Indoor air quality can be affected by indoor sources, ventilation, outdoor levels, and removal. Various indoor and outdoor combustion sources make nitrogen dioxide(NO2), which is a by-product of high temperature fossil fuel combustion. Especially, the presence of gas ranges and smoking have been identified as two of the major factors contributing to indoor NO2 exposures. In this study, the relative efficiencies for NO2 removal by a large number of materials are presented. This work has demonstrated that reactions with indoor surfaces represents a significant sink for NO2, and that these reactions currently are effecting a considerable degree of control over indoor NO2 levels. It seems that this control could be enhanced by judicious selection of furnishings and construction materials. Improved understanding of that rates and mechanisms of the removal process will permit optimization of the process for indoor air quality improvement.

Burning mosquito coils in indoor environments maygenerate smoke that can control mosquito effectively. This practice has been used in numerous households in Korea. However the smoke may contain air pollutants of health concern. We conducted the present study to characterize the emission from two common brands of mosquito coils from Vietnam and Malaysia, respectively. We measured mass emission of air pollutants of nitrogen oxides (NOx), fine particulate(PM2.5), formaldehyde (HCHO), total volatile organic compounds (TVOCs), carbon monoxide (CO) and carbon dioxide (CO2) in completely closed chamber. Air pollutants concentrations resulting from burning mosquito coils could substantially exceed health-based air quality standards orguidelines. Under the same condition, air pollutants were measured by cigarette smoking to compare mosquito coil. Burning one mosquito coil would release the same amount of PM2.5 mass as burning 20~58 cigarettes. The emission of HCHO from burning one coil can be as high as that released from burning 27 cigarettes.

Indoor air quality can be affected by indoor sources, ventilation, decay and outdoor levels. Although technologies exist to measure these factors, direct measurements are often difficult. The purpose of this study was to develop an alternative method to characterize indoor environmental factors by multiple indoor and outdoor measurements. Using a mass balance model and regression analysis, penetration factor (ventilation rate divided by the sum of ventilation rate and deposition constant) and source strength factor (source strength divided by the sum of ventilation rate and deposition constant) were calculated using multiple indoor and outdoor measurements. Subsequently, the ventilation rate and NO2 generation rate were estimated. Mean of ventilation rate was 1.41 ACH in houses, assuming a residential NO2 deposition constant of 0.94 hr-1. Mean generation rate of NO2 was 16.5 ppbv/hr. According to house characterization, inside smoking and family number were higher NO2 generation rates, and apartment was higher than single-family house. In conclusion, indoor environmental factors were effectively characterized by this method using multiple indoor and outdoor measurements.