Indoor air quality: ANSES proposes two guideline values for acetaldehyde

The quality of air inside buildings is a public health concern in France and many other countries. This is because the indoor environment provides a wide variety of situations giving rise to exposure to chemical or microbiological contaminants, ranging from simple discomfort irritating odours , eye irritation, etc.) to the onset or aggravation of diseases, especially respiratory disorders. Moreover, in temperate climates, each individual spends on average 85% of their time in enclosed environments, a majority of which is in the home.

To address the health issue represented by indoor air quality, ANSES issued an internal request in 2004 to develop indoor air quality guideline values (IAQGs). These are defined as airborne concentrations of a chemical substance below which no health effects or harmful impact on health is expected for the general population, as current knowledge stands. They aim to protect the general population from any adverse effect associated with exposure to this substance via air. The IAQGs proposed by ANSES provide a basis for the authorities to establish regulatory values for monitoring indoor air quality.

In this context, ANSES is today publishing its Opinion on the development of two IAQGs for acetaldehyde, for short- and long-term exposure.

Sources of exposure to acetaldehyde and its health effects

There are many sources of acetaldehyde in the indoor environment: combustion processes involving organic matter (smoking, cooking, domestic wood heating), building and decorating materials, furnishing products and everyday consumer goods (floor cleaners, wooden flooring , laminates, glues, varnishes, paint strippers, paving and flocking, etc.).

In over 98% of French homes, the concentration of acetaldehyde in the indoor environment is higher than or equal to that measured in outdoor air.

The main effects observed in humans after exposure to acetaldehyde vapours are irritation of the eyes, skin, and upper and lower airways, extending to bronchoconstriction in asthmatics. In addition, acetaldehyde has been classified as possibly carcinogenic to humans (Group 2B) by the International Agency for Research on Cancer (IARC) since 1999.

Agency conclusions and recommendations

The Agency proposes two IAQGs. The first value was established to protect from effects occurring after short-term exposure: 3000 µg.m^-3 for an exposure duration of 1 hour. Its aim is to safeguard the population from one-time or intermittent exposure to high levels associated with a particular activity. Acetaldehyde is highly irritant to the respiratory tract. After exposure for just a short period of time, people with asthma may develop bronchoconstriction.

A second value was established to protect from the long-term effects: 160 µg.m^-3 for an exposure duration of one year or more. This is to protect the public exposed on a regular basis to levels that are lower yet permanent (background levels). In cases of repeated exposure, the irritating effects of acetaldehyde on the upper respiratory tract can lead to damage of the epithelium. Concerning this IAQG, there is currently no recommended measurement method for comparing observed levels with the proposed value of 160 µg.m-3. For this reason, the Agency is recommending that suitable measurement methods be developed and validated.

In addition, the Agency is recommending that studies be undertaken to assess exposure to several aldehydes found in indoor air –- especially when formaldehyde, acrolein and acetaldehyde are measured simultaneously – as well as their health consequences, with a view to developing a guideline value for a mixture of aldehydes.

Lastly, ANSES emphasises the importance of raising public awareness about simple measures that could effectively reduce indoor air contamination, such as airing rooms by opening windows and using extractor hoods, regarding the main sources of acetaldehyde in indoor air (cooking, domestic wood heating, tobacco smoke).