Definition
Inspiration
COVID-19 infection recurres in the post-epidemic era and lung function is impacted after infection. Smoke in enclosed corridors, the pungent stench in public toilets and the odour emanating from rubbish dumps can make us more sensitive and discomfortable, as well as cause long-term hazards: indoles in excreta can affect the human nervous system, leading to neuron deaths and episodes of neurodegenerative diseases. As a class 1 carcinogen, formaldehyde contained in chambers and second-hand smoke is a major respiratory hazard for human beings.
It has come to our attention that there are no specific air purifiers available in these situations. Private and personal areas such as bedrooms, classrooms, and offices are where air purifiers are installed, but in some communal and everyday scenes, the smell of smoke and odour is ignored. We began to consider using biotechnology to eliminate harmful gases in the environments of life.
Our Values and Design
Our team has been upholding the practical and realistic value: we go into different public scenes in daily life, interview different scene participants, so as to identify the public scenes and specific pollutants that need to be air-purified.
In addition, we also adhere to the scientific and responsible value, promising not to cause new trouble for the sake of solving the problem, and proposing solution paths in a safe, environmentally friendly, and economical way. On the basis of these values, we have developed a human practice design, which includes 4 steps: understand the problem, scene research, project design, application evaluation.
Understand the Problem
Zhang Qin
Associate Professor, West China School of Public Health, Sichuan University, specialising in public health related to environmental health.
Wan Yue
Researcher I, Department of Regulations and Standards, Ministry of Ecology and Environment, China.
Goal: Gas pollution is complex and varied. In order to identify the pollutants that are of most concern to the public, we decided to consult with environmental experts and investigators before starting the research.
Communication:
- The national ecological investigators first introduced the selection of national standard pollutants. The selection of pollutants is a multidisciplinary and comprehensive process, In addition to the internationally recognized basic air pollutants, the investigators are tasked with carrying out technical monitoring of one of the pollutant gases under a specific scene, and then analyzing its yield and toxicity.
- They suggested referring to national indicators and relevant literature to select relevant substances based on their harmfulness and universality. As impaired lung function is a universal phenomenon, daily life scenes can be seen as research scenes to identify prevalent pollutant gases in some specific scenes.
- They expressed doubts about the purification of second-hand smoke.With the anti-smoking policy in public places and the increase of citizens' awareness of anti-smoking, the investigation of second-hand smoke needs to go into the public and actually understand their views.
- They reminded us not to innovate for the sake of innovation, but to find out if there are simpler ways, such as increasing the power of exhaust fans or opening windows for ventilation.
Achievement: With the advice of the two experts, we aimed at conducting in-depth research in everyday scenes to understand the public's dynamic perceptions and deodorization measures. Needs of society, the hazards of gases, and policy directions count.
Scene Research
Reaching out to those affected is the most effective way to understand air pollution, as we believe. However, it is difficult to obtain the names of specific pollutants directly from people, since not everyone is a scientist. The general public may not have the necessary scientific knowledge. Our initial measure was to use public scenes to identify the most prevalent and harmful pollutants. It's also crucial to compare the existing solutions with the air purifiers approach.
Odour
The first object of our research was the odour of excrement, and we categorized the different scenes as animal scenes (scenes with a concentration of pets), daily use scenes (public toilets) and industrial scenes (sewage plants). We wanted to find out how well their current deodorization measures dealt with excreta odour.
Pet Scene:
We visited pet-concentrated scenes and collected owners' deodorisation measures and effectiveness. We believe that existing deodorisation measures in commercial premises are time-consuming, labour-intensive and incomplete in terms of smell, or extremely costly, and can be afforded by very few people. We do not believe that the above measures are a substitute for air purifiers.
Degree | Characteristics | Cleaning | Flaws |
Unbearable | Extreme stinky | Do nothing | No effect |
Tolerable | Stinky around the cage | Open windows Clean timely | Time-consuming and energy-consuming |
Comfortable | No odour | Installing air system | Noisy High cost for purchase |
We made available 200 online questionnaires. We were surprised to learn that approximately 50% of owners were interested in upgrading their deodorant supplies or basic deodorant tools. The market for pet deodorization represents prosperity.
Public Toilets
We had a conversation with a cleaning lady who has been cleaning scchool toilets for a considerable amount of time. In general, public toilets rely on exhaust fans and diligent cleaning to remove odour, as she told us. The morality and quantity of people are also significant factors. Asked about the worst time, she replied that the worst time of the day is in the morning, when the exhaust fans are switched off at night; the worst time of the year is in the summer, when Chengdu's high temperatures and high humidity amplify the stench of excrement. According to the students who came to the toilet, there was a large number of people in the toilets during break time. The exhaust fan's power could not keep up with the strong odour, so the odour was often unbearable.
What we have learned: public toilet deodorisation is affected by the design of the environment, the flow of people, the quality of the user, the time period and the temperature. While household toilets can increase the power of the exhaust fan to deodorise, many factors affect the concentration of stench in public toilets. So it is difficult for the exhaust fan to be flexibly adjusted to suit the need for purified air to remove stench..
Sewage Plant
Our team visited Chengdu No. 9 Water Sewage Plant. The technicians told us that there are many anaerobic processes used in China to treat wastewater from livestock and poultry farms, among which the more commonly used ones are anaerobic filters (AFs), upflow anaerobic sludge beds (UASBs), composite anaerobic reactors (UASBs + AFs), two-stage anaerobic digestion, and rising sludge bed reactors (USRs). The sewage plant has a mature technological system. Despite this, the disadvantages are the high energy demand, high infrastructure requirements, and high operating costs. Our project utilizes microbial degradation, which saves energy, has low maintenance costs, and is highly sustainable, making it a good match for existing technologies.
Formaldehyde
With the policy makers intensifying control of formaldehyde, the problem of excessive formaldehyde in decoration and building materials has been greatly reduced, so we questioned the necessity of formaldehyde removal air purifiers. This situation reminds us of haze air purifiers. Sales of haze air purifiers increased in 2013 due to the concentrated haze. Years later, with the success of the haze control, most of these purifiers are sitting idle. Our research began to explore the similarities between the two situations.
We learn that pollution in cars is one of the major sources of formaldehyde. Car owners believe formaldehyde will be released in a few months after purchasing a new car, so we used professional measuring instruments to verify the scientific validity of this claim. We chose to test a car purchased a year ago in 32-degree weather, which was fitted with a large amount of leather upholstery and was largely free of new car odours.
The outdoor air quality formaldehyde concentration was 0.01mg/m during the test. The car's initial concentration of formaldehyde was 0.07mg/m. After 30 minutes of exposure to the sun, the indicator rose to 0.19mg/m, far more than the safety standard of 0.08mg/m. The experiment proves that formaldehyde removal is slow and volatilization is unstable. In order to ensure that the car occupants enjoy safe air, people would better purchase an air purifier that removes rotenone formaldehyde.
Non-smoking Areas
Sichuan province, in the southwestern part of China, has a smoking rate of 29.4% for residents over 18 years old. Secondhand smoke exposure rates of non-smokers are 67.52%, which is the most common factor in the development of lung cancer. In recent years, Sichuan has implemented corresponding policies to control second-hand smoke in public places. Unfortunately, second-hand smoke in public places has not completely disappeared, so we initiated a social survey.
The scenes are categorized based on strictness of the anti-smoking policy and the willingness to smoke as variable references. The scene constraints are related to whether the scene has anti-smoking policy and the strength of its implementation. The personal willingness is related to the frequency of personal smoking. Thus, we classify three types of scenes:
- Scenes with loose constrains and strong willingness to smoke: pubs, internet cafes, and restaurants.
- Scenes with strict constrains but strong willingness to smoke: flat corridors, non-smoking office corridors, fire escapes.
- Scenes with strict constrains and weak willingness to smoke: no smoking areas, hospitals, kindergartens.
*There is no scene in which smoking intentions are low in a loosely constrained environment, so this scene is not included in the study.
Service Industry Scene
The management of no-smoking in service establishments is lagging behind, as we have observed. Even though indoor smoking is prohibited by the State, the management of no-smoking in the service industry industry is not strictly enforced. It may be considered a normal phenomenon by some operators. Achieving a total ban on smoking may still be decades away, and promoting anti-smoking awareness has a long way to go. Second-hand smoke air purifiers are effective to protect people from the harms of second-hand smoke during this time.
Corridor Access
A strict no-smoking policy can restrict smokers' behavior to a certain extent, but it doesn't refrain them from smoking. Smokers will sneak outside, addicted to smoking in corridors or fire escapes. We identify these areas as "grey zones". These are areas with high traffic that do not comply with the no-smoking policy's requirement for second-hand smoke.
Comprehensive Smoking Ban Places
Unlike the loopholes mentioned earlier in public area management, second-hand smoke in these scenes is harmful and the effects are visible quickly. The control of public areas, such as kindergartens and children's hospitals outside, is more rigorous. People's resistance to second-hand smoke is weak and it causes discomfort instantly, so smoking is prohibited both indoors and outdoors.
In summary, we have decided to define second-hand smoke use scenes in places with strong willingness,including service industry scenes and grey areas. We believe that installation of air purifiers can guard the health of the non-smoking community until smoke-free public places are truly achieved.
Project Design
Selected Pollutants
We conducted extensive literature reading on second-hand smoke, excreta odour and domestic waste odour gas. Nicotine, tar and formaldehyde in second-hand smoke are the most hazardous to human body: nicotine can make people addicted as the most dangerous chemical substance in tobacco; tar contains benzo[a]pyrene which is a class 1 carcinogen stipulated by WHO. Benzo[a]pyrene concentration in the indoor air of the family with addicted smokers is 10 times more than that of the family without smokers[1]; formaldehyde is irritating and may even cause leukaemia[2]. What's more, ammonia, hydrogen sulphide, indole and butyric acid account for a large proportion of the concentration of odourous gases. They are widespread and emit unbearable odour.
Our targeted pollutants also respond to the national policy. In China Indoor Pollution Indicators (CIPI)[3], the state regulates prevailing and hazardous pollutants, and our choice of ammonia, formaldehyde and benzo(a)pyrene are among them.
| Indiacators | Measuring Unit | Requirement | Remark |
| Ozone (O3) | mg/m³ | ≤0.16 | per hour |
| Nitrogen dioxide(NO2) | mg/m³ | ≤0.20 | per hour |
| Sulfur dioxide (SO2) | mg/m³ | ≤0.50 | per hour |
| Carbon dioxide(CO2) | %² | ≤0.10 | per hour |
| Carbon monoxide(CO) | mg/m³ | ≤10 | per hour |
| Spandex(NH3) | mg/m³ | ≤0.20 | per hour |
| Formaldehyde (HCHO) | mg/m³ | ≤0.08 | per hour |
| Benzene(C6H6) | mg/m³ | ≤0.03 | per hour |
| Methylbenzene(C7H8) | mg/m³ | ≤0.20 | per hour |
| Xylenes(C8H10) | mg/m³ | ≤0.20 | per hour |
| TVOC | mg/m³ | ≤0.60 | per 8 hours |
| Trichloroethylene(C2HCl3) | mg/m³ | ≤0.006 | per 8 hours |
| Tetrachloroethene(C2HC4) | mg/m³ | ≤0.12 | per 8 hours |
| Benzopyrene(BaP) | ng/m³ | ≤1.0 | per 24 hours |
| Inhalable particles(PM10) | mg/m³ | ≤0.10 | per 24 hours |
| 2.5-micrometer Particulate Matter(PM2.5) | mg/m³ | ≤0.05 | per 24 hours |
Application Evaluation
Commercial
In order to understand the application prospects of our biological air purifiers, we have researched the existing air purifier market.
Yuan Yuyang
Director of Public System Service Department, Yibai Pharmaceutical, one of China's top 100 pharmaceutical companies.
Goal: The company is orientated towards the users of air purifiers. They know more about the needs of the users and the shortcomings of the existing air purifiers. Useful information can be obtained from them.
Communication:
- Our project was welcomed by Director Yuan. He introduced the effective technology of air purifier in the market. HEPA technology enables air purifiers to remove suspended particles at a 99% rate.
- He stated that the majority of air purifiers currently on the market utilize physical and chemical technologies, and that biotechnology is a new concept with potential value.
- When talking about the shortcomings of the existing technology, he pointed out that the activated carbon cartridge is widely used to adsorb harmful gases, but it is likely to cause secondary pollution. Once the activated carbon adsorption becomes saturated, the pollutants in the activated carbon cavities are likely to come back to the air. The activated carbon cartridges are expensive and not environmentally friendly, and the biotechnology can be a good way to overcome this problem.
Achievement: We have learnt that existing air purifiers are strong in removing particulate pollutants, yet the activated carbon used to remove gaseous pollutants still faces the disadvantages of secondary pollution and poor sustainability.
Jiang Jianchun
Academician, Director of the National Engineering Research Centre for Forest Chemicals.
Sun Kang
Researcher, Director of Activated Carbon Research Department, Institute of Forest Chemical Industry, Chinese Academy of Forestry.
Goal: We have already comprehended the shortcomings of activated carbon filters. In order to understand the efficacy of activated carbon in absorbing the odour of second-hand smoke and fecal gas, we visited the Institute of Forestry and Chemical Industry of the Chinese Academy of Forestry. The institution is the main developer of the National Standard for Indoor Purification of Activated Carbon, LY/T 3012-2018 "Activated Carbon for Indoor Air Purification".
Communication:
- The saturation of activated carbon can be significantly different in different situations, because the adsorption rate of activated carbon on harmful gases is affected by multiple factors such as pore size, adsorption and adsorbent.
- Monitoring secondary pollution is a challenge for household air purifiers. Smaller air purifiers currently do not have on-line monitoring devices to determine the pole of saturation of activated carbon adsorption. They are in agreement that biological cartridges have advantages over traditional activated carbon cartridges if they are efficient and safe.
- They believe that future air purifiers can start in the direction of "activated carbon adsorption + biodegradation", focusing on degradation. As long as there are reliable data that support the effect of biodegradation, it can be explained well. Biodegradation can also make up for the effectiveness, economy, and environmental protection that activated carbon adsorption cannot meet.
Achievement: Secondary pollution is a risk and the traditional activated carbon cartridge is unstable. In contrast, the biodegradation of biofilter is thorough, which can prevent secondary pollution at the root, and avoid the replacement of activated carbon cartridges, which are environmentally friendly. In terms of effectiveness and sustainability, air purifiers based on biological technology win out.
Political
Our reference is to the National Standard for Air Purifier GB/T 18801-2022[4]. The paper stipulates that the coverage of harmful gases is very limited. Second-hand smoke and fecal odour are common air pollutants. The standard lacks much of the main harmful gases, and the objects of concern to us, such as nicotine and hydrogen sulphide, are not included. We inquired with the compiler of the National Standard.
| Target Pollutant | Occurrence Method | Detection Method |
| TVOC | a). Gaseous pollutants at room temperature and pressure with analytically pure or higher grade reagents (e.g., toluene, formaldehyde, ammonia, etc.) can be generated using equipment that generates gaseous pollutants with high purity and efficiency. b). Gaseous pollutants have standard gases (such as sulfur dioxide, nitrogen dioxide, ammonia, etc.) can choose the appropriate volume concentration of the standard gas cylinders generated directly | See methods in GB/T 18883, GB/T 18204.2Z or online instrumental methods |
| Benzene | ||
| Methylbenzene | ||
| Styrene | ||
| n-Butyl acetate | ||
| Formaldehyde | ||
| Ozone | ||
| Spandex | ||
| Nitrogen dioxide | ||
| Sulfur dioxide |
Xie Xiaobao
the developer of Air purifier National Standard, China Quality Inspection Association air purification equipment professional committee experts.
Ran Hongyu
Chairman of the Board of Directors of Beyondsoft, the developer of the National Standard for Air Purifiers.
Goal: The pollutants covered by the National Standard for Air Purifiers do not include the main harmful substances we are concerned about in second-hand smoke, excrement odour and rubbish odour, though common in our lives but are not covered by the National Standard. It's necessary to uncover the reasons behind this.
Communication:
- The two experts said that the standard mainly regulate the performance indicators of products on the market according to their application scenes. Our air purifiers are mainly used in the living room, bedroom, for formaldehyde, benzene, ammonia, and other decorative materials produced by harmful gases to purify the treatment. Ammonia is the most prevalent odor gas in the washroom.
- Gaseous pollutants should indeed be a concern, but will only be gradually incorporated into the National Standard once many purifiers on the market start claiming these features and there are mature and simple testing methods.
- Products in the research and development period are not necessarily covered by the standard. National standards are generally lagging behind, and enterprise standards or group standards can be developed first.
Achievement: We have learnt that national standards are often lagging behind as they are formulated according to market demand. Nowadays, air purifiers are mainly used in bedrooms and living rooms, but less in public scenes. The pollutants we mentioned are less involved in domestic scenes. Only when the public attaches importance to the cleanliness of air in public scenes and the demand for public field air purifiers rises, will the National Standard include the substances we have studied. But until then, we may design our own standards for use on a small scale.
