## 4 Discussion  
Safety instructions on containers are often written in unfamiliar languages. Since most of the participants only had an elementary school level of education, they might have difficulty reading or found instructions difficult to follow [48; 49; 50]. The respondents (86.7%) also indicated that they usually checked their equipment prior to use. This was similar to other studies performed in Thailand, where it was reported that about 97% of the farmers checked the condition of their equipment before using them [51]. Most respondents reported that they never smoked or drank alcohol while spraying pesticides, which confirmed the results of a similar study that reported more than half of their respondents not smoking or drinking water while working [52; 53]. Most of the participants wore masks while spraying, which was relatively consistent with the results of other studies from Ethiopia and Thailand [49; 54; 55]. The results showed that most of the samples collected during pesticide application had detectable VOCs and SVOC compounds, in part because the farmers hung the mechanical sprayer on their shoulders, very close to their breathing zone. Since farmers may have been exposed to chemicals including VOCs, SVOCs, and pesticides, long-term exposure and the possible resultant health effects have been suggested for further study [54; 55; 56; 57; 58]. Eleven VOCs compounds were found in these air samples including Methyllene Chloride; Ethylbenzene; o-Xylene; m-Xylene; p-Xylene; Styrene; 1-Methyl Ethylbenzene; Tert-Butyl Benzene; 1, 3, 5-Trimethyl Benzene; 1-Methyl Propyle Benzene; and 1, 4-Dichloro Benzene. However, the farmers' exposure to these chemicals were at less than 50% OELs. The agricultural machinery used primarily emits NOx, PM2.5, PM10, VOCs, HC, CO, and SO\({}_{2}\)[10; 59]. Our results were similar to those in previous studies measuring emissions produced by gasoline combustion engines used in agricultural machinery. For example, a \begin{table}
\begin{tabular}{c c c} \hline \hline
**Symptoms** & **Frequency** & **Percentage** \\ \hline Skin Symptoms & & \\ Skin rash/itching/burning & 6 & 20.0 \\ Tingling/numbness of hands & 9 & 30.0 \\ muscular twitching and cramps & 8 & 26.7 \\ Respiratory Symptoms & & \\ Chest pain & 4 & 13.3 \\ Cough & 13 & 43.3 \\ Running nose & 13 & 43.3 \\ Difficulties in breathing & 12 & 40.0 \\ Shortness of breath & 7 & 23.3 \\ Irritation of the throat & 12 & 40.0 \\ Central Nervous System Symptoms & & \\ Excessive sweating & 9 & 30.0 \\ Nausea & 15 & 50.0 \\ Vomiting/Dizziness & 6 & 20.0 \\ Excessive salivation & 2 & 6.7 \\ Abdominal pain/Stomachache & 4 & 13.3 \\ Headache & & 13 & 43.3 \\ Eye Symptoms & & 10 & 33.3 \\ Lxtermation & 13 & 43.3 \\ Irritation & 10 & 33.3 \\ Blurred Vision & & 10 & 33.3 \\ Neuro Muscular Symptoms & & \\ Difficulty in seeing & 6 & 20.0 \\ Restlessness & 9 & 30.0 \\ Difficulty in failing asleep & 6 & 20.0 \\ Trembling of hands & 5 & 16.7 \\ Irritability & 6 & 20.0 \\ Anxiety/ anxiousness & 5 & 16.7 \\ Memory Problems & 6 & 20.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Symptoms related to chemicals exposure (\(n=30\)). similar study conducted in Korea reported that 15 types of VOC emissions from a gasoline engine were detected in or near the breathing zone of the applicator [60]. For respirable particulate exposure, the results showed that the highest concentration (1.83 mg/m\({}^{3}\)) occurred during harvesting. This was not unexpected as it is the dry process with high agitation. These results are similar to those in previous studies that reported dust generation from farming activities [22; 23; 24]. Most participants mentioned symptoms related to the central nervous system and the respiratory system. The average temperature in the study area was higher than 30 \({}^{\circ}\)C [61]. Previous studies reported that their symptoms increased in hot weather [62; 63]. Thus, the symptoms that farmers thought were related to gasoline engine combustion by-products may actually come from working in hot weather.