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Air purification (Metamorfoze)

How worthwhile is air purification for the preservation of paper?

Hidden away in the engine rooms of archive and library depots throughout the Netherlands are heavy-duty fans pumping thousands of cubic meters of air through special chemical filters, 24 hours a day. But is this really worthwhile?

07 Internationale experts tijdens de expertmeeting in 3

International expert meeting on air pollution in 2009.

Since the 1990s air purification is standard practice for archive and library depots. The Archives Regulation sets out the technical details of air purification in law.


However, this Regulation is a double-edged sword. Regulations do create clarity about how to act, but as soon one takes effect, the awareness of the underlying arguments, assumptions and unexplained details fades away and scientific discussions end.

... versus cost effectiveness

The discourse of today forces a reopening of discussion. Since the economical crisis, the costs of climate control and air purification stand out more clearly against shrinking budgets. The question of cost effectiveness of air purification for the preservation of paper has been thrust into the foreground.


To find the answer, the RCE along with other organizations, analysed air purification in four leading international institutions, the National Archives and the National Library in The Hague, the National Museum in Copenhagen and the Swiss National Library in Bern,

A threat or not really?

Since the 1980s research on the effects of air pollution on paper and leather has resulted in a huge amount of technical specialist literature. The implicit message of this paper pile: air pollution poses a threat to paper - or not really. In any case, from 1994 the ventilation systems of all state archives were fitted with chemical filters as a precautionary measure.

Archive Regulation

But how great exactly are the harmful effects of air pollution on paper? Differences reported in various studies in yellowing and embrittlement are tiny and might just as well have been caused by other differences in storage conditions. The analysis of the RCE and partners showed that the expected influence of air pollution is, in fact, minimal. This finding contradicts the menace conjured up by the literature.


Based on the recent research results the National Library and National Museum have adapted their policy. In consultation with the Government Buildings Agency (RGD), the National Library will not be fitting chemical filters in newly renovated air conditioning installations and the National Museum has scrapped the chemical filters from a depot about to be built. The National Archives and the Swiss National Library need more time for a differentiated approach.


At the initiative of the RCE and under the umbrella of the Sustainable National Depot, various heritage institutions in the Netherlands are seeking ways to store their museum collections in more energy-efficient and cost-effective ways. This can be achieved by making depots as airtight as possible. The research has made clear that the effects of both internal and external air pollution are negligible for paper collections.