Introduction

Indoor and outdoor pollutants have significant impact on human health. According to data presented by the World Health Organization (WHO), 6.7 million death occurs as the result of ambient air pollutants. Moreover, 99% of global population is exposed to concentration of pollutants above the WHO limits (World Health Organization 2023).

Many nations worldwide are obliged to develop safeguarding policy actions towards cleaner air which are targeted to protect human health, biodiversity and ecosystems. Most of the actions are the result of international agreements aiming at the mitigation of atmosphere pollution effects and adaptation for climate change (European Commission 2009). Through the enhancement of air quality and the reduction of human exposure to pollution, numerous diseases can be prevented, particularly among children and the elderly who are highly susceptible to the harmful effects of particulate matter (PM). First of all, reducing pollutant emissions is a method to achieve improvements in air quality. A possible way to improve local quality of air related to households, especially in rural areas, is to shift towards clean energy sources in such utilities, avoiding or limiting the emission of particulate matter (Shen et al. 2022). Consequently, long-term environmental measures have been mandated by international agreements to eliminate the release of pollutants into the atmosphere. In addition, short-term interventions are also recommended, such as one-off actions with immediate results, like air purifiers.

Most of the conducted research refers to the devices available for mitigating indoor air pollutants within buildings (Yue et al. 2021). For a good well-being, a person should spend as much time as possible outdoors (White et al. 2019). This applies especially to children and the elderly, who often stay in schools, sanatoriums, hospitals and daycares (Caldwell et al. 2014). The air quality in early spring, late autumn and winter are often very poor in several areas worldwide. For instance, Poland is a leader in air quality issues, with PM10 levels exceeding EU directive standards several times, and permissible limits from the WHO recommendations several dozen times (Styszko et al. 2015, 2016; Szramowiat et al. 2016; Samek et al. 2017). Therefore, this paper focuses on providing a device to address the burden of outdoor air pollution on vulnerable populations such as children and the elderly by installing an air purifier in outdoor spaces they regularly occupy. Purifying the ambient air would contribute to reducing the percentage of contaminated air entering indoor spaces. To lower the concentration of ambient air pollutants, various approaches have been employed so far, such as the utilization of synthetic coatings that rely on surface sorption phenomena, air-moving towers and filtering towers (Cyranoski 2018; Burki 2019). Another concept is urban forests, green spaces composed of trees, shrubs and other vegetation within urban areas which play a crucial role in improving air quality by adsorbing pollutants such as carbon dioxide, sulphur dioxide, nitrogen oxides, ozone and particulate matter. Despite this, the sorption capacity of urban forests is ineffective during periods of severe air pollution resulting from adverse meteorological conditions (Hirabayashi 2021). Addressing this issue, the synthetic SUNSPACE coating (Zanoletti et al. 2018) utilizes surface sorption phenomena and can be applied to various surfaces like roofs, walls and roads. Another solution applicable to multiple surfaces is airlite paint, which purifies air through the photocatalytic oxidation effect of titanium dioxide (AM TECHNOLOGY LIMITED 2018). Both the SUNSPACE coating and airlite paint are passive methods designed to consistently reduce PM concentrations, albeit with low efficiency requiring extensive surface coverage for noticeable results, making them costly and insufficient during periods of high pollutant concentrations. In addition to passive methods, active air purification methods exist.

U-Earth’s air purifiers, based on developed bioreactors like U-Ox, feature a population of non-genetically modified bacteria capable of cleaning the air from PM, allergens, bacteria, odours, viruses and chemical fumes (2024a). The Smog Free Tower, standing 7 m tall, cleans 30,000 m3 of air per h using patented positive ionization technology, deployed in South Korea, China, the Netherlands and Poland (2024b). Purevento GmbH developed the City Air Cleaner, available in different models such as S6 (cleaning up to 60,000 m3 of air per hour) and M-20 (cleaning up to 20,000 m3 of air per hour) (2024c). Another viable large-scale solution involves the implementation of a shock wave generator, which emits sound waves to disrupt the inversion temperature layer and facilitate the restoration of natural convection (Jędrzejek et al. 2021). These active methods effectively clean the air in close proximity to the devices but require connection to the electricity network, posing a significant expense (Laxmipriya et al. 2018). They demand huge infrastructure and generate high operational costs.

The intention of the authors was to develop a device which could be utilized in micro-locations (relatively closed outside spaces) and to place it in a central point, which would reduce air pollution. Here, we present a novel approach to ambient air purification utilizing renewable energy sources and achieving self-sufficiency in energy consumption. Moreover, recycled polymer materials have been applied making the air purifier environmentally friendly. This technology eliminates the need for an electric grid, making it adaptable to any location. The aim of the paper was to study the sensitivity of the air purifier and its efficiency in particulate matter and its components removal.

Study design

Technical parameters of the air purifier

The air purifier (AP) has been designed in the form of a bollard, measuring 900 × 900 × 1800 mm. It comprises several components, including a fan, cyclone and electrostatic filters, solar panels and energy management and storage systems. The fan has the capability to process a polluted air stream at a rate of 400 m3/h. The initial stage cyclone filter is a passive filter that operates by utilizing centrifugal force to separate dust particles from the air as it passes through the device. The specific dimensions of the filter can be found in Table 1. The used cyclone was characterized by a cyclone diameter of 250 mm for the cylindric section, while the whole cyclone geometry has been designed on the basis of an internal diameter of the air outlet of 100 mm. This diameter has been selected in order to achieve an effective filtering of air for particles with a diameter of 10 μm and bigger.

Table 1 Construction details of cyclones
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Another component is the electrostatic filter, which plays a crucial role in thoroughly purifying the air. This filter consists of a series of mesh nets with a wire diameter of 25 mm and a cell size of 0.4 × 0.4 mm. To power the electrostatic filter, a high voltage generator (HV generator) has been developed, operating within a voltage range of 5–25 kV. The bollards are powered by polycrystalline PV panels with a total capacity of 600 W. Energy storage is achieved through a configuration of interconnected Samsung INR18650-35E lithium-ion cells, organized in both series and parallel connections. The battery stack can support a load of up to 160 W and has a capacity of 10,000 mA h. To promote sustainability, recycled polymer materials have been utilized in the construction of various bollard elements, including the cyclone filter, ventilation ducts and the bollard casing (Fig. 1).

Fig. 1
figure 1

The scheme of air purification system

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The description of the experimental stage

The experimental setup involved a combined cyclone and electrostatic precipitator installation, constituting a collaborative system aimed at achieving comprehensive air purification. To ensure optimal airflow throughout the system, an exhaust fan was utilized to induce air movement, with the ability to modulate power across the entire range. The airflow was carefully monitored and controlled using various measuring devices such as thermoanemometers and differential pressure sensors. Thermoanemometers were employed to measure the velocity of air flow within the system and establish the optimal airflow settings. On the other hand, differential pressure sensors were responsible for detecting any excessive backpressure, thus preventing sudden drops in pressure and potential filter overload due to excessive dust accumulation.

Gravimetric measurement of particulate matter removal efficiency

Two similar gravimetric PM sampling systems were used for simultaneous PM samples collection at the inlet and outlet of the air purifier in order to assess the air purifier efficacy in particulate matter removal. The sampling probes of the gravimetric PM samplers were positioned in such a way that the air intake point aligned with the channels of the filtering device. The sampled air passed through a quartz filter where total suspended particles (TSPs) fraction of particulate matter was deposited. The process of sampling was conducted isokinetically. The first measuring probe was positioned at the inlet to the AP—behind the system for hyper-polluted air generation. The second measuring probe was positioned ca. 50 cm behind the electrostatic filter. By comparing the amount of dust present at the inlet and outlet of the filtering device, the efficiency of its operation was determined.

Each PM sampler was equipped with dedicated air pumps, measuring probes with quartz fibre filter holders, plastic hoses and other auxiliary equipment such as batteries and flow meters. The samples of TSP were collected on Whatman® QM-A quartz filters. These filters had a porosity of 2.2 µm and a thickness of 450 µm. The maximum air flow rate through the filters was measured at 0.99 s/100 ml/cm2. With a temperature resistance of up to 500 °C, the filters were non-sterile and required appropriate pre-treatment prior to testing. To prepare the filters, they were heated at 550 °C for 5 h, followed by transfer to a desiccator with water for approximately 2 h. Subsequently, the filters were stored in a chamber with constant temperature (20 ± 2 °C) and relative humidity (50 ± 5%) conditions for 24 h. The PM mass was determined through gravimetric measurements by calculating the difference between the average masses of three consecutive weights after and before the collection of the dust sample on each filter.

For the purposes of the research, the hyper-polluted air was generated in exhaust generation system equipped with a built-up grate and an exhaust tract with needed instrumentation. The system for exhaust generation was previously designed for the purposes of combustion-related exhaust testing. The hyper-polluted air was forced in order to simulate the real outdoor conditions with episodes of highly elevated concentrations of pollutants in ambient air which frequently occur in Poland, especially during heating seasons. The hyper-polluted air simulates pollution primarily derived from combustion processes. In order to generate polluted air, approximately 500 g of mix of materials (fuels and wastes) was combusted during each iteration of experiment repetitions and TSP samples collection. One TSP fraction sample was collected in time fractions: from the start of hyper-polluted air generation to the end. The quartz fibre filter was then transferred from the filter holder to a plastic Petri dish, and the new quartz fibre filter was placed in a filter holder of gravimetric PM sampler, afterwards. Each iteration of the entire experiment took ca. 45 min and was repeated several times in order to gather enough material for further laboratory analysis. After each sampling, the experiment stage was pre-cleaned and purged by clean air using the fan for ca. 10–15 min. Once pre-cleaning and purging are finished, the next iteration of sampling process could start again. The conditions of the experiment were maintained constant and isokinetic during each iteration in order to ensure the repeatability of obtained results. The collected TSP samples underwent further laboratory analysis for the presence of elemental and organic carbon and other inorganic PM-bound chemicals. As the conditions of sampling were constant and repeatable, the discussion of section “Results and discussion" refers to average out of all conducted tests.

Determination of the content of PM-bound chemicals

In order to better characterize the performance of the air cleaner, the impact of multiple contaminants was investigated. Hence, PM samples were analytically treated in order to determine the content of PM-bound components such as: carbonaceous compounds, inorganic ions, metalloids and metals, including heavy metals.

Sunset Laboratory Inc. OC/EC Analyser based on the thermo-optical method developed for atmospheric samples was used to determine the content of organic (OC) and elemental carbon (EC) in the suspended dust. The quartz.par or eusaar2.par analysis protocol was used. The method was previously described in Szramowiat et al. (2016), Górka et al. (2020) and Buch et al. (2021). The relative standard deviation was 5%.

The isocratic ion chromatography technique was used to determine the concentration of the following inorganic cations and anions: Li+, Na+, K+, Mg2+, Ca2+, NH4+, F−, Br−, NO2−, NO3−, Cl−, PO43− and SO42−. To extract the anions from PM, a punch (ø 8 mm) cut from the quartz filter was placed in a plastic test tube in 1.5 ml of deionized water. The tube was then placed in an ultrasonic bath for 20 min. The cations were similarly extracted into 1.5 ml of a 12 mmol metasulfonic acid solution (MSA). Ion chromatograph (ICS-1100, Thermo Scientific) equipped with AS-DV autosampler and ion exchange column was used to determine the content of inorganic cations and anions. For the anions, an Ion Pac AS22 column (4 × 250 mm) with 4.5 mM Na2CO3 + 1.4 mM NaHCO3 mobile phase and an AERS 500 suppressor (4 mm) was used. The determinations were made in the presence of a mixture of Na2CO3 and NaHCO3 as the eluent. For the cations, an Ion Pac CS16 column (5 × 250 mm) with a 48mM MSA mobile phase and a CDRS 600 suppressor (4 mm) was used. The determinations were performed in the presence of MSA acid as the eluent (48 mmol). The quantitative analysis was possible thanks to the presence of a conductometric detector. The details of the analytical method and detections limits were previously described by Szramowiat-Sala et al. (2019) and Pacura et al. (2022).

The elemental analysis was performed using a Rigaku ZSX Primus IV X-ray fluorescence wave dispersion spectrometer (WD-XRF). The system uses a family lamp with a power of 4 kW, equipped with a window with a thickness of 30 microns with a maximum accelerating voltage of 60 kV and a maximum current of 150 mA. The signal was collected from an area of 3.14 cm2, and the sample was rotated at 30 rpm during the experiments. Semi-quantitative (SQX) analysis was performed with the ZSX software. The percentage mass content of B, C, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, Ni, Cu, Zn and Zr was determined.

Data analysis

Data analysis and statistical tests were conducted using Ms Excel and Statistica 13.3. Paired t-test was carried out to observe the difference in mass concentration of PM and PM-bound components after the operation of the air purifier during each sampling scenario. Statistical significance was a 5% level (P < 0.05). The differences in mass concentration of PM and PM components were calculated by dividing the differenced concentration by their initial mass concentration and further multiplying the resultant with 100.

Results

In this section, there are presented the results of the study on the effectiveness of environmentally friendly and energy-self-sufficiency-based air purifier in filtrating of PM and its components. The differences in AP sensitivity to inorganic and organic fractions are discussed. Through a comprehensive discussion, we explore practical implications of our findings and also their limitations.

Air purifier removal efficacy on PM and PM-bound carbonaceous compounds

The simultaneous gravimetric measurements of particulate matter both at the inlet to and at the outlet of the air purifier allowed to observe the significant depletion (confirmed by a t-paired test, P value = 0.02) of particulate matter mass in the stream of polluted and filtrated air. The mass of PM decreased from 26.2 mg at the inlet to 6.9 mg at the outlet, which gave the percentage difference at the level of 74.1% (Fig. 2a). PM-bound carbonaceous compounds, which stand for elemental and organic carbon in summary, exhibited the decreasing trend through filtration as well. The mass of organic carbon depleted by 13.8% and elemental carbon 32.9%. However, this percentage differences were not statistically significant. The total share of total carbon in particulate matter mass increased from 24.8% of PM mass at AP inlet to 82.3% of PM mass at AP outlet. Organic carbon mass shared similar fraction of total carbon both at the inlet and outlet to AP, accounting for 95.0 and 93.8%, respectively. The stable share of EC and OC in total carbon fraction may indicate to higher sensitivity of AP to non-carbonate chemicals or inorganic carbonate structures. This is explored further in Sect. "Air purifier removal efficacy on inorganic ions" and "Efficiency of metal and metalloid removal by the air purifier".

Fig. 2
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Mass of PM and PM components measured at the inlet (AP_IN) and the outlet (AP_OUT) of the air purifier and computed percentage difference of PM and PM components: a PM and carbonaceous compounds, b anions, c cations and d elements

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Air purifier removal efficacy on inorganic ions

Anions accounted only for 1.5% of total mass of particulate matter measured at the inlet to air purifier. No significant change was observed, as at the outlet from air purifier anions mass accounted for 1.17% of PM mass. Nevertheless, filtration process influenced the removal of anions. Their mass depleted from 419.8 µg at the inlet to 45.1 µg at the outlet, which gave a statistically significant 89.2% difference (P value = 0.029). The highest concentration was observed for sulphates (SO42−) which accounted for 273.4 µg in PM in entering to the AP air streamline (Fig. 2b). The trend of other ions at the inlet was as following: F− > Cl− > Br− > PO43− > NO3−. At AP outlet, the highest value was reported for F− (15.0  µg) which a mass trend of other ions measured at AP outlet as following: Cl− > PO43− > Br− > SO42− > NO3−. The removal of sulphates was the most effective (99.1%). For phosphates, chlorides, fluorides and bromides, the percentage difference varied between 48.9 and 88.6%. Only for sulphates and bromides, these differences were significant with P vale equal to 0.046 for both according to t-paired test. Nitrates demonstrated a 25% increase in mass as a result of filtration. This can be rather attributed to analytical method errors and be the effect of sample treatment processes.

While the hyper-polluted air was filtrated the cation summarized mass depleted from 809.6 µg at AP inlet to 31.9 at AP outlet. This slightly over 96% difference was significant, P value for t-paired test equalled 0.046. The cation mass share in PM also changed: at AP inlet cations altogether took 2.8% of PM mass, whereas at the inlet—1.45%.

Calcium ions (Ca2+) were the most prominent cation both at the inlet and outlet of the air purifier, counting for 660.7 µg and 27.5, respectively (Fig. 2c). The mass trend in the case of remaining cations measured at AP inlet was as following: Mg2+ > Na+ > K+ > NH4+ > Li+ and at AP outlet: Mg2+ > Na+ > NH4+ > K+ > Li+. The nearly full decrease of mass was observed for sodium > potassium > magnesium and calcium ions, whereas the masses of lithium and ammonia ions depleted by 83.0% and 49.0%, respectively. Among all these divagations, only Ca2+ percentage difference was statistically significant (0.043).

It seems to be obvious that during filtering, the chemical reactions may occur between components of airstream and on the surface of particulate matter as well. The ion equivalents were compared, and anion-to-cation (a/c) ratio was 0.38 at the inlet to air purifier (while a/c is close to 1 it means that ions are balanced). This points out to the significant excess of cations in the relation to anions. We need to remember that the content of carbonate anions was not analysed during the experiment, but their presence cannot be excluded. At AP outlet, the a/c equivalent ratio exceeded 2, pointing out to the excess of anions. One of the hypothesis can state that carbonate ions were not filtered sufficiently and this could be consisted with a statement mentioned in 3.1 Section and that the air purifier may demonstrate higher sensitivity of AP to non-carbonate chemicals. This should be examined further.

Efficiency of metal and metalloid removal by the air purifier

Among the identified elements, silicon, carbon and oxygen exhibited the highest values in both the PM samples collected at the inlet and outlet of the air purifying filter (Fig. 2d). The presence of silicon in combination with oxygen (SiO2) can be attributed to the quartz filter, which served as the collection substrate for the PM samples. The elevated response for carbon is expected, considering its predominant presence in the PM fraction. The elements with the highest mass values in the PM samples taken at the inlet of the tested filter were calcium, iron, aluminium and sulphur. On the other hand, behind the filter, the highest mass was recorded for potassium, chlorine, sulphur and calcium. Different elements demonstrated higher mass values at different stages of the filtration process, indicating changes in the composition and potential interactions between the PM and, possibly, the purifying filter. Certain elements such as potassium (K), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr) and ions including sodium (Na+) achieved a removal efficiency of almost 100%. However, it is important to note that the full removal of certain elements may be slightly lower in reality due to potential limitations in the sensitivity of the analytical method and treatment of PM samples with low mass values. Although the percentage difference between inlet and outlet masses of elements was significant 93.9% with P value = 0.005), the depletions in masses of most visible elements (S, Cl, K, Ca and Fe) were not statistically significant (P value exceeded 0.05).

Discussion

Table 2 provides a comparative analysis of percentage differences of PM and PM chemical fractions measured upstream and downstream of the air purifier. This comparison enabled an initial assessment of the filter’s effectiveness in removing impurities. A noticeable decrease in mass values was observed for all analysed groups of PM component. The overall effectiveness of PM mass filtering was measured at approximately 74.1%. In terms of PM-bound chemicals, the purification efficacy varied, with carbonaceous compounds exhibiting a removal efficiency of 14.2%.

Table 2 The effectiveness of the air purifier in filtering of PM and PM components
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The literature has mainly examined indoor air purifiers similar to the one proposed in this paper. However, comparing to other indoor interventions, it can be stated that the effectiveness of air purifier presented in this paper is relatively high or equal to other ones presented in literature both in the aspect of PM reduction and its chemical components. Dubey et al. (2021) assessed the effectiveness of HEPA filters for indoor particulate matter controlling. The effectiveness of two-step filtration using HEPA filters raised to 68% in PM mass reduction and to 99% in case of cations reduction. In Washington, portable air cleaners with HEPA filters were distributed in homeless shelters. This solution was an effective short-term strategy to reduce indoor particle levels in community congregate living settings during non-wildfire periods (Huang et al. 2023). A biological cleaning filter proposed by Yewale et al. (2022) may be a promising solution for controlling both indoor and outdoor particulate matter as well. The Biosmotrap filter is composed of sponge gourd and algae removed 70–90% of COx, NOx and PM2.5 from heavily polluted air. Fazlzadeh et al. (2022) investigated the health benefits of using an air purifier by its ability to decrease the concentration of polycyclic aromatic hydrocarbons (PAHs), heavy metals and ions bound with PM2.5. The results showed removal of 76.5%, 63.1% and 66.2% for PAHs, metals and ions, respectively. A similar reduction ratio (72.4%) was obtained by Pei et al. (2020) who conducted a long-term monitoring of portable air cleaners in China. Blondeau et al. (2021) tested the effectiveness in removal of VOCs, PM and bio-contaminants by six different air cleaners. According to their experiments, electrostatic precipitator and the combination of the mechanical particle filter and gas filter proved to be the most suitable solutions for particle removal and were highly energy effective. Moreover, they noticed that the plasma ionizer promotes particle deposition onto the surfaces of a room. A non-thermal plasma and photocatalytic oxidation were proposed as technologies for formaldehyde removal from indoor air by Zheng et al. (2022). All these technologies may be successively applied to improve the effectiveness of the air purifier proposed within this paper.

The results indicate that the air purifier demonstrated greater efficacy in removing inorganic or non-carbonate PM components in the opposite to organic chemicals. Organic species in PM are a group of uncountable chemicals with different chemical properties, different affinity to each other and different stability. Thus, the changes in chemical composition of PM and continue reactions on the surface of particulate matter are possible even in such a short time during filtering in the air purifier. As Zhang et al. (2011) noticed, it is always required to examine the by-products of filtration process. Sørensen et al. (2023) tested several kinds of indoor air cleaners, and they proved that some of them are unintentionally the source of volatile organic compounds through re-emission once they were caught by a filter or by the reactions of PM compounds. The air cleaner presented in our paper was equipped with a cyclone and electrostatic filter. The cyclones are able to remove particle with greater sizes of aerodynamic diameters (ca. 10 µm) depending on the design and construction. The electrostatic filter is able to filter the particles with smaller size of aerodynamic diameter of PM particles. If the system is sensitive to non-carbonate compounds, it means that elemental carbon which is the main adsorber and the entire organic matter remain unfiltered. This creates a need of incorporation of other microsystem for effective organic fraction removal, i.e. oxidating units where organic impurities are reduced to CO2 and H20.

Limitations

Undoubtedly, the development of ambient air cleaners poses some limitations which need to be overcome before practical implication. In the paper, we showed the results of preliminary tests of air purifier efficiency in removal of particulate matter and its specific components. As a next step, the air purifier should be investigated at different air flows and different outdoor conditions in order to define its optimal parameters of operation and to define the cut size of PM particles which the AP is sensitive to. Adaptability and durability of AP materials and optimisation of AP work to changing conditions are also important aspects of future work. Ambient air purifiers need to be designed and constructed to withstand harsh outdoor conditions, including temperature variations, moisture and exposure to UV radiation. The durability and adaptability of the air purifier’s materials and components should be assessed to ensure long-term effectiveness and reliability. Ipso facto, the air purifier must by tested in real conditions to assess its real effectiveness in cleaning the ambient air and the influence on cleaner air inside the buildings.

It is worth to notice that the effective work of ambient air purifiers may be disturbed by many factors which usually are difficult to predict, as environmental factors and pollutant types occurring in the atmosphere. Ambient air purification is influenced by various environmental factors such as wind speed, temperature, humidity and proximity to pollution sources. These factors can affect the dispersion and concentration of pollutants in ambient air. The air purifier’s performance should be evaluated under different environmental conditions to determine its effectiveness in various outdoor settings. Zhang et al. (2022) indicated that the use of cleaners with different filter units will elevate the level of PM filtration. They pointed out that with increase in wind speed, the effectiveness of filters decreases. Ambient air can contain a wide range of pollutants beyond particulate matter, including gases, volatile organic compounds and other precursors for ambient chemical transformations.

Conclusions

Based on the comprehensive analysis conducted and considering the innovative nature of the air purifier as a novel approach to outdoor purification utilizing renewable energy sources and achieving self-sufficiency in energy consumption, the following conclusions can be drawn:

  • Effective removal of particulate matter: The tested air purifier demonstrated a high level of effectiveness in removing particulate matter from the simulated ambient air. The filter exhibited a remarkable PM mass filtering efficiency of approximately 74%. It showcased notable success in reducing the presence of inorganic PM components, as indicated by the high removal efficiency of elements such as calcium (Ca), potassium (K), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr) and inorganic ions including sodium (Na+). This underscores the potential of the air purifier in improving ambient air quality by mitigating the concentration of harmful PM. It should be kept in mind that the ultimate effectiveness of the air purifier is entirely dependent on local actual conditions, such as wind speed, ambient air temperature, relative humidity and the intensity of local emissions, all of which affect the actual exposure to particulate matter.

  • Differentiated removal of inorganic and organic compounds: The analysis revealed that the air purifier showed higher effectiveness in removing inorganic or non-carbonate PM components compared to organic carbon compounds. However, further research and optimization efforts are needed to enhance the removal of organic carbon compounds and achieve a more balanced purification of both inorganic and organic pollutants. This should also be extended to include examinations of the air purifier’s ability to remove pollen and allergens.

  • Potential for air quality improvement: The utilization of renewable energy sources and the achievement of self-sufficiency in energy consumption make the air purifier a promising solution for ambient air purification. By eliminating the need for an electric grid and reducing CO2 emissions, the purifier offers a sustainable approach to improving air quality in various locations. The innovative technology has the potential to contribute significantly to global efforts aimed at mitigating air pollution and its detrimental effects on human health and the environment.

  • Future research and development: While the tested air purifier has demonstrated promising results, further research and development are crucial for optimizing its performance and expanding its capabilities. Addressing the challenges associated with the removal of organic pollutants, enhancing the sensitivity and accuracy of analytical methods and exploring advanced filtration technologies are important areas for future investigation. Additionally, comprehensive field studies and long-term monitoring are necessary to validate the effectiveness of the air purifier in real-world outdoor environments and assess its impact on air quality improvement.