The residents were elderly couples (in 22 dwellings) and individuals
(6 dwellings). They were non-smokers. They spent 83%
(median) of their time at home during the study period. All participants
were above 51 years of age and had been living in their
dwellings for at least four years. One couple was later excluded as
the study was terminated in their dwelling due to complaints of
noise, leaving 48 participants living in 27 dwellings for analysis.