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INTEGRATED EXPOSURE FOR RISK ASSESSMENT IN INDOOR AIR (INTERA)

A review of existing indoor air pollutant exposure data and models

LAY SUMMARY (Work Package 1)

Background

Exposure to indoor air pollutants is one of the primary environmental health stressors,

particularly given that people in developed countries are inclined to spend around 80-90% of

their time indoors. Concentrations of indoor air pollutants are determined by a number of

factors, such as infiltration from outdoor pollutant sources, emissions from indoor sources such

as building materials, furniture, burning of solid fuels, and tobacco smoking (environmental

tobacco smoke or ETS), electrical appliances, the use of household cleaning products and

indoor climatic variables.

The Integrated Exposure for Risk Assessment in Indoor Environments (INTERA) project was

commissioned by CEFIC under the Long Range Research Initiative to develop novel methods to

bring together exposure and risk information relating to household air pollutants within home

settings in the European Union (EU).

Given the variability in human behavior, in how and where we live, and the resultant different

levels of contamination between different indoor environments, defining optimal methodologies

for predicting indoor exposure to chemical and non-chemical contaminants involves developing

a comprehensive full chain methodology that can be applied within the context of both research

and policy development. Work Package 1 represents the first step towards achieving these

objectives and involves determining the main parameters influencing exposure, and reviewing


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and summarising existing indoor exposure data across inhalation, ingestion and dermal

exposure routes. In addition it identifies existing and developing indoor pollutant modeling

methods.

Method

A systematic approach was used to conduct searches of the online databases Ovid Medline and

Pub Med, limited to studies undertaken since 1995, with full text published in English, and

involving human beings. Studies carried out in countries that were not members of the EU, or

that did not collect primary data in at least one home were excluded. Searches were undertaken

for inhalation, ingestion and dermal exposure routes. Approximately 200 potentially relevant

publications were exported into an online bibliographic database (RefWorks, Proquest Inc) for

further scrutiny.

The search strategy for the review of existing and developing models of indoor air pollution

levels involved examining scientific literature and project reports available from academic

institutions, funding bodies and other organizations with a research or consumer interest in

indoor air quality (IAQ). In addition to the collective experience and knowledge of the INTERA

team, the main snowball technique starting points were the US EPA IAQ webpage

(http:/www.epa.gov/iaq), the book Exposure Analysis (edited by Ott, Steinemann and Wallace,

2006, page 459), reports from the HEIMTSA project, (Health and Environment Integrated

Methodology and Toolbox for Scenario Assessment) available from http://www.heimtsa.eu/ and

specific papers where indoor models have been used such as EXPOLIS from the project

website athttp://www.ktl.fi/expolis.
http://www.heimtsa.eu/http://www.ktl.fi/expolishttp://www.ktl.fi/expolishttp://www.ktl.fi/expolishttp://www.ktl.fi/expolishttp://www.heimtsa.eu/


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Whilst not strictly falling under the definition of IAQ models, studies related to risk assessment

of IAQ or databases used to populate IAQ modeling techniques have been included for reasons

of clarity.

Results

A total of 57 scientific publications relevant to exposures generated by the use of household

consumer products have been identified and reviewed. These include the main indoor pollutant

chemical groups to be considered by future work packages in the INTERA project. These

groups are: radon (5 papers); carbon monoxide (3 papers); carbon dioxide (2 papers); nitric

oxides (15 papers); aldehydes (10 papers); polycyclic aromatic hydrocarbons (PAHs) (2

papers); polybrominated diphenyl ethers (PBDEs) (5 papers); nicotine (3 papers) and volatile

organic compounds (VOCs) (12 papers).

Two major types of computer simulation techniques for studying airflow and contaminant

transport in buildings were identified: mass-balance models and computational fluid dynamic

(CFD) techniques. CFD models take a microscopic view of IAQ by examining pollutant

concentration distributions within a room and require a high computational demand. It is outwith

the scope of INTERA to assess variations in concentrations in one room, therefore CFD models

have not been included in this review.

Mass balance modeling takes a macroscopic view of IAQ by evaluating average pollutant

concentrations in different zones of a building as contaminants are transported through the

building and its heating, ventilation and air conditioning system (HVAC), and constitute the

majority of the currently available models. The strength of these models is that the simulation of

air pollutant concentrations may be compared with results from experimental measurements.

They can be split into three types: micro-environmental models (eg INDAIR); multizone models


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(eg CONTAM, RISK); and regression models which are often incorporated as an indoor air

module of integrated exposure assessment software packages (eg ConsExpo 4.0 software

package, RIVM, 2005) and deal with exposure from consumer products via indoor air exposure.

A total of 29 indoor pollutant modeling methods are presented, several of which are still under

development.

Conclusions

This work package has reviewed the recent literature where measurement of inhalation, dermal

and ingestion exposure to indoor pollutants has been performed in domestic or home-life

settings within the EU. A comprehensive database of scientific literature has been established

with a total of 57 papers satisfying the review inclusion criteria. Summary data is provided with

full copies of these scientific papers being held on an online resource and made available to

members of the INTERA study team for assimilation into WP2 and other elements of the full

chain modeling process.

The review process has also identified a total of 29 relevant model systems that deal in some

way with indoor air exposure characterization. Some of these are broad in scope focusing

primarily on risk while others are much narrower examining single stage processes of any given

individuals exposure profile. The report provides web-based links to these models and where

possible details of final reports and any peer reviewed publications arising from these models.

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