The odor evaluators from Guangzhou Environmental Monitoring Center Station demonstrate the process of smelling odors.
Upon arriving at the site of an odor complaint, the odor evaluators wait for the best moment to collect the most pungent gases. The picture shows Engineer Zhou Zhijun conducting routine monitoring and collecting odorous gases from a landfill.
Before setting out, the odor evaluators first evacuate the sampling bottles for collecting odorous gases in the laboratory.
■ Special Report Written by Information Times reporter Liu Fengguo
■ Special Report Photographed by Information Times reporter Huang Yimin
The sharp smell of oil fumes from the Sichuan restaurant next door has "attacked" Aunt Zhang again. After enduring it for many days, she could no longer bear it and called to complain to the environmental protection bureau. A few days later, two people came, each carrying a red box, looking like makeup artists. They stood at the door and explained to Aunt Zhang that they were from the environmental monitoring station, having received her complaint, and had come specifically to take some sample air back to smell.
This made Aunt Zhang curious: taking sample air back to smell? The staff with the boxes quickly explained that they mainly smelled whether the oil fumes emitted by the Sichuan restaurant exceeded standards. Of course, whether or not the standard was exceeded would be determined by their odor evaluators. Their odor evaluators specialize in smelling odors.
This sounded rare. After some time, the oil fumes from the Sichuan restaurant indeed became less strong. Aunt Zhang learned that the environmental monitoring station's odor evaluators had detected that the oil fumes from the Sichuan restaurant exceeded standards and ordered them to install additional equipment.
It turns out that these odor evaluators are really like judges, able to determine the guilt of odor emitters just by smelling. These people who deal with odors have a specific title, known as odor evaluators or olfactory assessors.
With advanced equipment available, why do they prefer to use humans to test odors? According to experts, instruments and equipment generally can only measure the concentration of single gases, often unable to judge the concentration of mixed odors. "If citizens report that a certain area or enterprise emits odors, but the instrument measurement results show that harmful gases do not exceed standards, and instruments cannot refer to subjective human feelings. In such cases, the method of human olfactory assessment can be used for testing, ultimately determining whether the odor exceeds standards."
Odor evaluators regularly smell the gases emitted from Guangzhou's landfills and sewage treatment plants, while also handling citizen complaints during normal times.
It seems that the role of these "noses" is truly indispensable. Whether something smells bad or not is entirely determined by these "noses." Are these people's noses more sensitive than ordinary people's? Don't they worry about being harmed by constant exposure to "odorous gases"? Will they become tainted with "odorous gases," affecting the lives of those around them? Information Times reporters found several "noses" from the Guangzhou Environmental Monitoring Center Station to investigate further.
Deep on-site investigation to apprehend foul odors
Equipped with vacuum bottles, waiting downwind, patiently guarding for the worst-smelling moment
Currently, there are nearly 50 certified odor evaluators (also known as "olfactory assessors") in Guangzhou's environmental monitoring system, with over 30 at the Guangzhou Environmental Monitoring Center Station (hereinafter referred to as "City Monitoring Station"). Once citizens complain about unpleasant odors, these "noses" spring into action. To convict the foul odors, the odor evaluators must first go to the "crime scene" and collect samples of the most pungent gases at the worst moments.
Engineer Zhou Zhijun worked as an odor evaluator at the City Monitoring Station for five years. He told reporters that any smell that causes discomfort, or any smell different from normal air, falls within the jurisdiction of the odor evaluators. He said that during his five years as an odor evaluator, the majority of complaints he handled were related to the catering industry, food processing plants, and fragrance and flavor production enterprises.
In 2005, Zhou Zhijun and his colleagues dealt with a complaint about a soy sauce factory. At the time, a suburban soy sauce factory angered the public: whenever the factory reached a certain production stage, if the wind blew at that moment, the strong smell of soy sauce was unbearable for nearby residents. Later, the factory was complained about to the environmental protection department. Thus, Zhou Zhijun became the "representative" for the residents who were constantly "perfumed" by soy sauce. "Actually, when you cook at home, you might find the smell of soy sauce quite fragrant, but after smelling it for a long time, it might make you feel uncomfortable. This kind of smell that makes citizens feel uncomfortable is what we need to monitor as foul odors," said Engineer Zhou.
After bringing toolboxes to the scene, Zhou Zhijun first needed to understand the production process, technology used, and gas emission situation of the soy sauce factory. To accurately grasp the situation, they also personally experienced it at the complainant's home. Only after fully understanding these situations could they formulate an odor sampling plan.
Collecting foul odors took half a day of squatting
After the plan was determined, the staff went to the boundary point of the soy sauce factory, waiting downwind. When a gust of wind came, and it was confirmed that this was the most pungent gas during the waiting period, the staff took out the pre-prepared vacuum bottle, opened the lid, and the foul gas was collected in the bottle. However, to ensure accurate sampling, one bottle of gas wasn't enough; they still had to continue waiting for the next wave of foul odor. Each sampling required a minimum of 3 to 4 bottles of gas samples, and the entire process usually took 6 to 8 hours to complete.
After bringing the sample gas back and smelling it, the soy sauce factory was ultimately judged by the odor evaluators to have exceeded the odor standard. After Engineer Zhou provided feedback to the relevant departments, the soy sauce factory was ordered to rectify. However, after some time, complaints about the soy sauce factory resurfaced. Upon re-investigation, it turned out that their rectification did not meet the standards and did not satisfy the surrounding residents. This time, the soy sauce factory was ordered to relocate. Then it was the turn of the soy sauce factory to cry injustice: "Clearly, my soy sauce factory was here first, and the residential buildings came later. We were fine before, so why do we have to relocate now?" Engineer Zhou said: "The requirements for industrial zones and residential areas are different. Now that it has become a residential area, from the perspective of putting people first, this soy sauce factory can only relocate due to 'exceeding the odor standard.'"
Zhou Zhijun told reporters that generally speaking, complaints in suburban areas mainly focus on food processing plants, petrochemical plants, etc., while complaints in urban areas concentrate on the catering industry. They once handled a citizen's complaint about a Sichuan restaurant. The spicy and numbing flavors of Sichuan cuisine were intolerable for Guangzhou natives who prefer light flavors, and at such times, the odor evaluators needed to step in to make judgments—whose fault it was. However, for such clearly targeted complaints, collecting sample air was much easier.
According to Director Wang, since there are currently not many units capable of completing odor intensity monitoring, the "noses" from Guangzhou Environmental Monitoring Station are often invited to other regions to act as "judges."
Dozens of "noses" ready to act at any time
On an afternoon before May Day this year, reporters visited the Guangzhou Environmental Monitoring Center Station and met the head of the "noses"—Deputy Director Wang Yujun and Deputy Director Huang Zhuo'er of the City Environmental Monitoring Station, listening to their stories about the "noses."
Wang Yujun told reporters that currently, over 30 "noses" at the Guangzhou Environmental Monitoring Station have obtained qualification certificates and can convict odorous gases. The Guangzhou Environmental Monitoring Station is also the first unit in Guangdong with the qualifications to conduct foul odor detection, starting this work around 2001. Additionally, the Panyu District Environmental Monitoring Station currently has over a dozen odor evaluators, and the sanitation department has gradually started this work.
Besides following the requirements of relevant departments to detect the odor concentration of landfills and sewage treatment plants every quarter, the "noses" are also responsible for handling citizen complaints. "With the continuous enhancement of citizens' environmental awareness, complaints about odors in living environments are also increasing," Engineer Zhou, who has been an odor evaluator for five years, told Information Times reporters.
It is understood that since 2009, the "noses" of the City Environmental Monitoring Station have already "adjudicated" over a dozen odor complaints. The power of the odor evaluators is significant—they can identify odors emitted by factories, enterprises, public toilets, rivers, catering establishments, or any fixed location. When citizens complain about strange odors in their surroundings, the "noses" must act.
How are odor evaluators trained?
Noses too sensitive may fail the exam
Odor evaluators are generally between 18 and 45 years old, both men and women are eligible, they cannot drink alcohol, have no olfactory diseases, and need to pass an olfactory examination. After training, they can accurately identify various "unpleasant" odors to humans and evaluate them through measuring odor concentrations.
Odor evaluators must pass exams to work—"it's not just finding a few people to smell randomly; only the results of certified odor evaluators are valid." Deputy Director Huang Zhuo'er told reporters.
Zhou Zhijun told reporters that when he first started working at the environmental monitoring station, he apprenticed for a while. Later, when an opportunity arose, he was recommended by his unit to take the odor evaluator exam. At the time, according to relevant regulations, the leaders of the monitoring station screened dozens of people from hundreds of employees across the station, and even then, only half passed.
Zhou Zhijun recalled that during the test, they were required to identify five types of single gases: floral fragrance, body odor, sweet potbelly aroma, ripe fruit fragrance, and fecal odor. "But these smells were synthesized using chemical components, with extremely low concentrations." He told reporters that if your nose had even a slight issue, you wouldn't be able to identify them.
Reporters also learned that although the work of odor evaluators has high requirements, it does not require an exceptionally sensitive nose. "Hearing this name, you might think our sense of smell is extraordinary, but actually, we represent the noses of the general public. During the olfactory test for selecting odor evaluators, you must pass our standard olfactory determination. If your sense of smell is insufficiently sensitive or overly sensitive, you won't qualify. If overly sensitive, for those being monitored, others might not smell it but you do, which wouldn't count as pollution," an odor evaluator told Information Times reporters.
Because people's sense of smell varies, they sometimes receive complaints where, after mobilizing significant resources, it turns out that the subject of the complaint does not emit odorous gases exceeding standards. "We understand this situation; some people have particularly sensitive noses, and smells that others don't find uncomfortable might be unbearable to them alone. In such cases, we can only rely on the results of the odor evaluators. If the results show no exceedance, we can only work with the complainants."
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