Degradation of Selected Indoor Air Pollutants:Comparison Study of Photocatalytic,Ozone-Assisted Photocatalytic and Amine Adsorption Processes

Indoor air pollutants impact human health,comfort and productivity.The method of photocatalysis has been applied mainly in flow reactors and little information is available on indoor air pollutant removal in airtight reactors.In the paper,experiments were carried out to remove formaldehyde(HCHO),ammonia(NH_3) and volatile organic compounds(VOCs)in the airtight and ventilated chambers.Results demonstrated that 90.4%of HCHO,92.3%of NH_3 and 57.9%of VOCs were removed in the amine adsorption process,while 67.5% (hereinbefore,these are the mass fraction)of HCHO,60.0%of NH_3,and 61.2%of VOCs were removed in the photocatalytic process.However,ozone-assisted photocatalytic process showed great potential to degrade indoor air pollutants in the ventilated chamber.Factors and mechanisms of the photocatalytic degradation of HCHO, NH_3 and VOCs were also discussed.

Indoor Air Pollution and Its Determinants in Household Settings in Jaipur, India

Individuals spend 90% of their time indoors, primarily at home or at work. Indoor environmental factors have a significant impact on human well-being. It was a longitudinal study that assessed the major factors that reduce indoor air quality, namely particulate matter, and bio-aerosols, using low-cost sensors and the settle plate method, respectively also to determine the effect of atmospheric parameters and land use patterns in households of commercial, industrial, residential, slum, and rural areas of the city. PM2.5 concentration levels were similar in most parts of the day across all sites. PM10.0 concentration levels increased indoors in a commercial area. PM2.5 concentration showed a negative correlation with temperature and a positive correlation with relative humidity in some areas. Very high values of PM2.5 concentration and PM10.0 concentration have been observed in this study, inside households of selected rural and urban areas. Pathogenic gram-positive cocci, gram-positive rods, Aspergillus, and Mucor species were the most common bacterial and fungal species respectively found inside households. This study examined particulate matter concentration along with bio-aerosols, as very less studies have been conducted in Jaipur the capital of Rajasthan, a state in the western part of India which assessed both of these factors together to determine the indoor air quality. Rural households surrounding the periphery of the city were found to have similar pollution levels as urban households. So, this study may form the basis for reducing pollution inside households and also for taking suitable measures for the reduction of pollution in the indoor environment.

An extended analysis of cardiovascular benefits of indoor air filtration intervention among elderly:a randomized crossover trial(Beijing indoor air purifier study,BIAPSY)

Objective Evidence on potential cardiovascular benefits of personal-level intervention among the elderly exposed to high levels of particulate matter(PM)remains limited.We aimed to assess improvements in surrogate markers of cardiovascular injury in vulnerable populations at risks by using indoor air filtration units.Methods We conducted a randomized crossover trial for 2 separate 2-week air filtration interventions in 20 households of patients with stable chronic obstructive pulmonary disease and their partners in the winter of 2013,with concurrent measurements of indoor PM.The changes in biomarkers indicative of cardiac injury,atherosclerosis progression and systemic inflammation following intervention were evaluated using linear mixed-effect models.Results In the analysis,average levels of indoor PM with aerodynamic diameters<2.5µm(PM2.5)decreased significantly by 59.2%(from 59.6 to 24.3µg/m3,P<0.001)during the active air filtration.The reduction was accompanied by improvements in levels of high-sensitivity cardiac troponin I by−84.6%(95%confidence interval[CI]:−90.7 to−78.6),growth differentiation factor-15 by−48.1%(95%CI:−31.2 to−25.6),osteoprotegerin by−65.4%(95%CI:−56.5 to−18.7),interleukin-4 by−46.6%(95%CI:−62.3 to−31.0)and myeloperoxidase by−60.3%(95%CI:−83.7 to−3.0),respectively.Conclusion Indoor air filtration intervention may provide potential cardiovascular benefits in vulnerable populations at risks.

Natural Gas and Indoor Air Pollution: A Comparison With Coal Gas and Liquefied Petroleum Gas

Objective The study was designed to compare the combustion products of coal gas, liquefied petroleum gas and natural gas in relation to indoor air pollution. Methods Regular pollutants including B(a)P were monitored and 1-hydroxy pyrene were tested in urine of the enrolled subjects. Radon concentrations and their changes in four seasons were also monitored in the city natural gas from its source plant and transfer stations to final users. To analyze organic components of coal gas, liquefied petroleum gas and natural gas, a high-flow sampling device specially designed was used to collect their combustion products, and semi-volatile organic compounds contained in the particles were detected by gas chromatograph-mass spectrograph (GC/MS). Results Findings in the study showed that the regular indoor air pollutants particles and CO were all above the standard in winter when heating facilities were operated in the city, but they were lowest in kitchens using natural gas; furthermore, although NO2 and CO2 were slightly higher in natural gas, B(a)P concentration was lower in this group and 1-hydroxy pyrene was lowest in urine of the subjects exposed to natural gas. Organic compounds were more complicated in coal gas and liquefied petroleum gas than in natural gas. The concentration of radon in natural gas accounted for less than 1‰ of its effective dose contributing to indoor air pollution in Beijing households. Conclusion Compared to traditional fuels, gases are deemed as clean ones, and natural gas is shown to be cleaner than the other two gases.

Study on Model of Indoor Air Pollution Forecast for Decoration Under Natural Ventilation Condition

To establish the model of indoor air pollution forecast for decoration. Methods The model was based on the balance model for diffusing mass. Results The data between testing concentration and estimating concentration were compared. The maximal error was less than 30% and average error was 14.6%. Conclusion The model can easily predict whether the pollution for decoration exceeds the standard and how long the room is decorated.

CO and Particle Pollution of Indoor Air in Beijing and Its Elemental Analysis

Three representative types of houses in Beijing were selected and, in each type, smoking and nonsmoking households were compared. IP, RP. and CO concentrations in the living room and kitchen were monitored during each season. and the level of COHb in the heads of the households were measured. The study showed that indoor air pollution was rather severe, especially during winter. when paniculate concentrations markedly exceeded the standard and CO concentration was as high as 47 ppm. Indoor air pollution was closely related to the type of house, particularly to the mode of heating. In houses. of the same type, pollution improved greatly after central heating facilities were installed. Analysis of 30 elements revealed that pollution was typically caused by coal burning. aggravated by dusty wind, but high indoor Pb levels were probably due to the use of LPG for cooking. In our study the effect of cigarette smoking was sometimes masked by the severe indoor pollution. (C)1990 Academic Press, Inc.

A High Resolution Emission Inventory of Domestic Burning in Rural Region of Northeast China Based on Household Consumption

Domestic burning emits large amounts of pollutants into the ambient air due to incomplete and inefficient combustion, with significant impacts on indoor air quality and human health. Northeast China is one of the major contributors to domestic burning emissions in China;however, the high-resolution emissions inventories of domestic biomass and coal burning in Northeast China are lacked, which are needed to estimate the extent of its impact. In this study, we established a town-level emissions inventory of gaseous pollutants and particulate matter(PM) from domestic biomass and coal burning, based on per household consumption in each town in rural region of Northeast China. The results revealed that biomass burning was the major domestic burning source over the region in 2016. Domestic biomass burning is the major contributor to PM and volatile organic compounds(VOCs) emissions, while coal burning is the major contributor to SO2 emissions. High emissions intensities were concentrated around the cities of Harbin, Suihua, Changchun, Qiqihar, and Chifeng, each with emissions intensity for PM2.5 and VOCs of more than 2000 Mg per 27 km × 27 km grid cell. Additionally, there are three burning peaks(6-7 am, 12 pm and 4-7 pm) during both the heating(from October to April) and non-heating seasons(from May to September), due to cooking and heating. The burning peaks in the non-heating season were more notable than those in the heating season. These results suggest that the government should pay more attention to domestic biomass and coal burning in rural areas, in order to reduce pollutant emissions and control regional haze during the heating season.

Deposition of nanoparticles on school eyeglasses in urban and rural areas:A methodology for a more real assessment of the possible impacts

Because incomplete confirmation is available concerning the influential role of atmosphere contamination on conjunctivitis,myopia,asthma,and allergic rhinitis in Brazil,the focus of the present work is to explore the possible relations among atmosphere contamination and eye problems.Rather that a case study on eye diseases,by way of questionnaires supplemented by the investigation of nanoparticles(NPs)on eyeglasses,the study examines the mechanisms in which NPs and ultra-fine particles are deposited on the glasses of children up to 10 years of age in urban and rural area.The important connection between atmosphere contaminants and individual protection equipment justifies improving indoor school properties in order could protect children’s eyes,particularly in high-pollution/high-particulate areas.

Pollution levels and characteristics of phthalate esters in indoor air in hospitals

The concentrations of phthalate esters（PAEs） in Chinese hospitals were investigated by simultaneously determining concentrations of gas- and particle-phase PAEs. PAEs were detected in two third-class first-grade hospitals, two second-class first-grade hospitals, and a community health service center. Hospital drugstores had the highest concentration（24.19 μg/m3）, which was 1.54 times that of newly decorated houses. The second highest concentration was found in the transfusion rooms, averaging 21.89 μg/m3; this was followed by the concentrations of PAEs in the nurse＇s workstations, the wards, and the doctor＇s offices, with mean concentrations of 20.66, 20.0, and 16.92 μg/m3, respectively. The lowest concentrations were found in the hallways（16.30 μg/m3）. Of the six different kinds of PAEs found, major pollutants included diethyl phthalates, dibutyl phthalates, butylbenzyl phthalates and di（2-ethylhexyl） phthalates, comprising more than 80% of all PAEs present.Meanwhile, a comparison between different wards showed that PAE concentrations in the maternity wards were 1.63 times higher than in the main wards. Based on known health hazards, our results suggest that the PAEs seriously influence the health of the pregnant women and babies; therefore, it is of great importance to take the phthalate concentrations in hospitals into consideration. In addition, hospital indoor air was more seriously contaminated than the air of newly decorated houses.

Vertically-resolved indoor measurements of air pollution during Chinese cooking

Chinese cooking features several unique processes,e.g.,stir-frying and pan-frying,which represent important sources of household air pollution.However,factors affecting household air pollution and the vertical variations of indoor pollutants during Chinese cooking are less clear.Here,using low-cost sensors with high time resolutions,we measured concentrations of five gas species and particulate matter(PM)in three different sizes at multiple heights in a kitchen during eighteen different Chinese cooking events.We found indoor gas species were elevated by 21%-106%during cooking,compared to the background,and PMs were elevated by 44%-159%.Vertically,the pollutants concentrations were highly variable during cooking periods.Gas species generally showed a monotonic increase with height,while PMs changed more diversely depending on the cooking activity's intensity.Intense cooking,e.g.,stir-frying,pan-frying,or cooking on high heat,tended to shoot PMs to the upper layers,while moderate ones left PMs within the breathing zone.Individuals with different heights would be subject to different levels of household air pollution exposure during cooking.The high vertical variability challenges the current indoor standard that presumes a uniform pollution level within the breathing zone and thus has important implications for public health and policy making.

Study on Testing the Composition of Indoor Air Pollution to Benzene Series by Laser Mass Spectrometry

This paper reports some experimental detecting results of pollutants in the atmosphere by means of laser mass spectrometry. For toluene as calibration gas, the calibration procedure was also given. Benzene, toluene and xylene were discovered in testing indoor atmosphere resulting from dope in the course of fitment. Meanwhile, it is noticeable that the concentration of various harmful elements is obviously decreasing as timegoeson.

Numerical simulation of formaldehyde distribution characteristics in the high-speed train cabin

The global concern over indoor air pollution in public vehicles has grown significantly.With a focus on enhancing passengers’comfort and health,this study endeavors to investigate the distribution characteristics of formaldehyde within a high-speed train cabin by employing a computational fluid dynamics(CFD)model which is experimentally validated in a real cabin scenario.The research focuses on analyzing the impact of air supply modes,temperature,relative humidity,and fresh air change rate on the distribution and concentration of formaldehyde.The results demonstrate that the difference in average formaldehyde concentration between the two air supply modes is below 1.3%,but the top air supply mode leads to a higher accumulation of formaldehyde near the sidewalls,while the bottom air supply mode promotes a more uniform distribution of formaldehyde.Furthermore,the temperature,relative humidity,and fresh air change rate are the primary factors affecting formaldehyde concentration levels,but they have modest effects on formaldehyde’s distribution pattern within the cabin.As the temperature and relative humidity increase,the changes in formaldehyde concentrations in response to variations in these factors become more evident.Importantly,the formaldehyde concentration may surpass the standard limit of 0.10 mg/m^(3)if the fresh air change rate falls below 212 m^(3)/h.This research provides a systematic approach and referenceable results for exploring formaldehyde pollution in high-speed train cabins.

Reconsidering gas as clean energy:Switching to electricity for household cooking to reduce NO_(2)-attributed disease burden

Nitrogen dioxide(NO_(2))is a prevalent air pollutant in urban areas,originating from outdoor sources,household gas consumption,and secondhand smoke.The limited evaluation of the disease burden attributable to NO_(2),encompassing different health effects and contributions from various sources,impedes our understanding from a public health perspective.Based on modeled NO2 exposure concentrations,their exposure–response relationships with lung cancer,chronic obstructive pulmonary disease,and diabetes mellitus,and baseline disability-adjusted life years(DALYs),we estimated that 1,675(655–2,624)thousand DALYs were attributable to NO2 in urban China in 2019[138(54–216)billion Chinese yuan(CNY)economic losses].The transition from gas to electricity for household cooking was estimated to reduce the attributable economic losses by 35%.This reduction falls within the range of reductions achieved when outdoor air meets the World Health Organization interim target 3 and air quality guidelines for annual NO_(2),highlighting the significance of raising awareness of gas as a polluting household energy for cooking.These findings align with global sustainable development initiatives,providing a sustainable solution to promote public health while potentially mitigating climate change.

Fast prediction for multi-parameters(concentration,temperature and humidity)of indoor environment towards the online control of HVAC system

Heating,ventilation and air conditioning(HVAC)systems are the most energy-consuming building implements for the improvement of indoor environmental quality(IEQ).We have developed the optimal control strategies for HVAC system to respectively achieve the optimal selections of ventilation rate and supplied air temperature with consideration of energy conservation,through the fast prediction methods by using low-dimensional linear ventilation model(LLVM)based artificial neural network(ANN)and low-dimensional linear temperature model(LLTM)based contribution ratio of indoor climate(CRI_((T))).To be continued for integrated control of multi-parameters,we further developed the fast prediction model for indoor humidity by using low-dimensional linear humidity model(LLHM)and contribution ratio of indoor humidity(CRI_((H))),and thermal sensation index(TS)for assessment.CFD was used to construct the prediction database for CO_(2),temperature and humidity.Low-dimensional linear models(LLM),including LLVM,LLTM and LLHM,were adopted to expand database for the sake of data storage reduction.Then,coupling with ANN,CRI_((T)) and CRI_((H)), the distributions of indoor CO_(2) concentration,temperature,and humidity were rapidly predicted on the basis of LLVM-based ANN,LLTM-based CRIm and LLHM-based CRM respectively.Finally,according to the self-defined indices(i.e.,E_(V),E_(T),E_(H)),the optimal balancing between IEQ(indicated by CO_(2) concentration,PMV and TS)and energy consumption(indicated by ventilation rate,supplied air temperature and humidity)were synthetically evaluated.The total HVAC energy consumption could be reduced by 35%on the strength of current control strategies.This work can further contribute to development of the intelligent online control for HVAC systems.

Removal of formaldehyde over Mn_xCe_(1- x)O_2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of Ce O2 to form a solid solution. The catalytic activity was best at x = 0.5, at which the temperature of 100% removal rate is the lowest（270°C）. The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5 wt.% Cu Oxinto Mn0.5Ce0.5O2. With ozone catalytic oxidation, HCHO（61 ppm） in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV（gas hourly space velocity） of 10,000 hr-1at 25°C. The effect of the molar ratio of O3 to HCHO was also investigated. As O3/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O3/HCHO ratio of 8, the mineralization efficiency of HCHO to CO2 was 86.1%. At 25°C, the p-type oxide semiconductor（Mn0.5Ce0.5O2） exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as Ti O2, which had a low ozone decomposition efficiency（9.81%）. At a GHSV of 10,000 hr-1, [O3]/[HCHO] = 3 and temperature of 25°C, a high HCHO removal efficiency（≥ 81.2%） was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.

Photocatalytic oxidation of gaseous benzene,toluene and xylene under UV and visible irradiation over Mn-doped TiO_(2)nanoparticles

The photocatalytic oxidation of gaseous benzene,toluene and xylene(BTX)over un-doped,0.1 and 1 wt%Mn-TiO_(2)nanoparticles under ultraviolet and visible irradiation was studied in atmosphere of synthetic air or inert gas.The photocatalytic decomposition efficiency and the oxidation products were determined using a Static Photochemical Reactor coupled with FTIR spectroscopy.BTX underwent efficient decomposition over Mn-TiO_(2)photocatalysts under UV irradiation,more with oxygen presence and less without oxygen.More important toluene and xylene went substantial decomposition over 0.1 mol%Mn-TiO_(2)under visible irradiation with oxygen presence.The main final oxidation products in the UV photocatalysis of BTX were CO_(2),CO and H2O,with CO_(2) and CO yields 4 and 2 respectively.The conversion percentage of benzene,toluene,and xylene to CO_(2) were 63.6%,56.4%,51.8%,and to CO 29%,26.5%,23.2%,respectively.In the visible photocatalysis of toluene and xylene the yields of CO were insignificant.Formation of carbon containing deposits on TiO_(2)surfaces was observed after extensive UV photocatalysis of toluene and xylene,and such by-products surface coverage may reduce the photocatalytic activity of TiO_(2)samples.Some aspects of the photocatalytic mechanism were examined.

Photocatalytic removal of NO and NO_2 using titania nanotubes synthesized by hydrothermal method

In this study, the photocatalysts of titania nanotubes （TNTs） were synthesized at different calcination temperatures using commercial Degussa TiO2 （P25） as a precursor. The materials were then characterized by BET, SEM, TEM, and XRD analyses. The photocatalytic reactions with NO and NO2 under UV-A irradiation were both performed. The results showed that the photocatalytic reaction rate of NO was much faster than that of NO2, and the conversion of NO2 to nitrate was the rate-limiting step for photocatalytic removal of NOx if the nitrate produced cannot be removed continuously from the photocatalyst surface. For TNTs calcined at different temperatures, a significant enhancement was observed on the total NOx removal efficiency by TNT calcined at 500℃ for both NO and NO2 photocatalytic reaction, which could be attributed to its high anatase crystallinity as well as high surface area. These two factors affect primarily on the NO2 conversion step in which the high anatase crystallinity could be responsible for the high efficiency at the beginning, while the high surface area could be accounted for retaining this high efficiency from nitric acid poisoning during the test period.

Effects of biomass pellet composition on the thermal and emissions performances of a TLUD cooking stove

Indoor air pollution is ranked the 5th in the Global Burden of Disease index of the World Health Organization(WHO).Almost half of the world’s population depends on biomass fuels to meet their basic energy requirements for cooking,lighting and space heating.When fuel is badly combusted in poorly designed stoves,the fuel-stove combination results in high level of noxious emissions entering the home,accumulating to dangerous levels.In this study,a Chinese unvented top lit updraft(TLUD)biomass stove was operated with three different biomass pellets formed from corn stover,cotton stalk and peanut shells.The performance tests were conducted according to the latest standard from the Chinese Ministry of Agriculture.The calorific value,moisture level,volatile matter and elemental composition are reported for each.The thermal efficiencies of the stove were 15.3%,10.1%and 14.4%,respectively.The cooking powers were 2.68 kW,1.61 kW and 1.57 kW.The exhaust was collected using a hood and tunnel.The CO,NO and NOX were drawn after passing 1.5 m along the tunnel and the Particulate Matter(PM)was sampled after 1.6 m.The Emission Factors(EF)for CO,NO,NOX and PM_(10) are reported on both a mass per unit energy delivered to the pot(g/MJ_(NET))and a mass per mass of fuel basis(g/kg).The range for CO was 4.56-7.61 g/MJ_(NET)(11.25-21.25 g/kg);NO was 0.75-1.23 g/MJ_(NET)(2.09-3.04 g/kg);NO_(x) was 1.13-1.90 g/MJ_(NET)(3.14-4.86 g/kg);PM_(10) was 0.59-0.85 g/MJ_(NET)(1.67-2.09 g/kg).The range in these values was more significantly influenced by the fuel moisture content and the percentage of volatile matter than by variations in the elemental composition.