The Air Infiltration and Ventilation Centre’s new Technical Note 68 “Residential Ventilation and Health”

WouterBorsboom

Business Consultant indoor environment & energy efficiency

TNO, Delft, the Netherlands

wouter.borsboom@tno.nl

The AIVC Technical Note 68 “Residential Ventilation and Health” summarises studies that prioritise pollutants in the indoor environment and presents a summary of pollutants driving the indoor health risks and their sources. It also describes methods to reduce exposures of contaminants using different control strategies with a special emphasis on the role of ventilation.

TN68 is freely available for registered users to AIRBASE service. Click here to download the publication: http://www.aivc.org/resource/tn-68-residential-ventilation-and-health. Conditions for on-line access to AIVC publications are explained on AIVC website.

This AIVC Technical Note has been endorsed by the IEQ-GA, the Indoor Environmental Quality Global Alliance (www.ieq-ga.net), whose full members are:

·         The American Society for HVAC Engineers (ASHRAE)

·         the American Industrial Hygiene Association (AIHA)

·         Air Infiltration and Ventilation Centre (AIVC)

·         the Air & Waste Management Association (A&WMA)

·         the Indoor Air Quality Association (IAQA)

·         Federation of European Heating, Ventilation and Air-conditioning Associations (REHVA).

The vision of the IEQ-GA is to be the world’s primary source for information, guidelines and knowledge on the indoor environmental quality in buildings and places of work around the world.

Technical Note highlights

Exposures in houses constitute the major part of exposures to airborne pollutants experienced through the human lifetime. They can constitute from 60 to 95% of our total lifetime exposures, of which 30% occurs when we sleep. The airborne pollutants constituting these exposures have sources outdoors and indoors. Pollutants having sources outdoors penetrate building envelope through cracks, gaps, slots and leakages, as well as through open windows and ventilation systems. Indoor pollutant sources include humans and their activities related with hygiene, house cleaning, food preparation, laundry, etc.; also building construction materials, furnishing, and decoration materials; mould, bacteria, and fungi; tobacco smoking and combustion processes; as well as pollutions from pets and pests.

Exposure controls should be designed to minimize health hazards and avoid unwanted odours. To do this, we must identify the pollutants driving the health risks and identify the best control strategies for those pollutants. High concentrations are not necessarily indicative of a health hazard. Pollutant concentration data alone cannot be used to identify pollutants driving health hazards. Toxicity varies widely from pollutant to pollutant and extensive research has been undertaken to link exposures levels of specific pollutants to specific adverse health outcomes. Toxicology and epidemiology have traditionally been used to link concentrations/exposures to health outcomes. However, in-silico and in-vitro based assessments of toxicity are gaining prominence.

Several studies have attempted to prioritize pollutants for mitigation in the indoor environment based on the prevalence of disease in the community, occupant exposure estimates, and the research derived links between exposures and health outcomes. The key pollutants identified as driving chronic health impacts include: PM2.5 (particulate matter with a diameter less than 2.5 microns), mould/moisture, radon, environmental tobacco smoke (ETS), formaldehyde and acrolein. To reduce the exposure of contaminants different control strategies can be applied. The most effective are (1) source control and reduction of pollutant sources and (2) enclosure and encapsulation of sources. Ventilation plays a key role in reducing exposures that cannot be controlled by these measures. Effective local ventilation, such as cooker/range hoods, are critical for removing pollutants from periodic high emission sources such as cooking. Other contaminants can be removed by making use of mixing ventilation or displacement ventilation. The correct amount of ventilation is still an area of debate.

A new AIVC project is a study of the ratio behind ventilation regulation and standards in different countries. In many countries odour and moisture play an important role but some countries formaldehyde is an important source. Because the level of ventilation differs a lot over the several countries it is interesting if we can explain the reasons behind this. Although we already received valuable input of different countries your input is most welcome. We think it would be important information as input for a metric based on exposure.