Pinchin Environmental Newsletter (PEN #19)
Update on Risks and Control of Mould,
Lead and Silica
on Construction Projects
Introduction to Mould and Regulatory Responsibilities
Moulds are microscopic organisms, part of the Fungi kingdom of living matter, most of which reproduce through the production of massive numbers of spores. Mould spores can germinate within 24 hours of wetting and will produce the next generation of spores within 3 to 7 days. Current standards require that wetted materials be dried within 24 to 48 hours to
prevent mould growth1 .
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Mould growth may affect a wide variety of building finishes. Practically any organic building material will support mould growth. The most commonly contaminated building materials include drywall, carpet, ceiling tiles and wood products. Mould may also grow in wet crawlspaces or in dirt trapped in synthetic carpets and air conditioning units. All moulds require humid to damp surfaces at the immediate surface of a suitable nutrient base. Improperly managed construction projects may wet mould susceptible materials due to poor handling or storage, lack of protection from the elements or failure to heat when required.
In existing buildings, common indoor moisture sources include:
- single or recurring flooding (from roof leaks, faulty plumbing, sewer backups, for example),
- condensation in cool or humid areas,
- excessive use of water in cleaning and maintenance.
Once produced, mould spores readily become airborne and can remain in suspension for hours. Even mould growth hidden within wall cavities can be a source of occupant exposure,
as wind and thermal forces acting on these spaces spread mould particles into the occupied spaces. Mould spores remain potentially hazardous forever, so that water damage that occurred well in the past can still be an enduring cause of adverse health effects.
The adverse health effects of mould exposure in buildings are detailed in a guidance document published by the New York City Department of Health2 and widely accepted by public health and occupational health and safety agencies in Canada and the United States. Published in 2000, the New York City guidelines are widely quoted by health and safety professionals and regulators.
Several provinces have issued hazard alerts or bulletins acknowledging the potential for adverse health effects from mould exposure in buildings and advising adherence to the New York City protocol, or other professional standards.
The Ontario Ministry of Labour issued a Hazard Alert on Mould in Workplace Buildings, in December 20003 . The Alert, like the 2000 New York City guidelines, extends concern over mould growth to all types of mould. The Ministry advises that the sustained and/or extensive growth of visible mould inside buildings is unacceptable and a risk factor for health problems. The Alert states that constructors, supervisors and employers are responsible under the Occupational Health and Safety Act to take every precaution reasonable under the circumstances to protect a worker, including protecting workers from mould in workplace buildings. For specific direction, the Ministry refers employers to various professional standards and guidelines including the 2000 New York City guidelines.
Health Canada: Fungal Contamination in Public Buildings, 2004
Health Canada is the lead federal agency in Canada for the protection of public health. It also co-ordinates federal-provincial efforts in public and occupational health through the Federal- Provincial Advisory Committee on Environmental and Occupational Health (CEOH).
CEOH published a guide for the assessment and control of mould growth in general use buildings in 19954. This guide has been updated in 20045 . The intent of the 2004 document is to update the information and also to reconcile the document with more recent publications of several professional groups including the American Conference of Governmental Industrial Hygienists and the American Industrial Hygiene Association. The purpose of the document is to assist public and environmental health inspectors and consultants in the management of potential health risks associated with mould growth in public buildings.
The first section of the report presents a review of the health effects of mould growth in general use buildings, updated from the 1995 guidelines. The 2004 document considered fifteen epidemiological studies reported from 1995 to 2001 as well as ten animal studies. There appears to be a clear association between mould (or dampness) in buildings and asthma. Four of eight cross-sectional studies found a statistically significant association between mould exposure and either physician-diagnosed asthma or asthma-related symptoms (cough, wheezing or breathlessness). Of seven case-control studies, one found a significant association between “mold or dampness” and asthma, another found a significant association between mould and asthma but did not assess dampness, three found a significant association between mold and asthma but not between dampness and asthma and two found a significant association between dampness and asthma but not between mould and asthma. Several experimental studies on animals exposed to fungal cells, or extracts of fungal spores, found effects similar to those observed in humans in epidemiological studies.
The health effects review lead to the following conclusions and recommendation;
Consistent with the 1995 report, this updated review of health effects indicates that living or working in a building with material mould damage is harmful to health. Therefore, indoor mold growth in buildings should be prevented by appropriate control of moisture sources and by timely remediation of water damages. Mold growing in buildings should be removed under safe conditions using established remediation protocols.”
The 2004 Health Canada guideline provides updated advice on investigating a building for possible mould growth and steps for mould remediation. The first step in the mould investigation is an informed inspection, possibly with air sampling. Regarding air sampling, the Health Canada guideline differs from the advice of the New York City protocol and Canada Mortgage and Housing Corporation. Health Canada recommends air sampling as useful where investigators consider hidden mould growth to be a possibility. Health Canada also goes beyond the advice of the New York City protocol in recommending the collection and analysis of bulk or surface samples of mould-suspect materials. Not only can laboratory analysis distinguish between mould growth and mere water staining or soiling, but information on the types of mould present may assist the investigator in identifying the predominant water source and may be of interest to a physician treating a building occupant.
Once mould growth is confirmed, this information must be disclosed to the occupants. Among other things, this permits those with special sensitivities to unusual airborne mould exposures to consult with a medical professional about the advisability of their remaining in the building.
Fungal contamination should be quickly remediated using methods such as the New York City protocol (See discussion of the EACO mould work practices). Quality assurance of the remediation should be carried out according to standard protocols such as those of the American Industrial Hygiene Association6 . Quality assurance will usually include a program of inspections before, during and after the remediation work, considering work area isolation, ventilation, worker protection, work practices, and cleanliness. Usually some form of environmental testing is performed at completion of the work to check on an acceptable condition prior to removal of the containment barriers.
PEN # 19 "Update on Risks and Control of Mould,
Lead and Silica
on Construction Projects"
continues with
PEN #19 "Update on Risks and Control of Mould, Lead and Silica on Construction Projects"
Bruce Stewart CIH, ROH
Senior Vice President
Pinchin Environmental Ltd.
Presented at Construction Superconference
Toronto, November 29, 2004
1 US Environmental Protection Agency, Mould Remediation in Schools and Commercial Buildings, Washington DC, EPA-K-01-001, 2001.
2 New York City Department of Health, “Guidelines on Assessment and Remediation of Fungi in Indoor Environments”, New York, 2000. (http://www.ci.nyc.ny.us/html/doh/html/epi/moldrpt1.html)
3 Ontario Ministry of Labour, “Alert – Mould in Workplace Buildings”, 2000, (http://www.gov.on.ca/LAB/english/hs/alerts/a20.html.)
4 Committee on Environmental and Occupational Health: Fungal Contamination in Public Buildings: A Guide to Recognition and Management: Ottawa; Health Canada; 1995.
5 Health Canada; Fungal Contamination in Public Buildings: Health Effects and Investigation Methods; Ottawa;
ISBN 0-662-37432-0; 2004.
6 American Industrial Hygiene Association; Report of Microbial Growth Task Force; ; Fairfax, Virginia; 2001.
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