Indoor Air Quality

9. What kind of research on indoor air quality is needed?

• 9.1 How much information on indoor air quality is available today?
• 9.2 What questions about human exposure need to be answered?
• 9.3 What research is needed regarding health effects of indoor air pollutants?
• 9.4 Are existing measurement standards for indoor air quality adequate?

9.1 How much information on indoor air quality is available today?

It is necessary to investigate how people are exposed to pollutants in indoor air

The chemicals and particles present in indoor air and their concentrations vary greatly across different indoor spaces and in different EU countries. The data for risk assessment are scarce and often insufficient to account for all the variability and complexity in the indoor environment.

Information is available on the levels in indoor air of some well-known pollutants (such as carbon monoxide, nitrogen oxides, VOCs, etc.) in Europe. These data help identify the compounds with highest concentrations and of greatest concern. Effects and risks for most of these “usual” pollutants are known so it is possible to create strategies to mitigate their impact. However, new sources of pollutants have emerged (such as VOCs from air fresheners) and some of them may react to produce secondary pollutants whose effects are unclear.

At present, outdoor air quality is monitored for some pollutants (e.g. particulate matter, nitrogen oxide, ozone) but the data cannot be extrapolated to predict the concentrations that reach the inside of buildings, because several local factors contribute to the access of pollutants indoors (e.g. tightness of the building). Instead, the levels of pollutants in indoor air also have to be measured, though this may be difficult to do in a systematic way in private spaces. To help risk assessment it is also necessary to monitor other factors such as the ventilation rate, the level of carbon dioxide, general cleanliness and signs of dampness.

Guideline values should be provided for key pollutants as well as guidance on how to deal with them. More...

9.2 What questions about human exposure need to be answered?

The existing data on indoor air pollutants should be reviewed and the major air pollutants and their levels in each Member State of EU should be identified. It is a priority to compile a European-wide database that identifies data gaps and serves as background for future research.

Existing experiences and methods of doing risk assessments should be collected and organised.

The main research priorities are to:

• Investigate the variation of exposure to indoor air pollutants; identify which factors that can easily be measured could serve as indicators of the exposure of an individual.
• Identify the main sources of pollutants in indoor environment and quantify how much each source contributes to total concentrations in indoor air.
• Measure the emission levels of chemicals from consumer products in realistic use situations.
• Obtain information on harmful emissions in water-damaged buildings, such as toxic compounds released when building materials decompose.

Moreover it is recommended to:

• Identify, evaluate, verify and harmonize models that are currently used to predict the sources and the fate of indoor air pollutants.
• Evaluate potentially harmful emissions from indoor combustion processes.

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9.3 What research is needed regarding health effects of indoor air pollutants?

As far as health effects of indoor air pollutants are concerned, it is a high priority to increase research on:

• Effects due to exposure to mixtures of indoor air pollutants and methods for their evaluation.
• Adverse health effects of microbes and biological aerosols, especially those affecting other organs than the respiratory tract.
• The contribution of indoor air pollutants to childhood respiratory diseases.
• The exposure-response relationships, especially in vulnerable groups.

Moreover, research is needed on:

• Effects and risks of products which emit indoor air pollutants that can react in indoor air.
• Possible effects and risks of man-made nanoparticles in indoor air.
• The contribution of coarse, fine and ultrafine particles from indoor sources to adverse health effects.
• Persons suffering symptoms in buildings damaged by humidity.

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9.4 Are existing measurement standards for indoor air quality adequate?

The development of new measurement standards for indoor air quality are not a high priority, but existing ones should be validated and harmonized, in particular those concerned with indoor emissions from building materials and with biological agents.

Some of the measurement methods developed for outdoor air quality can also be applied to many indoor environments. In workplaces however, methods are often developed for higher concentrations of pollutants. More...