## 3 Results
### Observation of Gaseous Components and Analysis of Agricultural Chemicals in Greenhouse
On the other hand, the maximum concentration of NO\({}_{2}\) was observed between 10 and 11 a.m., which was about 1 to 2 h later than the time when the maximum concentration of NO was observed. This is interpreted as NO changing into NO\({}_{2}\) by typical photochemical reaction. The change of NH\({}_{3}\) concentration overtime was relatively constant at dawn and nighttime, like NO and NO\({}_{2}\); and after 8 a.m., the NH\({}_{3}\) concentration started to rise, and showed the maximum concentration at 11 a.m. After that, it gradually decreased until 5 p.m., and then remained relatively constant. It is difficult to understand the characteristics of the primary emission source, because  
Figure 4: Concentrations of PM\({}_{2.5}\), NH\({}_{3}\), NO and NO\({}_{2}\) measured in a green house. fertilizer, crop and soil characteristics, crop management, and meteorological conditions have multiple impacts on the emission of NH\({}_{3}\) in the agricultural environment [15; 16; 17; 18]. NH\({}_{3}\) in the greenhouse can be evaporated by temperature rise based on the time when the NH\({}_{3}\) concentration increases and reaches the maximum during the daytime. As a result of measuring the level of PM\({}_{2.5}\) and precursor gases for 28 days in the greenhouse, which is a relatively closed system, agricultural activity did not significantly affect the increase in PM\({}_{2.5}\). However, an increase in precursors, such as NO, NO\({}_{2}\) and NH\({}_{3}\), was observed from agricultural activities; and it was found that each material increase was based on temperature and photoreaction. VCCs are air pollutants with a boiling point of 50 to 260 \({}^{\circ}\)C at room temperature (RT) and atmospheric pressure. Among VOCs, benzene, toluene, ethylbenzene, and xylene (BTEX) are all designated by the EPA as hazardous air pollutants (HAPs) [22; 23]. In terms of PM\({}_{2.5}\) formation, oxygenated volatile organic compounds (OVOCs) generate particulates by themselves in the atmospheric environment through the process of condensation and nucleation, and are also involved in the photochemical reaction of ozone (O\({}_{3}\)) and nitrogen oxides, which has an impact on the generation of secondary organic aerosols (SOA) and secondary nitric aerosols [24; 25; 26]. In agricultural areas, VOCs are emitted in various forms. VOCs are formed as products of resistance to environmental factors that put stress on plant growth [27; 28]. This means that they are caused by beneficial ecological functions that can promote plant health, such as repelling predators and parasites that affect plant growth, or attracting beneficial animals [29; 30; 31]. It is also suggested that in agricultural environments, VOCs are emitted when a pesticide is sprinkled. According to a previous study, it was reported that VOCs of 0.6-5000 ppb were contained in the wastewater of pesticide plants, which raised concerns about the increase in VOCs in agricultural soil [32]. Another previous study reported the increase in benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS), which are major components of pesticides in the soil by agricultural activities [33]. Based on these results, it was suggested that VOCs-based organic solvents contained in pesticides are directly discharged into the air and soil by agricultural activities. Therefore, in this study, VOCs content was investigated by analyzing pesticides used in agricultural areas. To investigate the origination of PM\({}_{2.5}\) in agricultural areas, the VOCs contained in four kinds of agricultural chemicals were analyzed. We selected pesticides, fungicides,  
Figure 5: Time-series concentrations of PM\({}_{2.5}\), NH\({}_{3}\), NO and NO\({}_{2}\). herbicides, and vapor deposition agents that are available in the market and are mainly used in apple orchards. The reason for selecting the agricultural chemical used in the apple orchard is that the main crop in the orchard area investigated in this study is apple. Table 1 shows the concentrations of VOCs contained in agricultural chemicals.