Total volatile organic compound concentration and its influencing factors in urban indoor air after decoration

The indoor total volatile organic compound (TVOC) concentrations and their relationship to potential influencing factors were evaluated. Samples (n = 2302) were collected from 2007 to 2009 both in old structures and new construction in the city of Hangzhou from bedrooms, sitting rooms and studies that had been decorated within the previous year. The average TVOC concentration in all the newly decorated rooms was 0.65 +/- 0.69 mg/m(3). 35.8% of samples exceeded the China standard. Over the past 3 years, the TVOC concentration decreased and then increased (P < 0.05). The percentage of samples exceeding the China standard in the three rooms decreased in the following order: sitting room > study > bedroom. The characteristics of the TVOC source were a key factor influencing the TVOC concentration. In addition, the TVOC concentration was also (P < 0.05) related to the temperature, humidity, time from the end of decoration to sampling (DR), and the amount of time windows and doors were closed before sampling (DC). The temperature and humidity were less important than the DR and DC. A model to relate the TVOC concentration to the five factors (temperature, humidity, source, DR, and DC) was established based on 288 samples (R (2) = 0.83). The model illustrated that the time for the TVOC concentration to meet the China standard was different for the various rooms, and when the other factors were fixed, the impact of DC (t (1)) on the TVOC concentration could be quantified as (((t (1)+1)/2)(0.212)-1)x100%.