess humidity.

* In this document, the term mould will be used to mean any of mould (mold), mildew, yeasts, and fungi. 

What are some types of mould?


While it is interesting be able to identify what type of mould may be growing in the building, it is not necessary to identify the type(s) present. The Centers for Disease Control and Prevention (CDC) states that all moulds should be treated the same in terms of health risk and removal.
Some of the more common types of mould found in buildings include:

  • Stachybotrys chartarum (also known as Stachybotrys atra)
  • Aspergillus sp.
  • Penicillium sp.
  • Fusarium sp.
  • Trichoderma sp.
  • Memnoniella sp.
  • Cladosporum sp.
  • Alternaria sp.   

How do moulds contribute to health problems?


The presence of mould does not always means that health problems will occur. However, for some people the inhalation of the mould, fragments of the moulds, or spores can lead to health problems or make certain health conditions worse.
In addition, many of these moulds make "mycotoxins". Mycotoxins are metabolites or by-products from the moulds that have been identified as being toxic to humans. These toxins can slowly wear down the immune system and can lead to allergic or respiratory problems.
In general, the most commonly reported symptoms include:

  • runny nose or nasal congestion
  • eye irritation
  • cough or congestion
  • aggravation of asthma
  • fatigue
  • headaches, and
  • difficulty concentrating.

Moulds can also exacerbate (make worse) the symptoms of allergies including wheezing, chest tightness, shortness of breath as well as nasal congestion and eye irritation. People who are immuno-suppressed or recovering from surgery are usually more susceptible to health problems from moulds. 

What can I do to prevent mould contamination?


Moulds can grow almost everywhere and on any substance providing moisture is present. Thus, the best method of prevention is to reduce the amount of moisture.
Keep the relative humidity between 30% and 50%. To accomplish this goal, prevention measures include:

  • Vent showers and other moisture generating sources directly to the outside.
  • Control humidity with air conditioners and/or dehumidifiers*.
  • Use exhaust fans when cooking, dishwashing, or laundering (especially in the food service or laundry areas) or when cleaning large areas.
  • Insulate cold surfaces to prevent condensation on piping, windows, exterior walls, roofs and floors where possible.
  • Keep the building and the heating, ventilation and air conditioning (HVAC) systems in good repair.
  • Clean up any floods or spills immediately (within 24-48 hours). See below for more information on cleaning, etc.
  • For floors and carpets, remove spots or stains immediately. Reduce the amount of water used when cleaning carpets as much as possible.
  • Do not install carpet around fountains, sinks, bathtubs/showers or directly on top of concrete floors that are prone to leaks or frequent condensation.

* It is important to remember that when using air conditioners and dehumidifiers to keep them in good condition. Empty any water collectors regularly so this water does not contribute to the moisture problem! If you use humidifiers, ensure that they are cleaned regularly.

 What should I look for during an inspection?


A visual inspection is the most reliable method of identifying mould problems. The most common signs of water damage will be discoloration and staining. Moulds will most often appear as dark spots, stains or patches. If you find a suspicious spot, you can do a check to see if it is mould or fungi by dabbing the spot with a small amount of chlorine bleach. If the color changes or disappears, the stain is "likely organic and probably mould" (Canada Mortgage and Housing Corporation, 1999).
While conducting the inspection, be sure to look at, in, or under the following places:

  • ceiling tiles
  • walls including wallpaper, and condition of drywall (Sheetrock (R) [USG], gypsum wall board)
  • floors,
  • window sills
  • insulation,
  • carpet,
  • furniture (condition of fabric, upholstery, etc.),
  • if possible, look behind duct work and walls (a mirror will help)
  • condition of any cardboard or paper present

Also look for "standing water" - puddles of water around and under sinks, tubs, drip pans for dehumidifiers, air conditioners, and refrigerators that can be contributing to the moisture in the building and provide conditions where mould can grow.

Surface sampling can be done by scraping or swiping suspected spots if needed for medical evaluation but this should be done by a trained professional. Air monitoring is also possible, but it is not considered routine. (New York City Department of Health, 2000)
Monitoring devices are available which can measure the moisture level of drywall, wood, etc. These devices will help indicate whether or not moisture levels exists that would promote the growth of mould.

How should I clean up the mould?


In general, once mould has been discovered, it is recommended that porous materials such as dry wall, ceiling tiles, fabric or carpet be thrown out and replaced rather than cleaned whenever possible. Non-porous materials such as metal, glass, hard plastic and semi-porous materials such as wood and concrete can be cleaned and reused (if structurally sound).
How to clean the mould depends of the size or extent of the damage.

For small areas (less than 30 square feet):

  • Use a disposable respirator as well as glove and eye protection. A high-efficiency particulate air filter (HEPA) respirator will provide a higher level of protection.
  • It is not necessary to vacate the building, but persons who work close by or those who are immuno-suppressed, those with chronic lung problems (such as asthma, allergies, etc) or those recovering from surgery may wish to work in a different section or area on those days.
  • Dust suppression methods such as misting the surface lightly before cleaning is recommended.
  • Clean the area with water and detergent.
  • Area should be dry and free of any visible contamination when the work is completed.

For larger areas or areas of high contamination:
While large remediation projects should be done by trained professionals, some good work practices include:

  • Persons working in this situation have appropriate training in disposal and removal the biological contamination.
  • Wear a high-efficiency particulate air filter (HEPA) respirator plus appropriate glove and eye protection. Wear disposable protective clothes such as coveralls, head cover and shoes.
  • Isolate the area from the rest of the working space with plastic sheeting and by sealing ventilation ducts and other openings.
  • Use an exhaust fan with a HEPA filter to create a negative pressure in the space.
  • It is not necessary to vacate the building, but persons who work close by or those who are immuno-suppressed, those with chronic lung problems (such as asthma, allergies, etc.) or those recovering from surgery may wish to work in a different section or area on those days.
  • Discarded materials should be sealed in plastic bags for disposal. HEPA vacuum or wipe the sides of the bags before carrying outside of the sealed area.
  • The contained area, as well as the entrance to it, should be HEPA vacuumed and cleaned with a detergent solution.

If the contamination is in the Heating, Ventilation and Air Conditioning (HVAC) system:

  • Small amounts of contamination can be cleaned as above for small surface areas. Large scale contaminations should be handled by trained professionals.
  • The HVAC system should be turned off during cleaning.
  • All areas should be dried before the system is turned on again.
  • Biocide products are available for various HVAC components such as condensation pans and cooling coils. Check with the manufacture for specifications and for handling instructions.
  • The work area should be HEPA vacuumed and cleaned with a detergent solution.

Precautions:

  • The use of chemical disinfectants such as chlorine for remedial purposes is not recommended.
  • The use of chemical disinfectants can pose health concerns for people in occupied spaces of the building.
  • Vacuuming may increase exposure to mould and spores by making them airborne. Central vacuums that exhaust to the outside, or those equipped with high-efficiency particulate air filters (HEPA) will minimize this exposure.
  • No special requirements are necessary for the disposal of moldy materials although it is recommended that the materials be sealed in plastic bags if possible.


For a more detailed report on various remediation projects, please see the following*:
The New York City Department of Health "Guidelines on Assessment and Remediation of Fungi in Indoor Environments" at:
http://www.nyc.gov/html/doh/html/epi/moldrpt1.shtml
Fungal Contamination in Public Buildings: Health Effects and Investigation Methods
http://www.hc-sc.gc.ca/ewh-semt/pubs/air/fungal-fongique/index_e.html
Fighting Mold - The Homeowners' Guide. Publication CE 08, Canada Mortgage and Housing Corporation (CMHC)
http://www.cmhc-schl.gc.ca/en/burema/gesein/abhose/abhose_ce08.cfm


Updated - 16 July 2009

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