Understanding New Building Flush-Outs

Understanding New Building Flush-Outs


Historical Context

Flushing out of the chemicals that are gassing off from new building materials is a relatively new general practice that has been proving its value for well over twenty-five years in the Environmental Health field. Canadians for A Safe Learning Environment (CASLE) has developed a great deal knowledge on the need for clean air in new buildings, as well as experience with effective methods to achieve cleaner air in new buildings. The use of flush-outs grew out of years working with people with Environmental Illnesses (EI) and Multiple Chemical Sensitivity (MCS). CASLE’s CEO worked as a patent educator for Nova Scotia’s pilot Environmental Medicine Clinic in the 1990’s, and our CEO and some of our current board members are still working as patient educators. They were taught by Environmental Health professionals here and through similar clinics in the United States and the UK about what was being successfully practiced to create healthy homes and workplaces for people with EI/MCS.

Canada’s Canada Mortgage and Housing Corporation (CMHC) has also done much work on this subject, and published what it learned through various studies conducted in the model safe house it constructed for research purposes in Ottawa. Choosing least-toxic/low emission building materials is the first step in avoiding exposures to chemicals from building materials.

Through experience, it has been found that by pairing low-emission product choices with a 6 to 8 weeks flush-out, or longer if possible, (that is, after the construction is complete and the systems are working) most people with EI/MCS can tolerate new or renovated spaces well. There are always exceptions, but most can be accommodated with reasonably similar procedures.

Why Prevent Occupants from Exposure to Building Material Chemicals?

  • Schools contain a cross section of society. There are people in schools with a broad range of health challenges, including asthma and other respiratory illnesses, Chemical Sensitivity or Environmental Illnesses of varying severity, and more.
  • Some report asthma, migraines, rashes, brain fog, weakness, flu-like symptoms, and more when using new and renovated buildings that are still gassing off new building materials. Some previously healthy students and staff have reported long term health consequences from working in schools that are still gassing off new building materials.
  • Research has also been showing subtle and not-so-subtle effects from volatile organic compounds (VOCs) and low-level pollutants on the health and performance of even normally healthy people.
  • Even if we do not know the exact effects of many chemicals, we do know that each molecule of foreign substance that is taken into the body has to be dealt with by the body in one way or another. Some are removed using nutrients and body systems, some do damage on their way through, some are changed to other materials by body processes, (some of these new materials are more harmful than the original). We also have learned from such studies as “Our Toxic Nation” that many foreign chemicals are stored in body tissues. There they can do more damage or they will be released later and impact body systems then.
  • In recent years we have seen a notable change among medical scientists and toxicologists who now recognize hazards from long term, low level chemical exposures. In the past “the dose makes the poison” was the standard.
  • Multiple airborne chemicals from different sources can combine to create new airborne compounds.
  • Children tend to be more vulnerable members of society. For example, the brain continues to develop until age 18 to 21. See Why Children are More Vulnerable

Why a Six to Eight Week Minimum?

  • We know construction scheduling often falls behind and causes flush outs to be shortened. Many things happen. Insisting on a 6 to 8 week flush out combined with low emission materials and with the HVAC working round the clock gives very little wiggle room, so this is a minimum recommendation.
  • For new schools, the goal to do a flush-out before building occupancy has challenges. Six to 8 weeks usually refers to the day the students enter. However, teachers are in the building preparing for the school year at least a week or two before opening day. With new schools, staff need more time because everything must be set up, new equipment needs to be learned, and more. In order to give teachers a minimum 5 to 6 week protective flush out, the 6 to 8 weeks prior to opening day target is necessary. More is better.
  • We have also found that the heating and ventilation systems (HVACS) always require adjustments and that there are often problems with the system in the first weeks and months. Requiring an early flush-out provides a target to have the system operating earlier.
  • Of all the buildings that we have worked on, schools are the ones that simply cannot open late. The impact on students’ academic and work prospects require that they not miss school time, especially in the senior high years. It is better to have a contingency plan in place so that possible construction delays or other delays do not force students and staff into an unprepared building. Shortening building flush-out is not a contingency plan.
  • As mentioned, this time frame has been shown to generally work for people with EI/MCS when coupled with less toxic materials selection. However, valuable information comes from documenting concerns, complaints and health symptoms reported by building occupants. These can help identify and correct related building deficiencies and can help point to best practices for future buildings.

What About Air Quality Testing Instead?

Air quality testing cannot be relied upon to determine if a building is ready for occupancy. The human body is much more sensitive to low level emissions than was previously believed. The test measures of airborne TVOC and VOC levels may not accurately reflect what can impact the human body.

“Susceptibility to indoor contaminants varies greatly from person to person, perhaps by several orders of magnitude. Building managers and indoor air quality specialists need to be on the lookout for these “canaries”, individuals who may be more susceptible to low-level air pollutants, for a variety of reasons…these individuals can often help locate problem sources that are not identifiable by air sampling or other testing methods.” (Spengler, Samet, McCarthy, Indoor Air Quality Handbook, McGraw-Hill, 2001, Chapter 27 Introduction.)

As an example, in one school opened in Halifax, low-emission/less-toxic materials were used, and the TVOC readings done by a reputable company were reported to be 0, yet health complaints were many and sometimes severe and life-altering.

Controls such as choosing low-emission/ less-toxic building materials coupled with a functioning HVAC during a six to eight week minimum flush out have been shown to work well for those with conditions such as EI/MCS, asthma, migraines and more.

Please see our website www.casle.ca for articles on testing air quality, on Revised Building Readiness Guidelines for New Schools and on how to conduct a flush-out.

Go to The Canadian Human Rights Commission (CHRC) site for information on accommodating those with EI/MCS:




Go to http://drclaudiamiller.com/ to learn more about the human body and low level chemicals.