Chapter 3 Results
3.2 Air sampling and analysis
Air sampling was conducted at 5 baking workplace, which located in Taipei City, New Taipei city, Hsinchu City, and Taoyuan City.
3.2.1 Factory 1
This is a well-known brand with 30 branches in Taiwan. The facrories is 4000 m2, and the sampling sites located in the working area on the second and third floor, as show in Figure 13. The first round of baking tasks was at 4 -10 am in 2F, and the second run baking process finished at 1:00 pm in 3F. There were around 30 workers at the sampling day
The air conditioner was on, and there was ventilation system connected to ovens only on the third floor, the ventilation system is 1.5 m above the tunnel ovens. There were 4 sampling sites at weiging room (A), 2F baking room (B), 3F baking room (C), and office in which sometimes microbial experiments were conducted and was next door to the weighing room (D).
As shown in Table 12, the concentrations of inhalable flour dust (0.55 mg/m3) exceeded TLV-TWA of 0.5 mg/m3, and the other one (0.41 mg/m3) exceeded 1/2 TLV-TWA. Ketones were detected at four sites and with higher concentration in weighing room. Even though it was lower than 1/10 PEL, the concentration of
acetaldehyde was much higher, especially in weighing room room. (Table 12) Because
the baking task ended before the time we stopped sampling, so if we adjusted the sampling time according to working time, the workers’ exposure concentration may be
3-5 times higher than detected.
As for the result of direct-reading instrument, Figure 14 indicated that the total VOCs reached 5000ppb, which was 21 times higher than non-working area (1F).
Moreover, the VOCs concentration opposite trends in 2F and 3F revealed that VOCs may accumulate in the working area during baking process; for instance, the
concentration in 2F was higher in the morning when the first run of baking task finished.
3.2.2 Factory 2
This was an industrial bakery which provided cakes for supermarkets and
convenient stores. The facrories was 1653 m2; Shaping and decorating was conducted on the first floor, and baking area was on the second floor. The task started at 8 am, and finished around 6 pm. There were 45 workers on the sampling day. The air conditioner was on, and there was ventilation systems connected to the tunnel ovens. There were 4 sampling sites at weiging room (A), 2F baking tunnel ovens (B), 3F cake decorating area (C), and office (D). (Figure 15)
The highest concentrations of inhalable dust were 0.82 mg/m3, which exceeded TLV-TWA of 0.5 mg/m3, and the concentration of 42 mins task-based personal sampling was 0.83 mg/m3. (Table 13) Both acetaldehyde and furfural were detected, and the highest concentration of acetaldehyde measured around tunnel ovens.
The TVOCs direct reading instrument showed the ventilation system on the second floor needed to be improved. After entering the factory, the TVOCs
concentration rose fastly, the highest concentration of TVOCs was 8,678 ppb, 21 times higher than concentration in office. (Figure 16) As shown in Figure 17Figure 18, the particle mass concentration in flour-weighing room and oil-spryed room were much higher than the concentration in office; total suspended particles were measured 0.697 and 9.47 mg/m3, respectively.
3.2.3 Retail store 3
This is a well-known traditional bakery in central Taiwan, with the surfaces of 331 m2. The stores mainly produced traditional cakes and moon cake. The materials were simple and no food flavorings were used during the process. The flexible amount of production depended on the selling condition. It was not the busy season for the store on the sampling day.
All windows and doors were open when air sampling was conducted, and there
were ventilation systems connected to ovens. There were 11 workers on the sampling day, and 4 sampling sites located at weiging and theiving area (A), baking areas (B), working table (C), and counter (D). (Figure 19)
Higher concentration of flour dust was detected around ovens and working table, which were higher than 1/2 TLV-TWA. The concentration of 2,3-heptanedione was higher beside counter, it may result from the cooling and packaging tasks conducted there.(Table 14)
This store is the only one without the detectable acetaldehyde, and coincided on the low direct-reading TVOCs concentrations, which were all lower than 400 ppb. As for total particle mass shown in Figure 20, the concentration peaked at 0.278 mg/m3 during pouring flour dust.
3.2.4 Retail store 4
This was not only a retail store but also a popular online shopping brand. With the surfaces of 116 m2, the store was on the first flour and cakes and breads were produced on the basement floor. They normally started to bake at 10 am, and there were 6 workers on the sampling day.
The only ventilation device was a window fan and the basement was crowded.
The 4 sampling sites were set up near weiging and mixing area (A), ovens(B), heating
area (C), and warehouse(D). (Figure 21)
The concentrations of inhalable dust at A, B, C sampling sites exceeded 1/2 TLV-TWA, the concentration at baking area reached 0.77 mg/m3. Workers did not wear any mask, and due to the poor air circulation in basement, it was also hot in the
afternoon. Higher acetaldehyde concentration detected at heating area and warehouse.
(Table 15)
3.2.5 Retail store 5
This was a chain store of a famous brand located in Taipei City, with the surfaces of 149 m2. Breads was sold on the first floor, and a small proportion of bread was produced on the second floor. The ventilation system were connected to ovens and air circulation was pretty good on the second floor. The 4 sampling sites were set up near working table (A), working table (B), counter (C), and stairs(D). (Figure 22)
The concentrations of inhalable dust were the lowest among 5 bakeries. Acetoin and acetaldehyde were detected at all sampling sites. (table 16) Most of breads were produced by their central factories in New Taipei City, and shipped to this chain store for selling. So there were lots of breads and cakes put besides counter and waited to be packaged and placed on shelves. This was probably the reason why the concentrations of TVOCs would be higher on the first floor than the second floor, which was over
2000ppb, 4-5 times the outdoor concentrations. (Figure 23)