In a European multidisciplinary research project concerning environmental d
iagnostics, museums have been selected, having different climate and pollut
ion conditions, i.e.: Correr Museum, Venice (Italy); Kunsthistorisches Muse
um, Vienna (Austria); Royal Museum of Fine Arts, Antwerp (Belgium); Sainsbu
ry Centre for Visual Arts, Norwich (UK). Some field tests investigated the
microclimate, the gaseous and particulate air pollution and the biological
contamination to suggest mitigative techniques that may reduce the potentia
l for damage in the long run. Potential risk factors are generated by imbal
ance in temperature and humidity, generated by heating, air conditioning or
ventilating system (HVAC), or the building structures, exchange of outside
air, or large visitor numbers. HVAC may also enhance indoor gaseous pollut
ion. Plants and carpets represent potential niches for bacterial colonisati
on. Pollutants and particles have been recognised having partly external an
d partly internal origin. Tourism has a direct negative impact, i.e. transp
ort of external particles, release of heat, vapour and CO2, as well as gene
ration of turbulence, which increases the deposition rate of particulate ma
tter. However, the main problem is that the microclimate has been planned f
or the well being of visitors during only the visiting time, disregarding t
he needs of conservation that requires a constant climate by day and by nig
ht. In some of these cases, better environmental niches have been obtained
with the help of showcases. In other cases, showcases worsened the situatio
n, especially when incandescent lamps were put inside. (C) 2001 Elsevier Sc
ience Ltd. All rights reserved.