It has been reported that indoor formaldehyde concentrations
typically decrease with time, usually falling below 0.1 mg/m3 about
6 months after remodeling (Chi et al., 2007; Lin et al., 2005a; Zhang et
al., 2007a). However, data in Table 4 shows that levels can remain high
even up to 1 year after remodeling. In newly remodeled bedrooms in
11 cities of Jiangxi province, average formaldehyde levels measured
0.25 mg/m3. In one instance, after 2 years of remodeling, formaldehyde
levels still remained at 0.138 mg/m3 (Zhang et al., 2007b).
Seasonal fluctuations in formaldehyde levels also occur, with summer
levels on average higher than winter levels in all regions, except
Shizuishan (Yao et al., 2005).