Filtered Air Research Articles

Early detection of infestation by mustard aphid, vegetable thrips and two-spotted spider mite in bok choy with deep neural network (DNN) classification model using hyperspectral imaging data

Although exclusion measures (e.g., air filters, biosecurity practices) can be employed to prevent occurrence of pest outbreaks, indoors vegetable farms in Singapore are still susceptible to various arthropod pests. Due to strong interest from the industry to pursue pesticide-free production, indoors pest management is often focused on early detection for timely containment and eradication, implying the importance of robust and vigorous pest monitoring programs. In recent years, application of machine vision technologies, especially hyperspectral imaging (HSI), has been studied for their capacity to early detect pest infestation. However, there is a lack of studies conducted in actual indoor environments and on multiple arthropod pests. Thus, this study aimed to non-destructively collect hyperspectral data of bok choy Brassica rapa subspecies chinensis which were healthy or infested with either mustard aphids Lipaphis erisymi, vegetable thrips Echinothrips americanus or two-spotted spider mites Tetranichus urticae in indoor environment to build deep neural network (DNN) classification model for early detection. Based on HSI data of control and infested plants collected daily over a period of two weeks, we found that point percentage change (PPC) values associated with leaf reflectance in 420–440 nm, 500–520 nm, 620–637 nm, 720–800 nm, and 850 nm were sensitive to infestation by the mentioned arthropod pests. Deep Neural Network (DNN) classification models trained on collected HSI data were found to outperform Linear Discriminant Analysis (LDA) and Support Vector Machine (SVM) classification models. DNN models achieved 92.8 ± 0.4 % overall classification accuracy across all days. As early as two days after infestation, DNN models could achieved classification precision values of 96.4 %, 96.9 %, 93.9 % and 100 % for control plants and plants infested with either aphids, spider mites or thrips respectively. These results highlight the feasibility of multiclass early detection of different arthropod pests and the potential of HSI system coupled with DNN classification as an autonomous plant health monitoring tool in indoor crop production.

A comprehensive review of urban vegetation as a Nature-based Solution for sustainable management of particulate matter in ambient air.

Air pollution is one of the most pressing environmental threats worldwide, resulting in several health issues such as cardiovascular and respiratory disorders, as well as premature mortality. The harmful effects of air pollution are particularly concerning in urban areas, where mismanaged anthropogenic activities, such as growth in the global population, increase in the number of vehicles, and industrial activities, have led to an increase in the concentration of pollutants in the ambient air. Among air pollutants, particulate matter is responsible for most adverse impacts. Several techniques have been implemented to reduce particulate matter concentrations in the ambient air. However, despite all the threats and awareness, efforts to improve air quality remain inadequate. In recent years, urban vegetation has emerged as an efficient Nature-based Solution for managing environmental air pollution due to its ability to filter air, thereby reducing the atmospheric concentrations of particulate matter. This review characterizes the various mitigation mechanisms for particulate matter by urban vegetation (deposition, dispersion, and modification) and identifies key areas for further improvements within each mechanism. Through a systematic assessment of existing literature, this review also highlights the existing gaps in the present literature that need to be addressed to maximize the utility of urban vegetation in reducing particulate matter levels. In conclusion, the review emphasizes the urgent need for proper air pollution management through urban vegetation by integrating different fields, multiple stakeholders, and policymakers to support better implementation.

Preparation of modified halloysite nanotubes@Ag3PO4/polyacrylonitrile electrospinning membranes for highly efficient air filtration and disinfection

Particulate matters (PMs) and airborne bacteria are among the most severe indoor air issues due to their substantial implications for human health. Therefore, it was imperative to conduct a comprehensive investigation on air filtration materials with superior filtration performance and antibacterial properties. Here, the m-Hal@Ag3PO4 composite particles were prepared by using modified halloysite nanotubes (m-Hal) as the support of Ag3PO4 nano-photocatalysts. These composite antibacterial particles were uniformly dispersed within a polyacrylonitrile (PAN) solution and were subsequently electrospun into m-Hal@Ag3PO4/PAN composite nanofiber membranes (CNMs) possessing excellent antibacterial properties. The incorporation of 30 wt% m-Hal@Ag3PO4 additionally enhanced the filtration efficiency of PM0.3 to 99.9%, at an airflow rate of 32 L/min, while concurrently reducing the pressure drop by 36.7%. The photocatalytic degradation efficiency of CNMs towards ciprofloxacin reached 99%. The antibacterial experiments demonstrated that CNMs exhibited potent antibacterial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli)under dark and light conditions. Under visible light irradiation, the average diameter of the inhibition zone for the composite membrane surpassed that observed under dark conditions, indicating a predominant enhancement in its antibacterial efficacy through photocatalysis. The enhanced photocatalytic performance and excellent stability can be attributed to the incorporation of Ag3PO4 with m-Hal, which enhanced the dispersibility and facilitated efficient carrier separation of Ag3PO4. The present type of CNMs exhibited the advantages of high efficiency and low resistance air filtration, photodegradation ability, and recyclability, thereby enhancing the efficacy and lifespan of PMs filtration, bacteria disinfection, and antibiotic degradation. This offered a novel concept and viable approach for indoor air and water purification based on electrospinning technology.

Energy-efficient operation of portable air cleaners based on real-time prediction of non-uniform concentrations of indoor air pollutants in open offices

In an open office environment with high occupant density and random occupancy patterns, excessive energy consumption is often observed because mechanical ventilation (MV) is usually designed and operated assuming a full-occupancy-based ventilation rate (VR). Considering the duo challenges of post-pandemic and climate change, this study proposes a real-time monitoring and optimization approach for operating portable air cleaners (PACs) to assist and reduce the energy consumption of the MV while maintaining the minimal VR and improving indoor air quality (IAQ). The approach was as follows. First, by assuming four VRs and 36 different emission sources, numerical simulations were conducted and validated based on an actual open office on non-uniform concentrations of a surrogate for indoor air pollutants (IAPs) throughout the breathing zone. Second, the pre- and post-purified IAP distributions were obtained using a limited number of sensors and trained by two artificial neural networks. Third, the real-time optimization of PACs’ on/off operation and placements was accomplished by the particle swarm optimization algorithm to balance energy output and improve IAQ simultaneously. Results showed that by deploying four sensors, the predictions of post-purifying concentrations were in acceptable accuracy (i.e., CV-RMSE <2.0%) within 30–40s. Using at most three PACs resulted in a significant decline in local IAP concentration levels. Meanwhile, an average reduction of total energy consumption of MV and PACs was 34.6% compared to using MV to reach the same levels. Overall, this study supports the use of PACs to assist MV in achieving energy efficiency and good IAQ.

THE DEVELOPMENT OF AUTOMATIC CIGARETTE SMOKE DETECTION SYSTEM USING TA12-100 AND MQ-135 SENSORS

Indonesia is ranked 3rd with the highest number of active smokers in the world after India and China. Cigarettes contain more than 4000 chemical compounds that are harmful to active smokers and passive smokers. The large number of active smokers in Indonesia also has an impact on passive smokers where passive smokers also inhale cigarette smoke. The purpose of this research is to build an automatic cigarette smoke detector to support air hygiene control, protect passive smokers, and save electricity used. The stages in designing this research include analysis of product specifications, assembly, programming, and trials. This study was designed using Arduino UNO as the microcontroller, the MQ-135 sensor as a tool to detect cigarette smoke, the TA12-100 sensor to calculate electrical power consumption, the relay as an automatic switch, and the exhaust fan as a smoke neutralizer. The results of this study are that the MQ-135 sensor can detect cigarette smoke properly with the Relay as an automatic switch that functions to turn on the exhaust fan automatically. Based on the test results on the TA12-100 sensor, the consumption of electrical energy with an automatic mechanism is more efficient than the consumption of electrical energy in a manual way, with a difference of 0.0000385 kWH and Rp. 0.05205. Future research could focus on developing a more complex system for overall air cleanliness control, rather than just focusing on cigarette smoke detection.

Evaluating portable air cleaner effectiveness in residential settings to reduce exposures to biomass smoke resulting from prescribed burns.

Prescribed burning is the most common method employed to reduce fuel loads in flammable landscapes. This practice is designed to reduce the hazard associated with uncontrolled bushfires. Prescribed burns are frequently conducted close to residential areas, and the associated smoke impacts can adversely affect community health. Particulate matter is the predominant pollutant within the smoke and is strongly and consistently linked with adverse health effects. Outdoor smoke readily infiltrates buildings and reduces the quality of indoor air. Portable air cleaners containing high-efficiency particulate air (HEPA) filters are a promising indoor air quality intervention for reducing outdoor smoke exposure. We provided 10 homes from semirural regions of Victoria, Australia, with HEPA cleaners and conducted continuous monitoring of indoor and outdoor fine particulate matter (PM2.5) for 2-4 weeks during prescribed burning periods. We calculated the potential improvements to indoor air quality when operating a HEPA cleaner during a smoke episode. Ventilation measures were conducted to identify points of smoke ingress and housing characteristics that could lead to higher infiltration rates. Depending on the house, the use of HEPA cleaners resulted in a reduction in indoor PM2.5 concentrations of 30-74%. HEPA cleaners have the potential to substantially improve indoor air quality during episodic smoke episodes.

347 Aerodynamic Size Distribution of SARS-CoV-2 Aerosol Shedding

OBJECTIVES/GOALS: We designed the Biocascade Exhaled Breath Sampler (BEBS) to characterize viral aerosol shedding among individuals with influenza and other respiratory virus infections. We first aimed to test the BEBS on volunteer COVID-19 cases and report the aerodynamic size distribution of exhaled breath aerosol particles carrying SARS-CoV-2 RNA. METHODS/STUDY POPULATION: From June 15 through December 15, 2022, we recruited 27 PCR-confirmed COVID-19 cases from a college campus and the surrounding community to provide 30-minute breath samples into a well-validated Gesundheit-II (G-II) exhaled breath aerosol sampler. Among these individuals, 17 provided an additional exhaled breath sample into the newly designed BEBS. We quantified samples for viral RNA using reverse transcription digital polymerase chain reaction (RT-dPCR) and determined the viral RNA copies collected within two aerosol size fractions (≤5 µm and &gt;5 µm in diameter) from the G-II, and four aerosol size fractions (&lt;1.15 µm, 1.15–3.2 µm, 3.3–8.2 µm, and &gt;8.2 µm) from the BEBS. RESULTS/ANTICIPATED RESULTS: Individuals with a SARS-CoV-2 Omicron BA.4 or BA.5 infection shed virus in aerosols at an average rate of 7.5x103 RNA copies per 30-minute G-II sample, with 78% of the total RNA in aerosols ≤5 µm in diameter. Among the BEBS samples, 10% of the total viral RNA was detected in aerosols &lt;1.15 µm, 43% in 1.15–3.2 µm, 37% in 3.3–8.2 µm, and 10% in the &gt;8.2 µm size fraction. Based on viral RNA loads, our results indicate that exhaled aerosols ≤3.2 µm contribute the majority of SARS-CoV-2 inhalation exposure. DISCUSSION/SIGNIFICANCE: Our data provide additional evidence that respirable aerosols contribute to the spread of SARS-CoV-2. Thus, our data suggest that mitigation measures designed to reduce infectious aerosol inhalation, such as ventilation and the use of air cleaners and respirators, are needed to control the spread.

Pentagon Found Daily, Metagenomic Detection of Novel Bioaerosol Threats to Be Cost-Prohibitive: Can Virtualization and AI Make It Cost-Effective?

In 2022, the Pentagon Force Protection Agency found threat agnostic detection of novel bioaerosol threats to be "not feasible for daily operations" due to the cost of reagents used for metagenomics, cost of sequencing instruments, and cost of labor for subject matter experts to analyze bioinformatics. Similar operational difficulties might extend to many of the 280,000 buildings (totaling 2.3 billion square feet) at 5,000 secure US Department of Defense military sites, 250 Navy ships, as well as many civilian buildings. These economic barriers can still be addressed in a threat agnostic manner by dynamically pooling samples from dry filter units, called spike-triggered virtualization, whereby pooling and sequencing depth are automatically modulated based on novel biothreats in the sequencing output. By running at a high average pooling factor, the daily and annual cost per dry filter unit can be reduced by 10 to 100 times depending on the chosen trigger thresholds. Artificial intelligence can further enhance the sensitivity of spike-triggered virtualization. The risk of infection during the 12- to 24-hour window between a bioaerosol incident and its detection remains, but in some cases it can be reduced by 80% or more with high-speed indoor air cleaning exceeding 12 air changes per hour, which is similar to the rate of air cleaning in passenger airplanes in flight. That level of air changes per hour or higher is likely to be cost-prohibitive using central heating ventilation and air conditioning systems, but it can be achieved economically by using portable air filtration in rooms with typical ceiling heights (less than 10 feet) for a cost of approximately $0.50 to $1 per square foot for do-it-yourself units and $2 to $5 per square foot for high-efficiency particulate air filters.

Improvements in swine herd biosecurity reduce the incidence risk of porcine reproductive and respiratory syndrome virus in breeding herds in the Midwestern United States.

Porcine reproductive and respiratory syndrome (PRRS) is a significant disease of swine. The purpose of this study was to determine whether application of a comprehensive, science-based approach to breeding herd biosecurity, known as next-generation biosecurity (NGB), could reduce PRRS incidence risk across a large commercial production company. Pigs (381,404 sows across 76 breeding herds). From 2009 to 2020, the annual incidence risk of PRRS in sow farms managed by the same company averaged 33%, ranging from 20% to 50%. To measure the effect of NGB on PRRS incidence risk, a retrospective cohort study was conducted from July 1, 2021, to June 30, 2023, across breeding herds managed by the same company. During the analysis, 2 groups of herds emerged: those that implemented protocols for all phases of NGB (NGB COMPLETE), and those that implemented all described protocols of biosecurity except for air filtration (NGB INCOMPLETE). During the 2-year assessment period, 56 breeding herds were classified as NGB COMPLETE, while 20 herds were NGB INCOMPLETE. The PRRS incidence risk in NGB COMPLETE herds was 8.9% as compared to 40.0% in NGB INCOMPLETE herds. From disease year 1 (July 1, 2021, to June 30, 2022) and disease year 2 (July 1, 2022, to June 30, 2023), system-wide PRRS incidence risk was 8.6% and 9.2%, respectively. The association between NGB status and PRRS incidence risk for the 2-year period was statistically significant at a P value of .006. Results of the present report provided evidence that improvements in biosecurity result in lower PRRS incidence risk under large-scale commercial swine production conditions.

Return Air Grille Position in a Cleanroom for Medicinal Packaging Using CFD Method

A cleanroom is a highly controlled environment; therefore, air quality is of significant concern, and specific physical and microbiological requirements must meet the standard. In addition to the number of particles, another critical parameter in a cleanroom is temperature. USP (The United States Pharmacopeia) 797 recommends that the temperature of a cleanroom be around 20 °C. Air quality is achieved through several parameters and components, such as using a high-efficiency particulate air filter (HEPA), the amount of fresh air entering the room, temperature, pressure difference, and airflow direction. In this study, the cooling load of the room for the filling and sealing process was calculated, and the airflow and temperature distribution patterns between two parameters of the return air grille (RAG) position were compared using Computational Fluid Dynamics (CFD). The first parameter, RAG 1, was placed above the ceiling, while the second parameter, RAG 2, was set on the sidewall. Based on the results of the study, it was found that the heat load generated from the room was 6.99 kW with a cooling coil capacity amounting to 10.77 kW. Moreover, the supply airflow rate was 371.66 l/s. Based on the results of the simulation modelling, it was found that the RAG positioned on the sidewall was more ideal than the RAG positioned above the ceiling since the temperature was more evenly distributed in the room where the RAG was positioned on the sidewall.

Airborne 210Pb, Si, Zn and Pb as tracers for atmospheric pollution in Helsinki metropolitan area.

This study analyzed 16070 daily and 608 weekly air filter samples from the Helsinki metropolitan area collected between 1962 and 2005. The aim was to use the Potential Source Contribution Function (PSCF) to determine potential sources of silicon (Si), zinc (Zn), lead (Pb), and radioactive isotope 210Pb. The main sources for Si and Pb were industrial activities, particularly mining, metal industry, and traffic. Common source areas for Zn and 210Pb were identified in the eastern and southeastern parts of the measuring site.

Study on Exhaust Gas Characteristics of SI Engine Using Fuel (Gasoline) & HHO Gas

Experiments have been carried out to investigate the effect of HHO gas on the emission and performance of SI engines. Water was converted into hydrogen and oxygen consisting of a 2:1 volume ratio by electrolysis process, which is called HHO (oxyhydrogen gas). An HHO fuel cell had been fabricated to generate the HHO gas required to feed the engine. This HHO is then mixed with filtered air, which is after the air filter system and before the inlet manifold system of the vehicle. In this investigation, a 125-cc single-cylinder 4-stroke air-cooled engine was used. The exhaust gas characteristics were sampled and measured using a gas analyzer. It was observed that when HHO gas had been introduced into the air/fuel mixture, it consequently reduced the concentration of NO, NOx, CO, engine temperature, and HC by about 50%, 50%, 38%, 5% & and 45% respectively. Also, a reduction in fuel consumption is noticed for the same engine RPM and load conditions when HHO gas was imported into the A/F mixture. Also, when HHO is introduced into the system, the concentration of O2 CO2 increases by about 50% and 23% respectively.

Effect of air pollution on plant life in the city of Chittagong, Bangladesh

Bangladesh faces a serious problem with air pollution, which has a negative impact on human health and tree health. Leaf damage, slow development, and decreased photosynthetic activity are just a few of the harmful effects on trees that have been linked to high concentrations of pollutants such as particulate matter, sulfur dioxide, and nitrogen oxides. These consequences affect the aesthetic value of green spaces in addition to interfering with the functions of the ecosystem that trees offer, such as air filtration and carbon sequestration. Given the seriousness of the problem, the present study plan was implemented to evaluate the amount of pollutants such as SOx, NOx, O3, hydrocarbons, particulate matter 2.5, particulate matter 10 and suspended particulate matter in the air in several urban areas of Chittagong and to evaluate the amount of chlorophyll from the leaves of affected and without affected leaves so that it may understand how the photosynthesis process of plants is interrupted by air pollution. 2 Number Gate Circle, Akbarsha Lane Circle, Alongkar Mor Bus Stop, Barik Building Circle, BDR Field Circle, Halishahar Access Road, Artillery Center-North Halishahar, Bangladesh Forest Research Institute and CRB Circle were selected as sampling location based on their heavy traffic and crowdedness. For the analysis of chlorophyll, each plant leaves were collected in three sections such as unaffected, slightly affected, and affected for comparison. The data studied showed that the most polluted zone with particulate matter had a lower chlorophyll concentration in the surrounding tree leaves. This can indicate that particulate matter can hinder photosynthesis reactions.

Innovative Design and Implementation of Portable and Rechargeable Air Purifier and Humidifier

This study presents the innovative design and successful implementation of a Portable and Rechargeable Air Purifier and Humidifier (PRAPH) aimed at addressing indoor air quality issues in Uganda. The device combines air purification and humidification functionalities into a compact, user-friendly, and energy-efficient unit. The design phase of the PRA-PH involved a thorough analysis of existing air purifiers and humidifiers, identifying key limitations such as limited portability, energy inefficiency, and complex maintenance requirements. The system incorporates high-efficiency particulate air (HEPA) filters, activated carbon filters, and ultrasonic humidification technology to effectively remove particulate matter, allergens, and airborne contaminants while simultaneously maintaining optimal humidity levels. A rechargeable lithium-ion battery was integrated to ensure portability, enabling users to use the PRA-PH without relying on a constant power source. Additionally, smart sensors and microcontroller-based control systems were employed to automate the device's operation, adjusting purification and humidification settings based on real-time air quality measurements. The PRA-PH was subjected to rigorous testing to evaluate its efficiency in purifying air and maintaining suitable humidity levels across various indoor environments. The results demonstrated significant improvements in air quality, showcasing the device's ability to effectively remove pollutants and maintain a comfortable humidity range. This study contributes to a portable and rechargeable air purifier and humidifier system that addresses the limitations of existing solutions. The PRA-PH's innovative design, efficient operation, and user-friendly interface make it a promising option for individuals seeking a convenient and effective way to improve indoor air quality and enhance the overall well-being of Ugandans.

CARCINOGENIC EFFECT OF VARIOUS TYPES OF SMOKE

All types of smoke are carcinogenic. Increasing air smoke is a serious global problem. Knowledge on carcinogenic effects of various types of smoke is necessary to work out effective preventive measures.&#x0D; The purpose of the review is to characterize the general characteristics and peculiarities of the carcinogenic effects of various types of smoke. The most significant carcinogens of all types of smoke are polycyclic aromatic hydrocarbons, heavy metals and carbon microparticles. Any smoke is an etiological factor for respiratory tract cancer, and systemic neoplasms (tumors of hematopoietic and lymphoid tissues, central and peripheral nervous systems, soft tissues and skeleton). Tobacco smoke may be involved in the pathogenesis of cervical cancer due to the induction of local immunosuppression and specific tropic nitrosamines. Exhaust fumes due to high benzene content may cause hematological malignancies, especially leukemia in children. Wildfire smoke, due to significant amounts of ultra-fine carbon particles PM0.1, contributes to the development of central nervous system tumors. Severe contamination with natural and artificial radionuclides makes wildfire smoke a factor of high carcinogenic danger for the human population globally. Prevention of malignant neoplasms caused by smoke requires government measures to promote smoking cessation, hybrid and electric engines in automobiles, as well as wildfire prevention, early detection and extinction. Effective respirators and indoor air filters should be used for personal protection. To relieve environmentally caused oxidative stress, herbal medicines and food products that stimulate autophagy, as well as transfer factors for immunodeficiency correction, are recommended.

In-situ polarized coaxial PVDF/PL nanofiber filtration membrane with high efficiency, low resistance and antimicrobial properties

Aerosols are prone to breed bacteria on air filtration materials so as to cause secondary air pollution, especially carrying bacteria and viruses. This paper utilized coaxial electrospinning technology with traditional Chinese medicine Physalis alkekengi Linn as the core layer antibacterial material and polyvinylidene fluoride/polyacrylonitrile mixed solution as the shell layer material. Nonsolvent phase separation technology was employed to prepare the porous shell layer, achieving sustained slow-release and long-lasting antibacterial effects from the core P. alkekengi Linn. In addition, an in-situ polarization technology from high voltage in electrospinning process was adopted to achieve permanent polarization of polyvinylidene fluoride, which changed from α-crystal to β-crystal. Using the electrostatic charge adsorption effect and the ultra-fine pore size screening of the nanofiber membrane, high-efficiency and low-resistance filtration of aerosols above 0.3 μm was achieved (99.98% filtration efficiency and filtration resistance less than 25 Pa). It can be widely used in the field of air filtration and protection in high-risk environments such as stations, schools, and hospitals, achieving long-lasting antibacterial, high-efficiency, and low-resistance air filtration and protection.

Electrospun 3D Curly Electret Nanofiber Air Filters for Particulate Pollutants

Amidst rapid industrialization and urbanization, air pollution has emerged as a global environmental challenge. Traditional air filtration materials face challenges in effectively filtering PM0.3 and often result in discomfort due to high air resistance when used for personal protection, as well as excessive energy consumption in industrial air purification applications. This study initially utilized extremely high environmental humidity to induce fiber formation, resulting in the preparation of a fluffy fiber membrane with a three-dimensional curly morphology, which increased the porosity to 96.93%, significantly reducing air resistance during filtration. Subsequently, rutile TiO2 with a high dielectric constant was introduced, exploiting the low pressure drop characteristic of the fluffy 3D curly fiber membrane combined with the electret effect of TiO2 nanoparticles to notably improve the issue of excessive pressure drops while maintaining filtration efficiency. The microstructure, morphology, and element distribution of the fibers were analyzed using FESEM and EDS. FTIR and XRD were employed to examine the functional groups and crystal structure within the fibers. The electret effect and filtration performance of the fiber membrane were investigated using an electrostatic tester and a particulate filtration efficiency tester. The results demonstrated that inducing fiber formation under high-humidity conditions could produce fibers with a 3D curly structure. The fiber membrane was highly fluffy, significantly reducing the pressure drop. Introducing an appropriate amount of titanium dioxide markedly improved the electrostatic effect of the fiber membrane, enhancing the filtration performance of the 3D curly PVDF/TiO2 composite fiber membrane. With a 0.5% addition of TiO2 nanoparticles, the filtration efficiency of the fiber membrane reached approximately 99.197%, with a pressure drop of about 49.83 Pa. This study offers a new approach to developing efficient, low-resistance air filtration materials, showcasing the potential of material innovation in addressing air quality challenges within the sustainable development framework.

Algorithm for Point Cloud Dust Filtering of LiDAR for Autonomous Vehicles in Mining Area

With the continuous development of the transformation of the “smart mine” in the mineral industry, the use of sensors in autonomous trucks has become very common. However, the driving of trucks causes the point cloud collected by through Light Detection and Ranging (LiDAR) to contain dust points, leading to a significant decline in its detection performance, which makes it easy for vehicles to have failures at the perceptual level. In order to solve this problem, this study proposes a LiDAR point cloud denoising method for the quantitative analysis of laser reflection intensity and spatial structure. This method uses laser reflectivity as the benchmark template, constructs the initial confidence level template and initially screens out the sparse dust point cloud. The results are analyzed through the Euclidean distance of adjacent points, and the confidence level in the corresponding template is reduced for rescreening. The experimental results show that our method can significantly filter dust point cloud particles while retaining the rich environmental information of data. The computational load caused by filtering is far lower than that of other methods, and the overall operation efficiency of the system has no significant delay.

Secondhand smoke Infiltration in multiunit housing: Health effects and nicotine levels

IntroductionApproximately 46% of U.S. multiunit housing residents with smoke-free home rules, 29 million persons, experience secondhand smoke infiltration in their apartments. Federal health authorities warn that secondhand smoke exposure in multiunit housing is detrimental to the health of children and nonsmoking adults. However, none of the 50 U.S. States bans smoking in privately-owned multiunit housing, and less than 0.1% of the 91,000 U.S. municipalities do. Materials and methodsThis study investigates the health problems reported by 162 nonsmoking residents residing in 104 multiunit apartments in 71 municipalities in 19 U.S. States and the District of Columbia, plus 2 Canadian Provinces. Smoke infiltration was confirmed for residents of 103 nonsmoking apartments using self-deployed passive nicotine monitors from 2006 to 2023. Another five subjects reported health problems from marijuana smoke infiltration confirmed by self-administered marijuana surface wipe tests. The secondhand smoke levels in smokers’ units are estimated using mathematical modeling. ResultsNonsmokers complained of eye, nose, throat, and lung irritation, headache, dizziness, nausea, difficulty in breathing, tachycardia, and asthmatic attacks as well as malodors. Many sought medical care and some were hospitalized. Some regarded their apartments as uninhabitable. About 12% resorted to litigation. Nicotine concentrations in subjects’ apartments ranged from 0.001 to 6.60 µg/m3 (geometric mean, 0.028 µg/m3). Modeled PM2.5 levels for a typical smoker’s apartment estimated air pollution levels ranging from “Very Unhealthy” to “Hazardous” levels of the U.S. Air Quality Index. Marijuana surface wipe tests in 5 units showed Tetrahydrocannabinol (THC) ranging from 1.25 µg/m2 to 6.92 µg/m2. Reported health effects were similar to those with tobacco complaints. ConclusionsSecondhand smoke infiltration from smokers’ apartments into nonsmokers’ apartment units in multiunit housing can provoke major morbidity for nonsmoking residents. Nonsmokers’ efforts to eliminate infiltration by sealing of cracks, air cleaning, or increased ventilation proved futile. Building owners and managers need to be educated about protecting nonsmoking residents’ health and welfare from secondhand smoke infiltration. Smoking of tobacco and marijuana products in multiunit housing should be banned.

Silk-crosslinked polyester fibrous air filters with electrostatic interfacial mediation for high- efficiency and low-resistance air purification

Silk-crosslinked polyester fibrous air filters with electrostatic interfacial mediation for high- efficiency and low-resistance air purification