Residential Indoor Air Pollution in Qingdao

Objectives To understand the urban residential indoor air pollution characteristics in Qingdao City, and to provide reference guidance and suggestions for indoor air quality investigation in both urban and rural areas.

Methods The 59 households and 118 monitoring sites, including living room and bedroom, were randomly selected in 2018. The temperature, relative humidity, PM_2.5, PM₁₀, formaldehyde, benzene, toluene, xylene, NO₂, total count of bacteria and total count of fungus were measured during the non-heating and heating period.

Results The indoor air pollution was mainly caused by total count of fungus, nitrogen dioxide, formaldehyde, PM₁₀ and total count of bacteria during the non-heating period and the unqualified rates were 48.4%(61/126), 37.3%(47/126), 20.6%(26/126), 4.76%(6/126) and 3.97%(5/126), respectively. The indoor air pollution was mainly caused by PM₁₀, PM_2.5, total count of fungus, total count of bacteria and formaldehyde during the heating period, and the unqualified rates were 39.8%(43/108), 37.0%(40/108), 28.70%(31/108), 9.26%(10/108) and 7.41%(8/108), respectively. The concentrations of nitrogen dioxide, PM₁₀ and PM_2.5 indoor were significantly different with those outdoor in the non-heating period (t values were 14.3, 7.10 and 4.95, respectively, P < 0.01). While the difference between concentrations of nitrogen dioxide, PM₁₀ and PM_2.5 indoor and those outdoor were insignificant in the heating period (t values were 1.08, 0.35 and 1.53, respectively, P>0.05). Spearman correlation analysis showed that the total count of bacteria was positively correlated to formaldehyde and total count of fungus(r_s values were 0.303 and 0.248, respectively, P < 0.01), and the total count of fungus was positively correlated to temperature, the relative humidity and nitrogen dioxide (r_s values were 0.273, 0.280 and 0.235, respectively, P < 0.01) and negatively correlated to benzene, toluene and xylene (r_s values were -0.208, -0.261 and -0.181, respectively, P < 0.01).

Conclusions Formaldehyde, nitrogen dioxide, fungus and particulate matters are the main urban residential indoor air pollutants in Qingdao City.