Air Ions Research Articles

Effect of dry-wet cycles on mechanical properties of polyurethane porous mixture

ABSTRACT Polyurethane porous mixture (PUPM) is a novel material with potential to extend the service life of pervious pavement. The porous structure makes the interior of the pavement material inevitably exposed to frequent cyclic action of environmental factors. However, the mechanical property decay behaviour of PUPM under the dry-wet cycles formed by water, air and corrosive ions is still unclear. Therefore, the mechanical properties of PUPM under different dry-wet cycles were characterised by Marshall stability, splitting strength and uniaxial compression strength tests. The variations in the microscopic properties of PUPM were investigated by computed tomography (CT), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The grey entropy correlation theory was used to analyse the effect of variations in the functional groups of polyurethane on the mechanical properties of PUPM. It was concluded that the ageing of the polyurethane and the disruption of the bond at the binder-aggregate interface are the fundamental reasons for the mechanical property decay of PUPM. The influence of each functional group on the mechanical strength of the PUPM is in this descending order: amino groups linked to the carbonyl groups, carbonyl groups, ether bonds, methylene groups, and amino groups formed hydrogen bonds with water.

Study of Influence of Air Ions on the Growth Rate of Yeast Saccharomyces cerevisiae Based on Analytical Growth Model

The influence of the concentration of ions in a nutrient medium both on the surface charge and potential of a yeast cell and diffusion of nutrients through its membrane and on the productivity of baking yeast was studied theoretically. It was shown that the ionized molecules of air components (first of all, of oxygen and nitrogen) changes the concentration of ions in the medium, the surface charge and potential of the yeast cell. This feature affects the diffusion of nutrients through membrane into the cell. The growth rate of the yeast mass depends on the amount of electricity, transported by air ions in the nutrient medium, and is limited by its certain value. That is why the yeast mass growth equation take into account the amount of electricity transported by air ions into the nutrient medium. A priori calculation shows that the productivity of the baker’s yeast can increase by 12…17%.

Estimating aerosol particle removal in indoor air by ion-enhanced deposition

Small air ions have the ability to charge airborne particles, thereby increasing their accumulation on surfaces. Indoor air purification by applying ionization uses electrostatic particle deposition. Respiratory pathogens, including viruses and respiratory droplets carrying viruses or other pathogens, represent bioaerosols, whose particle size distributions contain increasingly larger proportion of fine and ultrafine particles, as the evaporation process proceeds. We have generated two model aerosols: the nebulized NaCl solution, resembling human saliva, and the cigarette smoke, having relatively low water content. We have conducted real life experiments of such surrogate aerosol particle deposition without ionization, using bipolar ionization, as well as using unipolar negative air ions. Particle number concentrations have been measured in the 10 nm–10 μm particle size range. The calculated deposition rates and aerosol particle half-life times were correlated with bioaerosol pathogens based on the core pathogen sizes. Bipolar ionizers emitting equal concentrations of positive and negative ions had low impact to the particle concentration decrease. Intense negative air ionization resulted in pronounced deposition rate increases, particularly in the particle size range of viruses including the SARS-CoV-2. The impact of negative air ionization was most pronounced in the same size range where the deposition rates without ionization were the lowest. Therefore, the results are very promising from the standpoint of air purification and bioaerosol pathogen removal, bearing in mind that the effect of ions will be most pronounced if the unipolar ion rich air stream is directed towards the breathing zone.

Revealing the sources and sinks of negative cluster ions in an urban environment through quantitative analysis

Abstract. Atmospheric cluster ions are important constituents in the atmosphere, and their concentrations and compositions govern their role in atmospheric chemistry. However, there is currently limited quantitative research on atmospheric ion compositions, sources, and sinks, especially in the urban atmosphere where pollution levels and human populations are intense. In this study, we measured the compositions of negative cluster ions and neutral molecules using an atmospheric pressure interface high-resolution time-of-flight mass spectrometer (APi-TOF) and a chemical ionization mass spectrometer in urban Beijing. Quantitative analysis of cluster ions was performed by their comparison with condensation sink (CS), reagent ions, and neutral molecules. We demonstrate the feasibility of quantifying cluster ions with different compositions using in situ-measured ion mobility distributions from a neutral cluster and air ion spectrometer (NAIS). The median concentration of negative cluster ions was 85 (61–112 for 25 %–75 %) cm−3 during the measurement period, which was negatively correlated with CS. The negative cluster ions mainly consisted of inorganic nitrogen-containing ions, inorganic sulfur-containing ions, and organic ions in the form of adducts with NO3- or HSO4-. The CHON-related organic ions accounted for over 70 % of the total organic ions. Although the molecules clustered with NO3- and HSO4- had similar compositions, we found that HSO4- clustered more efficiently with CHO and CHONnonNPs species (CHON excluding nitrated phenols), while NO3- clustered more efficiently with nitrated phenols (CHONNPs). Additionally, most organic ions were positively correlated with neutral molecules, resulting in similar diurnal cycles of organic ions and neutral molecules. However, an exception was found for CHONNPs, the concentration of which is also significantly influenced by the reagent ions NO3-. The charge fractions are generally higher for molecules with higher molecular weight and a higher oxidation state, and the opposite diurnal variations in charging fractions between H2SO4 and organic species indicate a charging competition between them. Finally, we choose HSO4- and C3H3O4- as representatives to calculate the contribution of different formation and loss pathways. We found their losses are condensational loss onto aerosol particles (73 %–75 %), ion–molecule reaction losses (19 %), and ion–ion recombination losses (6 %–8 %).

Single-Shot Multi-Frame Imaging of Femtosecond Laser-Induced Plasma Propagation.

Single-shot ultrafast multi-frame imaging technology plays a crucial role in the observation of laser-induced plasma. However, there are many challenges in the application of laser processing, such as technology fusion and imaging stability. To provide a stable and reliable observation method, we propose an ultrafast single-shot multi-frame imaging technology based on wavelength polarization multiplexing. Through the frequency doubling and birefringence effects of the BBO and the quartz crystal, the 800 nm femtosecond laser pulse was frequency doubled to 400 nm, and a sequence of probe sub-pulses with dual-wavelength and different polarization was generated. The coaxial propagation and framing imaging of multi-frequency pulses provided stable imaging quality and clarity, as well as high temporal/spatial resolution (200 fs and 228 lp/mm). In the experiments involving femtosecond laser-induced plasma propagation, the probe sub-pulses measured their time intervals by capturing the same results. Specifically, the measured time intervals were 200 fs between the same color pulses and 1 ps between the adjacent different. Finally, based on the obtained system time resolution, we observed and revealed the evolution mechanism of femtosecond laser-induced air plasma filaments, the multifilament propagation of femtosecond laser in fused silica, and the influence mechanism of air ionization on laser-induced shock waves.

A self-powered triboelectric negative ion generator in pipeline

Indoor air quality plays a critical role in maintaining human health and well-being. In this study, a novel self-powered and high-efficiency negative air ion (NAI) generator in pipeline is proposed for air purification in the ventilation system. The self-power is achieved by utilizing a novel device of wind energy triboelectric nanogenerator (WE-TENG) to efficiently harvest wind energy in the pipeline. The present WE-TENG of investigation can reach a high rotation speed of 1300 rpm at 5.5 m/s in the pipe with a pressure drop of 175 Pa. After the power management circuit, the self-powered NAI generator is capable to drive 21 carbon-fiber electrodes to generate NAIs, with a generation rate of 23.14 μC/s. The self-powered NAI generator efficiently generates a high volume of NAIs in the pipeline, harnessing the air-purifying properties of NAIs, thereby making a significant impact on the practical application of self-powered indoor air purification systems based on TENG.

Measurement report: Molecular-level investigation of atmospheric cluster ions at the tropical high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes

Abstract. Air ions are the key components for a series of atmospheric physicochemical interactions, such as ion-catalyzed reactions, ion-molecule reactions, and ion-induced new particle formation (NPF). They also control atmospheric electrical properties with effects on global climate. We performed molecular-level measurements of cluster ions at the high-altitude research station Chacaltaya (CHC; 5240 m a.s.l.), located in the Bolivian Andes, from January to May 2018 using an atmospheric-pressure-interface time-of-flight mass spectrometer. The negative ions mainly consisted of (H2SO4)0–3⚫HSO4-, (HNO3)0–2⚫NO3-, SO5-, (NH3)1–6⚫(H2SO4)3–7⚫HSO4-, malonic-acid-derived, and CHO / CHON⚫(HSO4- / NO3-) cluster ions. Their temporal variability exhibited distinct diurnal and seasonal patterns due to the changes in the corresponding neutral species' molecular properties (such as electron affinity and proton affinity) and concentrations resulting from the air masses arriving at CHC from different source regions. The positive ions were mainly composed of protonated amines and organic cluster ions but exhibited no clear diurnal variation. H2SO4–NH3 cluster ions likely contributed to the NPF process, particularly during the wet-to-dry transition period and the dry season, when CHC was more impacted by air masses originating from source regions with elevated SO2 emissions. Our study provides new insights into the chemical composition of atmospheric cluster ions and their role in new particle formation in the high-altitude mountain environment of the Bolivian Andes.

Achieving Ultra‐High Voltage (≈10 kV) Triboelectric Nanogenerators

AbstractWith the intrinsic characters of high voltage and low current, triboelectric nanogenerators (TENGs) serving as green high voltage (HV) power source exhibit excellent practicability and safety compared to traditional HV power sources. To further simplify the TENG‐based HV power source system, a single electrode mode TENG (SE‐TENG) with simple wiring is first employed to generate ultra‐high voltage power in this work. By optimizing surface charge density and the thickness of packing layer between the primary electrode and reference electrode, a record value of 12.7 kV is achieved for SE‐TENGs. Furthermore, a calculation method based on a capacitance model is proposed to accurately measure the open voltage of TENG with a wide range (over 10 kV). The SE‐TENG‐based HV power source is successfully applied to power electronics and generates negative air ions for air cleaning. This work significantly simplifies TENG‐based HV power sources, and is expected to enrich the diversity of high‐voltage applications based on the reach of existing technologies.

On the Radon-Related Mechanism of the Seismo- and Volcanogenic Geomagnetic Anomalies: Experiments in Tlamacas Mountain (Volcano Popocatepetl Area) and Electrode Effect Model

The noise-like behavior of the geomagnetic anomalies observed in Tlamacas station (volcano Popocatepetl, Mexico), linked to the ionization produced by intensive radon release, are presented in the experimental part of this study. The magnetic field perturbations produced by charge spreading currents within the fair-weather electric field are considered in the theoretical model based on the electrode. The electric charges are generated by the air ionization due to radon emanation. The simulations demonstrated that the ionization of the air leads to magnetic field perturbations of about 0.001–0.1 nT in the ULF (ultra low frequency) range 10−3–10−1 Hz. Magnetic field perturbations can be higher when the radon emanation occurs in a region with terrain irregularities.

GHz bursts in MHz burst (BiBurst) enabling high-speed femtosecond laser ablation of silicon due to prevention of air ionization

For the practical use of femtosecond laser ablation, inputs of higher laser intensity are preferred to attain high-throughput material removal. However, the use of higher laser intensities for increasing ablation rates can have detrimental effects on ablation quality due to excess heat generation and air ionization. This paper employs ablation using BiBurst femtosecond laser pulses, which consist of multiple bursts (2 and 5 bursts) at a repetition rate of 64 MHz, each containing multiple intra-pulses (2–20 pulses) at an ultrafast repetition rate of 4.88 GHz, to overcome these conflicting conditions. Ablation of silicon substrates using the BiBurst mode with 5 burst pulses and 20 intra-pulses successfully prevents air breakdown at packet energies higher than the pulse energy inducing the air ionization by the conventional femtosecond laser pulse irradiation (single-pulse mode). As a result, ablation speed can be enhanced by a factor of 23 without deteriorating the ablation quality compared to that by the single-pulse mode ablation under the conditions where the air ionization is avoided.

Numerical simulation of hypersonic plasma flow field disturbed by pulsed discharge

A plasma sheath will be generated around the hypersonic vehicle during reentry, and a large number of electrons in the plasma sheath will seriously affect the communication between the vehicle and the ground station. In order to reduce the electron number density of the hypersonic vehicle plasma sheath, a method of using pulsed discharge active actuation to regulate the plasma sheath is proposed. Based on the air dissociation and ionization model including 11 components and 32 chemical reactions, the reduction effect of pulsed discharge actuation on the electron density of plasma sheath is studied by numerical simulation. A first test is performed in which the pulsed discharge is compared with the plasma jets' experimental data. Then, a second test compared the plasma flow field around the RAMC-II vehicle with the flight test and NASA data. In these two tests, the simulation results are basically consistent with the experimental results. Finally, the effect of pulsed discharge with different energy density on the plasma sheath electron density is studied. The numerical results show that the interaction between the high-pressure aerodynamic actuation generated by the actuator and the plasma sheath produces an obvious shock wave, which blocks electrons from flowing downstream, reduces the velocity and pressure of the flow field behind the shock wave, and, finally, makes the electron density downstream of the actuator attenuate significantly, with the maximum attenuation amplitude of about 35%. Compared with the traditional method, the method proposed in this paper requires less space, load, and source power and has certain engineering feasibility.

The effect of storage conditions on some tomato varieties, during the postharvest period

In this study, an analysis was made of how the variety and storage conditions influence the keeping of tomatoes in the fresh conditions, in the post-harvest period. The fruits of three varieties of tomatoes were stored in different technological conditions: at ambient temperature (20-22 °C), with and without air ionization; at a temperature of 10-12 °C, with and without modified atmosphere; and at a temperature of 3-5 °C. The firmness of the pulp and some biochemical components were analysed, respectively the soluble dry matter, the total sugar, the acidity and vitamin C. For the studied varieties the mass losses were appreciated and losses due to rotten during the analysed period. The observations made during the storage of tomatoes in different conditions confirmed that, in general, tomatoes are relatively easily alterable products, the storage period being between 5 days and 15 days. The experimental research carried out showed the fact that the fresh storage time of tomatoes varies significantly depending on the storage conditions but also depending on the tomato variety investigated. The main problem was represented by the large volume of losses due to rotting recorded in one of the varieties regardless of the storage conditions and also the very large differences in losses due to rotting existing between the varieties within the same storage conditions.

Safety of digital learning environment for the health of high school and university students in distance learning

The development of technologies using the electromagnetic field (EMF) of the radio frequency range has become a leading trend related to the need for wireless data transmission. This made it possible for distance learning of schoolchildren and students in a dangerous epidemic situation. Accumulated data on the sensitivity of the human body to the action of EMF. The purpose of the work is to assess the conditions of teaching schoolchildren in computer science classrooms, as well as the impact of online learning on the health of high school students and university students. Based on the results of an online survey of schoolchildren and students according to the author’s questionnaire, a database was formed and an assessment of the conditions of distance learning was carried out. With the use of instrumental research, an assessment of the learning conditions in computer science classrooms was carried out. The materials were processed using the reliability criterion χ2 and the health risk assessment RR. Control data in computer science classrooms showed non-compliance of temperature, air humidity, air ionization, illumination, noise with regulatory requirements, except for EMF levels. With online learning, a high duration of stay of high school students and students in a digital environment has been established, including the learning process, homework, and leisure time on the Internet. In the structure of complaints related to studying online and doing homework, there were: visual impairment over the past year, headaches, back pain, irritability, eye fatigue, a feeling of dryness in the eyes. The time for sleep and physical activity decreased. Data have been obtained confirming the need to protect the health of students in a digital environment with the provision of safe conditions for visual work, limiting the time of use of digital devices, increasing the literacy of all users.

Seismo Ionospheric Anomalies around and over the Epicenters of Pakistan Earthquakes

Global Navigation Satellite System (GNSS)-based ionospheric anomalies are nowadays used to identify a possible earthquake (EQ) precursor and hence a new research topic in seismic studies. The current study also aims to provide an investigation of ionospheric anomalies associated to EQs. In order to study possible pre-and post-seismic perturbations during the preparation phase of large-magnitude EQs, statistical and machine learning algorithms are applied to Total Electron Content (TEC) from the Global Positioning System (GPS) and Global Ionosphere Maps (GIMs). We observed TEC perturbation from the Sukkur (27.8° N, 68.9° E) GNSS station near the epicenter of Mw 5.4 Mirpur EQ within 5–10 days before the main shock day by implementing machine learning and statistical analysis. However, no TEC anomaly occurred in GIM-TEC over the Mirpur EQ epicenter. Furthermore, machine learning and statistical techniques are also implemented on GIM TEC data before and after the Mw 7.7 Awaran, where TEC anomalies can be clearly seen within 5–10 days before the seismic day and the subsequent rise in TEC during the 2 days after the main shock. These variations are also evident in GIM maps over the Awaran EQ epicenter. The findings point towards a large emission of EQ energy before and after the main shock during quiet storm days, which aid in the development of lithosphere ionosphere coupling. However, the entire analysis can be expanded to more satellite and ground-based measurements in Pakistan and other countries to reveal the pattern of air ionization from the epicenter through the atmosphere to the ionosphere.

Antioxidant effect of negative air ions in correction of hepatic dysfunction in mechanical jaundice

Aim. To evaluate the effectiveness of negative air ions in eliminating hepatic dysfunction in mechanical jaundice. Materials and methods. Experiments on 30 rats were carried out in two series. In the first experiment series, the mechanical jaundice was simulated with subsequent decompression of common bile duct and injection of 0.9% sodium chloride solution in the volume of 40 ml/kg. In the second experimental series, negative air ions (3 mln particles per 1 cm3 ) were exposed for 60 min once a day over the course of 12 days. The levels of bilirubin, malondialdehyde, ALT and AST, alkaline phosphatase and catalase were studied. Results. The use of negative air ions in mechanical jaundice contributed to significant correction of the liver functional activity. Concentration of total and direct bilirubin decreased to 84.4 ± 7.6 and 42.1 ± 5.4 μmol/l, which is 25% and 56% lower than in the control series. The activity of AST, ALT, and alkaline phosphatase, as well as the concentration of malondialdehyde were reported to be lower in than control series (by 17%, 22%, 18%, 47%, correspondingly), while the catalase activity was 3.6 times higher. Conclusion. Application of negative air ions in treatment of mechanical jaundice stimulates production of own antioxidative enzymes which protect hepatocytes from free radical damage.

Intelligent operation, maintenance, and control system for public building: Towards infection risk mitigation and energy efficiency

During the post-COVID-19 era, it is important but challenging to synchronously mitigate the infection risk and optimize the energy savings in public buildings. While, ineffective control of ventilation and purification systems can result in increased energy consumption and cross-contamination. This paper is to develop intelligent operation, maintenance, and control systems by coupling intelligent ventilation and air purification systems (negative ion generators). Optimal deployment of sensors is determined by Fuzzy C-mean (FCM), based on which CO2 concentration fields are rapidly predicted by combing the artificial neural network (ANN) and self-adaptive low-dimensional linear model (LLM). Negative oxygen ion and particle concentrations are simulated with different numbers of negative ion generators. Optimal ventilation rates and number of negative ion generators are decided. A visualization platform is established to display the effects of ventilation control, epidemic prevention, and pollutant removal. The rapid prediction error of LLM-based ANN for CO2 concentration was below 10% compared with the simulation. Fast decision reduced CO2 concentration below 1000 ppm, infection risk below 1.5%, and energy consumption by 27.4%. The largest removal efficiency was 81% when number of negative ion generators was 10. This work can promote intelligent operation, maintenance, and control systems considering infection prevention and energy sustainability.

Effects of Increasing Indoor Negative Air Ions on Cognitive Performance and Health of High Pure CO2 Level-Exposed College Students

Cognitive performance is essential to foster learning. High CO2 concentrations are common in classrooms and can lead to reduced cognitive performance. Negative air ions (NAIs) can improve cognitive performance. This study explored the effects of indoor NAIs on the cognitive performance and health of college students exposed to a high pure CO2 environment. Forty college students were exposed to four sets of conditions (NAIs+500 ppm CO2, 500 ppm CO2, NAIs+2500 ppm CO2, and 2500 ppm CO2). Participants’ cognitive performance, including reasoning, short-term memory, concentration, and verbal ability, was assessed under each condition using the Cambridge Brain Sciences tool. Acute health symptoms were investigated using a subjective questionnaire, and simultaneously, participants’ blood pressure, heart rate, and lung function were tested. Analysis of variance (ANOVA) in a repeated-measures design was used to analyze the effects of different conditions on cognitive performance and health symptoms. The results revealed that the different levels of CO2 and NAIs had a significant effect on cognitive performance after one hour of exposure and had no significant effect after three hours of exposure. Compared with 500 ppm CO2, 500 ppm CO2+NAIs resulted in better reasoning skills, short-term memory, and verbal skills, and 2500 ppm CO2 led to poorer reasoning skills. The addition of NAIs to 2500 ppm CO2 improved reasoning skills, short-term memory, and verbal skills. The benefits of adding NAIs to high pure CO2 condition on cognitive performance are more noticeable than those to low CO2 condition. Moreover, adding NAIs can reduce nasal irritation or dryness, skin irritation or dryness, sleepiness symptoms, and heart rate elevation caused by pure CO2. However, the benefits of NAIs on health symptoms and physiology were not observed under the 500 ppm CO2 condition. Adding NAIs to a high pure CO2 level is an effective means to improve the cognitive performance and health of college students.

Thermodynamic instability of the atmospheric boundary layer stimulated by tectonic and seismic activity

The number of researches during the recent two decades clearly demonstrated that a few weeks/days before moderate and strong earthquakes the specific thermal anomalies emerge within the earthquake preparation zones. In these papers some physical mechanisms were proposed, but they could not explain the avalanche character of the observed anomalies. In our works we studied a rich collection of pre-earthquake thermal/meteorological cases and proposed an explanation of the physical mechanism. We consider the Boundary Layer (BL) within the earthquake preparation zone as an open non-equilibrium system with energy dissipation. We show, that the external impact of ionization and following plasma chemical reactions between new-formed ions provide a specific autocatalytic exothermic reaction with a sharp increase of the thermal energy release. We use atmosphere chemical potential (ACP) as a parameter to estimate energy for processes connected with condensation. Monitoring of the latent heat release and ACP in the boundary layer can be used for the detection of tectonic and seismic activity and artificial phenomena, connected with air ionization. The statistical studies of strong M ≥ 6.5 global earthquakes demonstrated the high statistical confidence of ACP as the short-term earthquake precursor.

The Lagging Effect of Precipitation on NAIs Concentrations on Rainy Days in Wuyi Mountain National Park, China

Precipitation (PRE) is an essential factor that affects the negative air ions (NAIs) concentrations. However, the mechanism of NAIs concentrations and their influencing factors on rainy and non-rainy days remains unclear. Here, we used hourly data of NAIs concentrations and meteorological data in 2019 to analyze the distribution of NAIs concentrations and its influencing factors on rainy and non-rainy days in the Wuyi Mountain National Park (WMNP) of China, which was listed as a World Cultural and Natural Heritage Site in 1999. The results indicated that the NAIs concentrations on rainy days were significantly higher than on non-rainy days. However, the NAIs concentrations on rainy days were slightly higher than on the first and second days after rainy days. Then, the NAIs concentrations were significantly reduced on the third day and after that. Thus, rainy days lead to a 2-day lag in the smooth reduction of NAIs on non-rainy days after rainy days. NAIs concentrations were significantly correlated with the relative humidity (RHU) on both rainy and non-rainy days. By analyzing the meteorological factors on NAIs for ranking the feature importance scores on rainy and non-rainy days, PRE was ranked first on rainy days, and sea level pressure (PRS_Sea) and temperature (TEM) were ranked first and second on non-rainy days, respectively. Based on the univariate linear regression model (ULRM), NAIs concentrations responded strongly (higher absolute slope values) to RHU on rainy days and to pressure (PRS), visibility (VIS), water vapor pressure (VAP), TEM, and ground surface temperature (GST) on non-rainy days. The results highlight the importance of PRE in the lag time of NAIs concentrations on rainy and non-rainy days.

Negative Air Ion (NAI) Dynamics over Zhejiang Province, China, Based on Multivariate Remote Sensing Products

Negative air ions (NAIs), which are known as the “air vitamin”, have been widely used as a measure of air cleanness. Field observation provides an alternative way to record site-level NAIs. However, these observations fail to capture the regional distribution of NAIs due to the limited number of sites. In this study, satellite-based bio-geophysical parameters from the climate, topography, air quality, vegetation, and anthropogenic intensity were used to estimate the daily NAIs with the Random Forest model (RF). In situ NAI observations over Zhejiang Province, China were incorporated into the model. Daily NAIs were averaged to capture the spatio-temporal distribution. The results showed that (1) the RF algorithm performed better than traditional regression analysis and the common BP neural network to generate regional NAIs at a spatial scale of 500 m over the larger scale, with an RMSE of 258.62, R2 of 0.878 for model training, and R2 of 0.732 for model testing; (2) in the variable importance measures (VIM) analysis, 87.96% of the NAI variance was caused by the elevation, aspect, slope, surface temperature, solar-induced chlorophyll fluorescence (SIF), relative humidity (RH), and the concentration of carbon monoxide (CO), while path analysis indicated that SIF was one of the most important factors affecting NAI concentration across the whole region; (3) NAI concentrations in 87.16% of the region were classified above grade III (>500 ions cm−3), which was able to meet the needs of human health maintenance; (4) the highest NAI concentration was distributed over the southwest of the Zhejiang Province, where forest land dominates. The lowest NAI concentration was mostly found in the northeast regions, where urban areas are well-developed; and (5) among different land types, the NAI concentrations were ranked as forest land > water bodies > barren > grassland > croplands > urban and built-up. Among different seasons, summer and winter have the highest and lowest NAIs, respectively. Our study provided a substantial reference for ecosystem services assessment in Zhejiang Province.