To explain these findings, we suggest that pollution indoors is caused by benzene entering from the streets outside, as shown by the respective seasonal trends.
The reason why, in general, indoor pollution is higher than the outdoor one, even if it reflects its seasonal trend, might be due to a lack of balance among input from outside and inside removal.
In other words, the house itself might act as a flywheel because of the absorbing power of the surfaces of walls, floors and furniture.
The hypothesis is supported by the fact that the phenomenon is negligible in Southern European towns while is noteworthy in Northern European countries. In Northern towns moquette, linoleum and wood linings often replace tiling, marble and bare walls typical of Southern towns."
(Urban benzene and population exposure, Fondazione Salvatore Maugeri-IRCCS, Padova, Italy, 2000)
The research, published on the scientific magazine Nature (Volume 404, page 141), was carried out by an international team of researchers: V. Cocheo, P. Sacco, C. Boaretto, E. De Saeger, P. Perez Ballesta, H. Skov, E. Goelen, N. Gonzalez, A. Baeza Caracena.