Canopy Hood Research Articles

Simulation Study of the Capture and Purification Performance of Exhaust Fume Systems in Chinese Commercial Kitchens—Case Study in Tianjin

A Chinese commercial kitchen fume exhaust (CCKEF) system mainly consists of a wall-mounted canopy hood, air duct and terminal electrostatic purifiers, the capture and purification performance of which should be guaranteed to obtain satisfactory indoor and outdoor air environment in engineering applications. However, few studies have focused on the operation performance of CCKEF systems. This study was aimed at providing a simulation method to investigate the operation performance of such systems. The simulation model of a representative CCKEF system was established using CFD software and validated with measured temperature, air velocity and purification efficiency with a deviation within 10%. The validated model was used to predict the indoor air environment and purification efficiency of the CCKEF system under different working conditions. The results showed that the temperature of transfer air from adjacent rooms had a greater impact on the thermal environment of the cooking area than the surface temperature of stoves. The exhaust air volume had a significant influence on both the indoor air environment and purification efficiency. CCKEF system was suggested to be operated at the optimum airflow according to the simultaneous coefficient of stoves as the energy consumption of the system can be saved by 3.75%.

Clinical evaluation of the new indirect calorimeter in canopy and face mask mode for energy expenditure measurement in spontaneously breathing patients

The new indirect calorimeter developed in the framework of the ICALIC project was first evaluated in ventilation mode. This second phase aimed to compare its ease of use and precision with another commonly used device in spontaneously breathing adult patients using a canopy hood or a face mask. The time required to measure resting energy expenditure (REE) with Q-NRG® in canopy and face mask mode was compared with Quark RMR® in canopy mode by sequential measurements in 45 and 40 spontaneously breathing adult patients, respectively. Their precision was assessed at different time intervals, using coefficients of variation (CV%) and repeated measures one-way ANOVA. Agreement between the two devices was evaluated by correlation coefficients, Bland-Altman plots, and paired t-test. Patients' characteristics potentially affecting the measurement were assessed using linear regression analysis. REE measurement with Q-NRG® was faster than Quark RMR® (19.7±2.9min vs 24.5±4.3min, P<0.001). In canopy mode, Q-NRG® gave values similar to Quark RMR®, with 73% of patients achieving a steady state (CV% <10%) within the 5-15min interval. In face mask mode, Q-NRG® was less stable than Quark RMR® in canopy mode, and steady state was achieved in only 40% of the patients within the 5-15min interval. Correlation between the two devices was stronger when Q-NRG® was used in canopy than in face mask mode, with Pearson coefficients of 0.96 and 0.86, respectively. Compared to Quark RMR® in canopy mode, systematic bias±1.96∗SD with Q-NRG® was-14±236kcal/day in canopy and 73±484kcal/day in face mask mode. Q-NRG® in face mask mode overestimated REE by 150±51kcal/day in men compared to Quark RMR® in canopy mode. Q-NRG® in canopy mode made it possible to save at least 5min compared to Quark RMR® while maintaining the same measurement precision. However, its use in face mask mode could lead to REE overestimation in men and, therefore, should not be recommended in the clinical setting. ClinicalTrials.gov no. NCT03947294.

Evaluation of a novel curved vortex exhaust system for pollutant removal

Based on the principle of a column air vortex, a novel curved vortex exhaust system (CVES) is proposed in this study as an alternative for capturing pollutants when a canopy hood cannot be used. Experimental and numerical methods are used to investigate the curved vortex formation process and influencing factors of the CVES, and the effect of geometric parameters and the supply/exhaust flow ratios are investigated to optimise the pollutant capture performance. The evolution of the negative pressure distribution is used to investigate the formation process of the vortex in the CVES. The formation of the curved vortex in the CVES is found to be a top-to-bottom process, and there is a delay of a few seconds before the curved vortex is formed. According to the characteristics of the CVES, the effective pollution source area is proposed as an index to evaluate the performance of the CVES, and the effects of the arc baffle width, back plate angle, exhaust outlet position, and exhaust outlet area on the vortex flow characteristics and effective pollution source area are analysed. The relationship between the supply/exhaust flow ratio and size of the effective pollution source area is investigated with different exhaust outlet flowrates. The results reveal that with an increase in the exhaust outlet flowrate, the optimal supply/exhaust flow ratio of the CVES gradually decreases from 0.4 to 0.2 and then remains stable. Meanwhile, a larger ventilation flowrate is beneficial for increasing the size of the effective pollution source area.

Technical control of nanoparticle emissions from desktop 3D printing.

Material extrusion (ME) desktop 3D printing is known to strongly emit nanoparticles (NP), and the need for risk management has been recognized widely. Four different engineering control measures were studied in real-life office conditions by means of online NP measurements and indoor aerosol modeling. The studied engineering control measures were general ventilation, local exhaust ventilation (LEV), retrofitted enclosure, and retrofitted enclosure with LEV. Efficiency between different control measures was compared based on particle number and surface area (SA) concentrations from which SA concentration was found to be more reliable. The study found out that for regular or long-time use of ME desktop 3D printers, the general ventilation is not sufficient control measure for NP emissions. Also, the LEV with canopy hood attached above the 3D printer did not control the emission remarkably and successful position of the hood in relation to the nozzle was found challenging. Retrofitted enclosure attached to the LEV reduced the NP emissions 96% based on SA concentration. Retrofitted enclosure is nearly as efficient as enclosure attached to the LEV (reduction of 89% based on SA concentration) but may be considered more practical solution than enclosure with LEV.

Flow-field evolution and vortex structure characteristics of a high-temperature buoyant jet

High-temperature buoyant jets generally exist at the exhaust port during the casting process. Canopy hoods are employed to capture these jets in industrial plants. However, because of the lack of flow-field evolution and vortex structure characteristics of the buoyant jets, the optimal design of canopy hood is lack of guidance. In this study, the effects of different initial temperatures (T0) of buoyant jets on the evolution of the temperature, velocity, and vorticity magnitude fields and vortex structure characteristics were studied by large-eddy simulation. The results showed that for 100–1200 °C buoyant jets, the contracted section, which is useful in determining the preferred canopy hood installation position, is generated within 0.7–2 times the source diameter from the nozzle (Z/D). As T0 increases, the position of the contracted section tends to come closer to the nozzle, and the space height for temperature attenuation in the core region is reduced. The contracted section formation results from the rupture of the vortex ring. Because the vortex ring can restrict the diffusion of the buoyant jet, the initial temperature has little effect on the diffusion angle within 4 Z/D. In addition, the spiral vortex structure entrains a large quantity of ambient air, which causes the exhaust flow rate to increase sharply. These conclusions may guide for the design of the exhaust hood installation height for high-temperature buoyant jets to achieve energy savings.

Clinical determinants of resting metabolic rate in geriatric outpatients

PurposeAccurate estimation of the energy requirements including resting metabolic rate (RMR) is important for optimal nutritional care, yet its clinical determinants are unknown. This study examined the associations between clinical determinants of the Comprehensive Geriatric Assessment (CGA) domains with RMR among geriatric outpatients. Materials & methodsData were retrieved from cohorts of community-dwelling older adults (n = 84, 54 female) referring to geriatrics outpatient mobility clinics in both Amsterdam, The Netherlands and Melbourne, Australia. Determinants within domains of the CGA included diseases (number, type and severity of diseases, polypharmacy), nutrition (body weight, body mass index, absolute and relative skeletal muscle mass, fat-free mass and fat mass, risk of malnutrition), physical function (handgrip strength, Short Physical Performance Battery, Timed Up & Go), cognition (Mini-Mental State Examination), psychological wellbeing (Geriatric Depression Scale) and blood pressure. RMR was objectively measured using indirect calorimetry with a canopy hood. Association between the clinical determinants with standardized RMR (country and sex-specific z-score) were analysed with linear regression adjusted for age, sex and body weight. ResultsDeterminants within the nutritional domain were associated with RMR; body weight showed the strongest association with RMR. Significant associations between determinants within the nutritional domain with RMR disappeared after further adjustment for body weight. None of the other domains were associated with RMR. ConclusionsBody weight is the strongest clinical determinant of RMR and should be taken into account when estimating RMR in geriatric care.

Survey study on Chinese commercial kitchen exhaust fume systems in Tianjin

Exhaust fume system plays an important role in ensuring indoor and outdoor environment in the Chinese commercial kitchens (CCKs). To investigate the current status of exhaust fume systems in CCKs (CCKEF), on-site survey of cooking appliances, components of CCKEF including exhaust hoods, purification equipment, exhaust fans, discharge form and replacement air, outdoor grease accumulation, and indoor environment, was conducted in 41 CCKs in Tianjin. Results showed that: (1) the diversity and number of cooking appliances was related to kitchen area. 76.19% of stir-frying stoves were located at the end of the appliance lines. (2) Most of the CCKEFs were composed of wall-mounted canopy hood (94.12%), terminal static purifier (98.04%), centrifugal fan (100%), roof-located discharge (66.67%) and transfer air (100%). 47.06% of canopy hoods were equipped with baffle filters, including 29.41% tube-type, 9.80% plate-type and 7.85% strainer-type. The nameplate purification efficiency of purifiers met the fume emission standard. 81.08% of purifier manufacturers were from Beijing. (3) Outdoor grease accumulation was serious. 72.73% had much or a lot of grease accumulation. Cleaning period and the number of burners were the major influence factors. For systems with over 4 burners, the cleaning period was better within 2 months. (4) 70.8% of chefs were dissatisfied with the thermal comfort in CCKs. Thermal and wet sensation varied with seasons and summer was the most unsatisfactory season. Over 80.0% of chefs felt fumes overflowing and interfering noise. The indoor environment in CCKs needed improvement. Survey results can provide reference for the designing of CCKEF in China.

휘발성 유기용제 취급 사업장의 위해성평가 및 위해저감 방안 수립 연구

Although several studies have reported the detrimental effects of volatile organic solvents, workers of solvent ink manufacturers who are involved in producing them have been producing them in the absence of specific management or regulation due to a lack of cost-effectiveness and risk analysis. With the application of the system of the Chemical management systems, this study selected a total of 5 types of chemicals such as PMAc, CH, BGAc, DMDG and GBL that should be managed. The amount of the emission of air pollutants contained in the selected chemicals. In addition, DNEL of each raw material was calculated with the use of its NOAEL values. Thus, the degree of detrimental effects on humans were evaluated. The result was that the concentration of the emission of BGAc in humans was found to be possibility of the effects of chronic inhalation toxicity. The replacement of a hand pump in the manufacturing process and a canopy hood with a lateral aspiration one were proposed as the essential methods for improving the safety for the reduction.

Abstract P211: Increased Salt Intake Decreases Postprandial Energy Expenditure in Healthy Volunteers - A Randomized Clinical Study

High salt intake is a potential risk factor for obesity independent of energy intake, though underlying mechanisms remain unclear. Diet-induced thermogenesis (DIT) accounts for about 10% of total energy expenditure. We hypothesized that high salt intake decreases DIT in healthy volunteers. We enrolled 40 healthy subjects (sex ratio 1:1) in a randomized, double-blind, placebo-controlled, parallel-group study (NCT03024567). They received either 6 g salt or placebo daily in capsules over 14 days on top of their habitual diet. Before and after the intervention, resting and postprandial energy expenditure, ambulatory blood pressure, bioelectrical impedance analysis (BIA), and food intake from 3-day food records were obtained. Energy expenditure was measured by indirect calorimetry (canopy hood) after a 12h overnight fast and a standardized 440 kcal, high-protein meal. In both groups, 19 subjects completed the study (placebo: nine men, 29 ± 6 years, BMI 23.1 ± 0.5 kg/m 2 ; salt: ten men, 32 ± 7 years, BMI 23.3 ± 0.7 kg/m 2 ). Salt intake from foods was 6 g/d in both groups, both before and after the intervention. Resting energy expenditure did not change in either group. DIT was significantly decreased after salt ( P = 0.049) but not after placebo ( NS ). Decreased DIT was accompanied by a decreased fat and therefore increased carbohydrate oxidation after salt ( P = 0.03). However, this was also the case after placebo ( P &lt; 0.0001). Surprisingly, systolic blood pressure was increased in four and 11 subjects after salt and placebo, respectively (both NS ). Diastolic blood pressure was higher in seven subjects, both after salt and placebo (both NS ). Body composition and hydration did not change due to increased salt intake or placebo. In conclusion, a moderate short-term increase of salt intake decreased the thermic effect of a high-protein meal. This could contribute to the observed weight gain in populations consuming a Western diet high in salt.

Effective management of spasticity and impacts on weight change and resting energy expenditure in a female with spinal cord injury: a case report

The impact of muscle spasticity on weight change and energy expenditure after spinal cord injury (SCI) is not well understood. This case study reports changes to body weight and resting energy expenditure (REE) in a 36-year-old female (T3 AIS A SCI; 80 kg; body mass index=28 kg m-2 at injury) requiring escalating therapies to manage severe spasticity. Body weight, spasticity medications and fasted REE (measured using indirect calorimetry, canopy hood) were recorded at 4, 16, 17, 20 and 44 months post injury. Spasticity was assessed at each time point using the Modified Ashworth Scale (MAS). At 4 months post injury, REE was high (1710 kcal per day) corresponding with severe spasticity in the lower limbs (4 on the MAS). Over the following 12 months, the patient experienced an 8 kg weight loss, visible lower limb muscle wasting and a 30% reduction in REE while requiring increasing drug therapies for spasticity. With insertion of an intrathecal Baclofen pump at 17 months and cessation of other medications, spasticity improved markedly and weight increased by 6 kg in 27 months without any significant change to REE (mean=1260 kcal±2%). Effective management of spasticity with intrathecal Baclofen appears to be associated with weight gain but not REE. Without body composition and activity energy expenditure data, this observation is difficult to explain. Regardless, routine weight monitoring with appropriate dietary counselling should be considered in this patient group to help prevent unintentional weight gain.

C&C efficiency of canopy hood exposed to horizontal air stream in commercial kitchen calculated by CFD analysis

ABSTRACTAs one of the commercial kitchen ventilation researches, the mechanism of capture phenomenon and containment one of a canopy hood has to be investigated. Several experiments intended to change the Capture and Containment (C&C) efficiency of combustion gas and cooking effluence were conducted under the conditions of different suction wind velocity at the bottom of a hood, sometimes called face velocity, which is caused by the different hood size. The overall C&C efficiency was analyzed by means of computational fluid dynamics (CFD). The C&C efficiency from the experiment and CFD analysis showed good agreement, and it was assumed that the disturbing ambient airflow around the hood can influence on the C&C efficiency. Therefore the kitchen space was assumed which includes the disturbing airflow over the counter between a dining hall and a kitchen. As a result, the C&C efficiency of the larger hood decreased more under the disturbing airflow.

Application of computational fluid dynamics for solving ventilation problems in metallurgical industrial processes

ABSTRACTThis paper focuses on the application of computational fluid dynamics (CFD) modelling to solve challenging ventilation problems during metallurgical industrial process events. Three application case studies are presented, including a local fume capture hood modelling study to verify the design modifications, a canopy hood study to identify the ventilation improvement solution and a study for troubleshooting and design modification of a large furnace building ventilation system. These case studies involved various heat and fume sources, complicated geometry and the interaction of natural buoyancy and mechanical exhaust. The studies suggested that site measurement and video analysis are important in obtaining realistic and representative model boundary conditions. The selection of transient or steady-state simulations should be based on the actual operating modes and the associated fume transport physics. The results of these studies demonstrate that CFD can be used to effectively verify the ventilation design alternatives, troubleshoot the operating problems and achieve cost-effective design solutions.

Feasibility and Acceptability of Implementing Indirect Calorimetry Into Routine Clinical Care of Patients With Spinal Cord Injury.

Background: In the absence of reliable predictive equations, indirect calorimetry (IC) remains the gold standard for assessing energy requirements after spinal cord injury (SCI), but it is typically confined to a research setting. The purpose of this study is to assess the feasibility and acceptability of implementing IC into routine clinical care in an Australian SCI rehabilitation facility. Methods: Bedside IC (canopy hood) was performed, and patients completed an IC acceptability questionnaire (open-ended; yes/no; 5-point Likert scale). Fasted resting energy expenditure (REE) steady-state criteria were applied to assess data quality, and adherence to a test ≥20 minutes was recorded. Staff were surveyed to assess impact of IC on usual care. Results: Of 35 eligible patients, 9 declined (7 reported claustrophobia). One patient could not be tested before discharge and 25 underwent IC (84% male, injury level C2-L2, AIS A-D). Anxiety prevented one patient from completing IC, while another failed to fast. The remaining 23 patients achieved a steady-state REE (≥5 consecutive minutes with ≤10% coefficient of variation for VO2 and VCO2). Test-retest (n = 5) showed <10% variation in REE. Patients deemed the procedure acceptable, with 88% reporting a willingness to repeat IC. Eighty percent of patients and 90% of staff agreed it was acceptable for IC to be integrated into usual care. Conclusion: This study found that IC is a feasible and acceptable addition to the routine clinical care of patients recovering from SCI and may serve to improve accuracy of nutrition interventions for this patient population.

산화알루미늄 섬유와 니켈분말 후처리공정에서 입자의 노출특성

Objectives: Nanomaterials have been used in various fields. As use of nanoproducts is increasing, workers dealing with nanomaterials are also gradually increasing. Exposure assessments for nanomaterials have been carried out for protection of worker`s health in workplace. Exposure studies were mainly focused on manufacturing processes, but these studies on after-treatment processes such as refinement, weighing, and packing were insufficient. So, we investigated exposure characteristics of particles during after-treatment processes of fibers and Ni powders. Methods: Mass-production of Ni powder process was carried out in enclosed capture-type canopy hood. In a developing stage, was handled with a local ventilation unit. Exposure characteristics of particles were investigated for fiber and Ni powder processes during the periods of 10:00 to 16:00, 20 May 2014 and 13:00 to 16:00, 21 May 2014, respectively. Three real-time aerosol instruments were utilized in exposure assessment. A scanning mobility particle sizer(SMPS, nanoscan, model 3910, TSI) and an optical particle counter(OPC, portable aerosol spectrometer, model 1.109, Grimm) were used to determine the particle size distribution in the size range of 10-420 nm and , respectively. In addition, a nanoparticle aerosol monitor(NAM, model 9000, TSI) was used to measure lung-deposited nanoparticle surface area. Membrane filters(isopore membrane filter, pore size of 100 nm) were also used for air sampling for the FE-SEM(model S-5000H, Hitachi) analysis using a personal sampling pump(model GilAir Plus by 2.5 L/min, Gilian). Conclusions: For Ni powder after-treatment process, only 27% increase in particle concentration was found during the process. However, for fiber after-treatment process, significant exposure(1.56-3.34 times) was observed during the process.

A Study on the Improvement of Ventilation Rate Using Air-flow Inducing Local Exhaust Ventilation System

In the case of the canopy hood, which is one of the existing Local Exhaust Ventilation systems, there appears to be a weakness in that when the level of ventilation is insufficient or when the effluent′s buoyancy effect is significant, a partial amount of effluent seeps out and accumulates on the upper workspace. This study proposes the Air-flow Inducing Local Exhaust Ventilation system (AI-LEV), which can increase the ventilation rate without increasing the use of artificial energy by extracting the high-heat or high-density effluent that accumulates on the upper workspace. CFD (Computational Fluid Dynamics) was used to examine the effectiveness of the AI-LEV. The thermal characteristics of the mock-up chamber, along with the introduction of the canopy hood, was examined and the physical reproducibility of the CFD was verified experimentally. Compared to the existing Local Exhaust Ventilation systems, the introduction of AI-LEV led to a radical decrease in temperature through the overall interior. In addition, the high-temperature air that accumulated in the chamber′s upper space was extracted smoothly outside the chamber through the inducement of the AI-LEV. The AI-LEV showed a 0.5-1.8 ºC decrease in temperature in a space larger than 1.5m from the floor compared to the existing Local Exhaust Ventilation systems.

Performance of particulate containment at nanotechnology workplaces

The evaluation of engineering controls for the production or use of carbon nanotubes (CNTs) was investigated at two facilities. These controls assessments are necessary to evaluate the current status of control performance and to develop proper control strategies for these workplaces. The control systems evaluated in these studies included ventilated enclosures, exterior hoods, and exhaust filtration systems. Activity-based monitoring with direct-reading instruments and filter sampling for microscopy analysis were used to evaluate the effectiveness of control measures at study sites. Our study results showed that weighing CNTs inside the biological safety cabinet can have a 37% reduction on the particle concentration in the worker's breathing zone, and produce a 42% lower area concentration outside the enclosure. The ventilated enclosures used to reduce fugitive emissions from the production furnaces exhibited good containment characteristics when closed, but they failed to contain emissions effectively when opened during product removal/harvesting. The exhaust filtration systems employed for exhausting these ventilated enclosures did not provide promised collection efficiencies for removing engineered nanomaterials from furnace exhaust. The exterior hoods were found to be a challenge for controlling emissions from machining nanocomposites: the downdraft hood effectively contained and removed particles released from the manual cutting process, but using the canopy hood for powered cutting of nanocomposites created 15%-20% higher ultrafine (<500 nm) particle concentrations at the source and at the worker's breathing zone. The microscopy analysis showed that CNTs can only be found at production sources but not at the worker breathing zones during the tasks monitored.

Evaluation of a new whole room indirect calorimeter for measurement of resting metabolic rate

ObjectiveCompare a new whole room indirect calorimeter (WRIC) for measuring resting metabolic rate (RMR) against a metabolic cart (MC).MethodsSimulated RMR (kcal/d), RQ (VCO2/VO2) and air flow (L/min) were obtained by performing 10 one‐hour propane (99.5% purity) combustion tests within the new WRIC (Promethion GA‐6 and FG‐1, Sable Systems Intl, Las Vegas, NV) and then with a MC (Vmax Encore, Carefusion Inc, San Diego, CA) utilizing a modified canopy hood. The propane was weighed before and after each test. Both the WRIC and MC were calibrated prior to each test according to the respective manufacturer's instructions. Calculated RMR and RQ from propane combustion were compared to simulated metabolic values. All data were extrapolated to 24‐hours and analyzed using SPSS (Ver.13).ResultsCalculated and simulated RMR for the WRIC ranged from 1861.4 to 3021.1 and 1828.2 to 3067.8 while that for the MC were 1450.6 to 2082.6 and 1353.6 to 2304.0, respectively. RQ for the WRIC and MC from propane ranged from 0.59 to 0.62 and 0.57 to 0.60, respectively. Compared to propane simulated RMR for the WRIC and MC varied by 0.80±1.5 and 2.0±8.8%, respectively. However, in comparison to calculated individual values, there was greater variability of simulated RMR (−10.8 to +13.1%) across the 10 propane combustion tests for the MC versus that for the WRIC (−1.6 to 2.3%). Finally, air flow for the WRIC and MC were 98.95 ± 0.38 and 44.40 ± 1.50, respectively.ConclusionsThe WRIC was more precise than the MC. The imprecision of the MC may contribute to intermittent large errors of RMR thus possibly effecting outcomes when used for calorie prescription.

용해공정의 캐노피 후드 성능 개선에 관한 수치 해석적 연구

This study reviewed the capturing performance of a canopy hood used in some melting processes of a casting manufacturing factory through a site survey. In addition, this study compared and evaluated the flow field and pressure field for the plans to enhance the hazardous air pollutants collection capacity by using CFD model. The case-2(flange attached + double hood) can be improved in terms of collection performance, but is expected to increase in hood static pressure by about 70% more than the existing structure, so it was shown that its site applicability is not good. It is judged that the shape of case-3(flange attached + double cone attached) is most suitable to improve the suction efficiency. This is because a double cone is installed at the center of the opening to concentrate the flow rate on the edge of the hood and control the hume rising to the center of the hood without a static pressure rise via the slope of the cone.

Performance of Canopy Hood and Radiative Heat Generation from Low-Radiation Cooking Equipment with Concentrated Exhaust Chimney

Performance of Canopy Hood and Radiative Heat Generation from Low-Radiation Cooking Equipment with Concentrated Exhaust Chimney

Different Types and Settings of Kitchen Canopy Hoods and Particulate Exposure Conditions during Pan-frying of Beefsteak

The aim of this study was to compare four different kinds of canopy hoods in common use in private Norwegian households, in regard to their ability to protect the cook from exposure to particles from cooking fumes and to reduce the spreading of fume particles in the kitchen. The hoods were tested during pan-frying of beefsteak under different combinations of the following parameters: medium or maximum flow rate in the hood, two different heights above the stove and three different locations in the kitchen. The mass concentration of total particles in the breathing zone of the cook and the number concentration of particles in the size interval 0.3—0.5 μm in the kitchen was measured. To achieve the best possible effect of a kitchen canopy hood under the conditions described, it is best to mount it in a corner with a 60 cm distance to the stove and run it on the maximum flow rate. Also, it is best to install hoods that extract the polluted air out of the house rather than recycling it through a charcoal filter.