Estimating elemental composition of personal PM2.5 by a modeling approach in two megacities, China.

Personal exposure to PM2.5, and the elemental composition therein, may vary greatly from ambient measurements at fixed monitoring sites. Here, we characterized the differences between personal, indoor, and outdoor concentrations of PM2.5-bound elements, and predicted personal exposures to 21 PM2.5-bound elements. Personal-indoor-outdoor PM2.5 filter samples were collected for five consecutive days across two seasons from 66 healthy non-smoking retired adults in Beijing (BJ) and Nanjing (NJ), China. Personal element-specific models were developed using liner mixed effects models and evaluated by R2 and root mean square error (RMSE). The mean (SD) concentrations of personal exposures varied by element and city, ranging from 2.5 (1.4) ng/m3 for Ni in BJ to 4271.2 (1614.8) ng/m3 for S in NJ. Personal exposures to PM2.5 and most elements were significantly correlated with both indoor and outdoor (except Ni in BJ) measurements, but frequently exceeded indoor levels and fell below outdoor levels. Indoor and outdoor PM2.5 elemental concentrations were the strongest determinants of most personal elemental exposures, with RM2 ranging from 0.074 to 0.975 for indoor and from 0.078 to 0.917 for outdoor levels, respectively. Home ventilation conditions (especially window opening behavior), time-activity patterns, meteorological factors, household characteristics, and season were also key factors influencing personal exposure levels. The final models accounted for 24.2 %-94.0 % (RMSE: 0.135-0.718) of the variance in personal PM2.5 elemental exposures. By incorporating these crucial determinants, the modeling approach used here can improve PM2.5-bound elemental exposure estimates and better associate compositionally dependent PM2.5 exposures and health risks.

Neglected Aspects of SARS-CoV-2 Aerosol Transmission in Bathrooms of Multistory and High-Rise Buildings - Beijing Municipality, China, October 2022.

What is already known about this topic?: There is a toilet flush-soil stack-floor drain pathway of aerosol transmission in multistory and high-rise buildings, but the influencing factors are not completely clear. What is added by this report?: The poor airtightness of the connecting parts of the floor drain, as well as pressure fluctuations in the sewage pipe during toilet flushing caused by blockage of the soil stack vent, may lead to the cross-floor transmission of viral aerosols through the soil stack and floor drains. What are the implications for public health practice?: In multistory and high-rise buildings, the bathroom floor drains should be kept sealed, and floor drain connecting parts should be airtight. Furthermore, the soil stack vent should not be blocked. In this way, the cross-floor transmission of viral aerosols can be effectively reduced.

Personal exposure to PM2.5 in different microenvironments and activities for retired adults in two megacities, China.

Microenvironmental concentrations and time-activity patterns influence personal exposure to fine particulate matter (PM2.5). However, the variations and contributions of PM2.5 exposures from various microenvironments (MEs) and activities remain unclear. In this study, gravimetrically corrected real-time personal PM2.5 measurements were collected during routine activities in different MEs from 66 non-smoking retired adults. Exposure data were collected for five consecutive days over two seasons in Nanjing (NJ) and Beijing (BJ), China. Measured PM2.5 concentrations varied substantially both between and within different MEs and activities. The highest average concentrations were observed in restaurants (NJ: mean 192 µg/m3, SD 242 µg/m3; BJ: mean 91 µg/m3, SD 79 µg/m3) and were associated with sources such as passive smoking and cooking emissions. Overall, PM2.5 concentrations in different MEs and activities were moderately to highly correlated with outdoor PM2.5 concentrations (Spearman's r = 0.51-0.97) except in restaurants and during passive smoking. The at-home ME contributed approximately 85 % of the total PM2.5 exposure, corresponding to the participants spending about 87 % of their time there. The majority of household exposures occurred during sleeping, cooking, and other home-based activities. Transportation accounted for <5 % of total exposure. Our results indicate that improving indoor air quality, especially residential indoors, is important to reduce personal exposure to PM2.5.

Early Dysbiosis and Dampened Gut Microbe Oscillation Precede Motor Dysfunction and Neuropathology in Animal Models of Parkinson's Disease.

BACKGROUND: Studies have shown different gut microbiomes in patients with Parkinson's disease (PD) compared to unaffected controls. However, when the gut microbiota shift toward dysbiosis in the PD process remains unclear. OBJECTIVE: We aim to investigate the changes in gut microbiota, locomotor function, and neuropathology longitudinally in PD rodent models. METHODS: Fecal microbiota were longitudinally assessed by sequencing the V4-V5 region of the 16S ribosomal RNA gene in a human mutant α-synuclein over-expressing mouse model of PD, SNCA p.A53T mice, and the non-transgenic littermate controls. The locomotor function, neuronal integrity, and α-synuclein expression in the different brain regions were compared between groups. Human fecal microbiota communities from 58 patients with PD and 46 unaffected controls were also analyzed using metagenomic sequencing for comparison. RESULTS: Compared to non-transgenic littermate controls, the altered gut microbiota of the SNCA p.A53T mice can be detected as early as 2 months old, and the diurnal oscillation of the gut microbiome was dampened throughout PD progression starting from 4 months old. However, neuropathology changes and motor deficits were observed starting at 6 months old. Similar changes in altered gut microbiota were also observed in another PD genetic mouse model carrying the LRRK2 p.G2019S mutation at 2 months old. Among the commonly enriched gut microbiota in both PD genetic mouse models, the abundance of Parabateroides Merdae and Ruminococcus torques were also increased in human PD patients compared to controls. CONCLUSION: These findings revealed the altered gut microbiota communities and oscillations preceding the occurrence of neuropathy and motor dysfunction in the PD process.

Air Pollution Health Impact Monitoring and Health Risk Assessment Technology and Its Application - China, 2006-2019.

Air pollution is a significant risk factor contributing to the burden of disease in China. Health risk assessment and management are important to reduce the impact of air pollution on public health. To help formulate standardized health risk assessment techniques, a series of studies were conducted from 2006 to 2019. Through systematic review, study of molecular mechanisms, epidemiological investigation, and health effect monitoring, the overall project established a monitoring and evaluation indicator system, a comprehensive information platform, software for automatic data cleaning, and standardized health risk assessment techniques. Technical specifications have been issued by the National Health Commission for promoting health risk assessments across China. This paper introduces the project, the research approach, its main research accomplishments, innovations, and public health significance, and describes directions for further research.

Cardiovascular benefits of air purifier in patients with stable coronary artery disease: A randomized single-blind crossover study.

Background: Exposure to PM2.5 will accelerate the progression of cardiovascular diseases. Air purifier can reduce the PM2.5 exposure and theoretically alleviate the influence of PM2.5 on patients with stable coronary artery disease (SCAD). However, few studies of the protective effect showed significant results because the interferent effects of routine medication had not been taken into account. In order to explore the actual effect on patients with SCAD, we conducted a randomized single-blind crossover air purifier intervention trial. Method: Levels of PM2.5 exposure during intervention and cardiovascular indicators (inflammation, coagulation, plaque stability, and blood lipids) after intervention were detected, meanwhile the information of drug use was obtained by questionnaire. The kinds of drug used by more than 20% of the subjects were sorted out. And the influence of these drugs on cardiovascular indicators was summarized through literature review. Based on that, the drug use was included as a variable in linear mixed effects models that used to analyze the associations between PM2.5 exposure reduction by air purifier and cardiovascular indicators. Results: The result revealed that the interpretation contribution rate of drug use was more than that of PM2.5 exposure. The level of C-reactive protein significantly decreased by 20.93% (95%CI: 6.56%, 33.10%), 23.44% (95%CI: 2.77%, 39.39%) and 24.11% (95%CI: 4.21%, 39.69%) on lag1, lag01 and lag02 respectively, while the level of high-density lipoprotein cholesterol significantly increased by 5.10% (95%CI: 0.69%, 9.05%), 3.71% (95%CI: 0.92%, 6.60%) and 6.48% (95%CI: 2.58%, 10.24%) respectively on lag0, lag1 and lag01 associated with an interquartile range decrease of 22.51 µg/m3 in PM2.5 exposure. Conclusion: The study shows positive effects of air purifier on SCAD, and also provides methodological reference for future related research.

[Risk assessment of excess mortality attribute to PM_(2.5) exposure in 5 cities in China in 2018].

OBJECTIVE: To assess the risk of excess mortality caused by exposure to PM_(2.5) in 5 cities in China. METHODS: Surveillance data on daily concentration of PM_(2.5), meteorology and death-causes were collected from 2015 to 2018 in Harbin, Xi& apos; an, Nanjing, Chengdu and Guangzhou cities. Generalized additive model(GAM) was used to analyze acute exposure-response coefficients of PM_(2.5) exposure on the mortality. Using daily 24-hour average concentration of PM_(2.5) in 2018 to estimate the exposure levels of the population, with PM_(2.5) 24-hour average concentration limit of the ambient air quality standard(GB 3095-2012) for reference concentration(75 µg/m~3), and applicating the health risk assessment model, the excess deaths attribute to PM_(2.5) exposure in the 5 cities in 2018 was estimated. RESULTS: Attribute to PM_(2.5) exposure, the excess cases of death caused by circulatory system diseases in Harbin and Guangzhou were 35 and 92, the excess cases caused by respiratory diseases in Xi& apos; an was 70, the excess cases of caused by non-accident in Nanjing was 69, and the excess cases caused by non-accidental, respiratory and circulatory diseases in Chengdu were 588, 210 and 134 in 2018. CONCLUSION: PM_(2.5) exposure could increase the excess mortality risk, which varies among different cities.

Risk factors and on-site simulation of environmental transmission of SARS-CoV-2 in the largest wholesale market of Beijing, China.

From June 11, 2020, a surge in new cases of coronavirus disease 2019 (COVID-19) in the largest wholesale market of Beijing, the Xinfadi Market, leading to a second wave of COVID-19 in Beijing, China. Understanding the transmission modes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the personal behaviors and environmental factors contributing to viral transmission is of utmost important to curb COVID-19 rise. However, currently these are largely unknown in food markets. To this end, we completed field investigations and on-site simulations in areas with relatively high infection rates of COVID-19 at Xinfadi Market. We found that if goods were tainted or personnel in market was infected, normal transaction behaviors between sellers and customers, daily physiological activities, and marketing activities could lead to viral contamination and spread to the surroundings via fomite, droplet or aerosol routes. Environmental factors such as low temperature and high humidity, poor ventilation, and insufficient hygiene facilities and disinfection practices may contribute to viral transmission in Xinfadi Market. In addition, precautionary control strategies were also proposed to effectively reduce the clustering cases of COVID-19 in large-scale wholesale markets.

Visible-Light-Promoted Synthesis of α-CF2H-Substituted Ketones by Radical Difluoromethylation of Enol Acetates.

An efficient and novel visible-light-promoted radical difluoromethylation of enol acetates for the synthesis of α-CF2H-substituted ketones has been described. Upon irradiation under blue LED with catalytic amounts of fac-Ir(ppy)3, this photocatalytic procedure employs difluoromethyltriphenylphosphonium bromide as a radical precursor. Various α-CF2H-substituted ketones are successfully created via designed systems based on the SET process. The methodology has also provided an operationally simple process with broad functional group compatibility.

Determinants of personal exposure to fine particulate matter in the retired adults - Results of a panel study in two megacities, China.

This study aimed to investigate the relationship between outdoor, indoor, and personal PM2.5 exposure in the retired adults and explore the effects of potential determinants in two Chinese megacities. A longitudinal panel study was conducted in Nanjing (NJ) and Beijing (BJ), China, and thirty-three retired non-smoking adults aged 43-86 years were recruited in each city. Repeated measurements of outdoor-indoor-personal PM2.5 concentrations were measured for five consecutive 24-h periods during both heating and non-heating seasons using real-time and gravimetric methods. Time-activity and household characteristics were recorded. Mixed-effects models were applied to analyze the determinants of personal PM2.5 exposure. In total, 558 complete sets of collocated 24-h outdoor-indoor-personal PM2.5 concentrations were collected. The median 24-h personal PM2.5 exposure concentrations ranged from 43 to 79 µg/m3 across cities and seasons, which were significantly greater than their corresponding indoor levels (ranging from 36 to 68 µg/m3, p < 0.001), but significantly lower than outdoor levels (ranging from 43 to 95 µg/m3, p < 0.001). Indoor and outdoor PM2.5 concentrations were the strongest determinants of personal exposures in both cities and seasons, with RM2 ranging from 0.814 to 0.915 for indoor and from 0.698 to 0.844 for outdoor PM2.5 concentrations, respectively. The personal-outdoor regression slopes varied widely among seasons, with a pronounced effect in BJ (NHS: 0.618 ± 0.042; HS: 0.834 ± 0.023). Ventilation status, indoor PM2.5 sources, personal characteristics, and meteorological factors, were also found to influence personal exposure levels. The city and season-specific models developed here are able to account for 89%-93% of the variance in personal PM2.5 exposure. A LOOCV analysis showed an R2 (RMSE) of 0.80-0.90 (0.21-0.36), while a 10-fold CV analysis demonstrated a R2 (RMSE) of 0.83-0.90 (0.20-0.35). By incorporating potentially significant determinants of personal exposure, this modeling approach can improve the accuracy of personal PM2.5 exposure assessment in epidemiologic studies.

The impact of heating season factors on eight PM2.5-bound polycyclic aromatic hydrocarbon (PAH) concentrations and cancer risk in Beijing.

In 2015, 443 atmospheric PM2.5 samples were collected at five sampling sites in Beijing. The concentrations of PM2.5-bound PAH8 (Chr, BaA, BbF, BkF, B[a]P, DBA, BghiP, and IND) were determined via high performance liquid chromatography (HPLC). The annual concentration of PM2.5-bound PAH8, lifetime cancer risk, and the increasing value due to heating season factors (heating and meteorological conditions) were analyzed. The results showed that the sum concentration of PM2.5-bound PAH8 during heating season was 72.6 ng/m3 and higher than the non-heating season concentration of 4.77 ng/m3. The annual concentration was 10.6 ng/m3, which increased 5.83 ng/m3 due to heating season factors. The B[a]P annual concentration was 1.67 ng/m3 and higher than the limit of 1 ng/m3, which was 15.2 times that of non-heating season. Diesel vehicles and gasoline vehicles were the primary PAH8 sources during non-heating season, while the mixed sources of diesel vehicles, gasoline vehicles, and combustion were the dominant PAH8 sources during heating season. The most significant health hazard pollutant was B[a]P, which accounted for 72%, 74%, and 69% of the B[a]P equivalent concentration (B[a]Peq) of PAH8 during heating season, non-heating season, and throughout 2015, respectively. The lifetime cancer risk was 2.67 × 10-6, which increased 1.36 × 10-6 due to heating season factors. Therefore, heating season factors nearly doubled the annual concentration of PM2.5-bound ∑PAH8 and lifetime cancer risk. The results indicated that to protect human health, it is very important to control PM2.5-bound ∑PAH8 emissions during heating season, especially B[a]P emissions.

Pollution characteristics of ambient PM2.5-bound benzo[a]pyrene and its cancer risks in Beijing.

The purpose of this study was to reveal the pollution characteristics of ambient PM2.5-bound benzo[a]pyrene (B[a]P) in Beijing and to assess the lifetime cancer risk from respiratory pathway exposure. The average daily dose was evaluated by the annual concentrations of ambient PM2.5-bound B[a]P, combined with Chinese human exposure factors and the age sensitivity factors. The 70-year lifetime cancer risks of different groups were assessed by the exposure assessment and stochastic analysis method recommended by California Environmental Protection Agency. The groups were divided by age and gender. The results showed that the ambient PM2.5-bound B[a]P concentration during the cold season was 15.7 times greater than that during the warm season in Beijing. The annual average concentrations of PM2.5-bound B[a]P in outdoors and indoors were 1.67 ng/m3 and 1.04 ng/m3, respectively, which exceeded the limit of Chinese National Ambient Air Quality Standard. The cancer risks of PM2.5-bound B[a]P in males, females, and the general population were 9.085 × 10-6, 8.050 × 10-6, and 8.740 × 10-6, respectively. The cancer risk constituent ratios of ambient PM2.5-bound B[a]P in early life (≤16 years of age) for males, females, and the general population were 70.9%, 71.4%, and 71.3%, respectively. The males' cancer risk of PM2.5-bound B[a]P in Beijing was higher than that of the females. The early life cancer risk exposure to PM2.5-bound B[a]P should be paid more attention.

Detection and comparison of microRNAs in the caprine mammary gland tissues of colostrum and common milk stages.

BACKGROUND: MicroRNAs (miRNAs) have a great influence on various physiological functions. A lot of high-throughput sequencing (HTS) research on miRNAs has been executed in the caprine mammary gland at different lactation periods (common milk lactation and dry period), but little is known about differentially expressed miRNAs in the caprine mammary gland of colostrum and peak lactation periods. RESULT: This study identified 131 differentially expressed miRNAs (P < 0.05 and log2 colostrum normalized expression (NE)/peak lactation NE > 1 or log2 colostrum NE/peak lactation NE < -1), including 57 known miRNAs and 74 potential novel miRNAs in the colostrum and peak lactation libraries. In addition, compared with differentially expressed miRNAs in the peak lactation period, 45 miRNAs in the colostrum lactation period were remarkably upregulated, whereas 86 miRNAs were markedly downregulated (P < 0.05 and log2 colostrum NE/peak lactation NE > 1 or log2 colostrum NE/peak lactation NE < -1). The expressions of 10 randomly selected miRNAs was analyzed through stem-loop real-time quantitative PCR (RT-qPCR). Their expression patterns were the same with Solexa sequencing results. Pathway analysis suggested that oestrogen, endocrine, adipocytokine, oxytocin and MAPK signalling pathways act on the development of mammary gland and milk secretion importantly. In addition, the miRNA-target-network showed that the bta-miR-574 could influence the development of mammary gland and lactation by leptin receptor (LEPR), which was in the adipocytokine signalling pathway. Chr5_3880_mature regulated mammary gland development and lactation through Serine/threonine-protein phosphatase (PPP1CA), which was in the oxytocin signalling pathway. CONCLUSIONS: Our finding suggested that the profiles of miRNAs were related to the physiological functions of mammary gland in the colostrum and peak lactation periods. The biological features of these miRNAs may help to clarify the molecular mechanisms of lactation and the development of caprine mammary gland.

[Method for continuous measurement of personal exposure to fine particulate matter].

OBJECTIVE: To develop a new accurate method for continuous measurement of personal exposure to fine particulate matter( PM_(2. 5) ) by integrating the advantage of both light scattering and gravimetric method. METHODS: The PM_(2. 5) concentrations were measured by both light scattering and gravimetric method simultaneously. The ratio of time-weighted average concentrations from gravimetric method to the responding values from light scattering method was calculated as coefficient of correction and used to calibrate the real-time PM_(2. 5) concentrations from light scattering method. RESULTS: The limit of detections( LOD) for 3, 10, 30 and 60 min time-weighted average concentrations of PM_(2. 5) were 4. 6, 4. 0, 3. 9 and 3. 7 µg/m~3, respectively. The precision( relativestandard deviation, RSD) was from 2. 1% to 9. 5%. The 30 min time-weighted average concentrations from this method were highly related to the results from TEOM method which was considered as reference method( Pearson r = 0. 934, P < 0. 001, n = 233), and no significantly bias between these two methods was detected by paired t test( P =0. 957). Zero drift was detected for 3 out of 10 devices with drift values in the range of- 5-- 3 µg/m~3 in the experiment of continuous 24 h monitoring conducted in the lab. And zero shift was also investigated in 7. 5%( 31 /412) field monitoring events, but most of the values shifted were within the range of- 3- 3 µg/m~3. The direction and scale of zero shift were not influenced by PM_(2. 5) concentrations. CONCLUSION: The developed method in this study that combines the advantages of both light-scattering and gravimetric method is validated to measure real-time concentrations of personal exposure to PM_(2. 5) .

Investigation and modeling of the residential infiltration of fine particulate matter in Beijing, China.

The objective of this study was to estimate the residential infiltration factor (Finf) of fine particulate matter (PM2.5) and to develop models to predict PM2.5 Finf in Beijing. Eighty-eight paired indoor-outdoor PM2.5 samples were collected by Teflon filters for seven consecutive days during both non-heating and heating seasons (from a total of 55 families between August, 2013 and February, 2014). The mass concentrations of PM2.5 were measured by gravimetric method, and elemental concentrations of sulfur in filter deposits were determined by energy-dispersive x-ray fluorescence (ED-XRF) spectrometry. PM2.5 Finf was estimated as the indoor/outdoor sulfur ratio. Multiple linear regression was used to construct Finf predicting models. The residential PM2.5 Finf in non-heating season (0.70 ± 0.21, median = 0.78, n = 43) was significantly greater than in heating season (0.54 ± 0.18, median = 0.52, n = 45, p < 0.001). Outdoor temperature, window width, frequency of window opening, and air conditioner use were the most important predictors during non-heating season, which could explain 57% variations across residences, while the outdoor temperature was the only predictor identified in heating season, which could explain 18% variations across residences. The substantial variations of PM2.5 Finf between seasons and among residences found in this study highlight the importance of incorporating Finf into exposure assessment in epidemiological studies of air pollution and human health in Beijing. The Finf predicting models developed in this study hold promise for incorporating PM2.5 Finf into large epidemiology studies, thereby reducing exposure misclassification. IMPLICATIONS: Failure to consider the differences between indoor and outdoor PM2.5 may contribute to exposure misclassification in epidemiological studies estimating exposure from a central site measurement. This study was conducted in Beijing to investigate residential PM2.5 infiltration factor and to develop a localized predictive model in both nonheating and heating seasons. High variations of PM2.5 infiltration factor between the two seasons and across homes within each season were found, highlighting the importance of including infiltration factor in the assessment of exposure to PM2.5 of outdoor origin in epidemiological studies. Localized predictive models for PM2.5 infiltration factor were also developed.

[Study on the influence factors of exhaled breath condensate pH detection of asthma children].

OBJECTIVE: To explore influence factors of exhaled breath condensate (EBC) pH detection and establish standard method for EBC pH detection of asthma children. METHODS: EBC samples were collected using Rtube EBC collection system, and pH values were detected by microelectrode method. RESULTS: The temperatures of sampling condenser tube (from - 18 to 4 degrees C) and duration of collection (from 10 to 30 minutes) has no significant effect on EBC pH of asthma children. After degasification with argon for 4 minutes, the EBC pH became stable. The day to day precisions (relative standard deviation) were 0.74% -1.01%, and the relative deviations between theoretical values and detection values were 0.11% - 0.75% in determining different level of pH standard solutions. The EBC samples for pH detection could be store at - 20 degrees C for 6 months. CONCLUSION: The established method by standardizing influence factors is accurate and convenient. It can be used in the detection of EBC pH of asthma children.

Optically rewritable patterns of nuclear magnetization in gallium arsenide.

The control of nuclear spin polarization is important to the design of materials and algorithms for spin-based quantum computing and spintronics. Towards that end, it would be convenient to control the sign and magnitude of nuclear polarization as a function of position within the host lattice. Here we show that, by exploiting different mechanisms for electron-nuclear interaction in the optical pumping process, we are able to control and image the sign of the nuclear polarization as a function of distance from an irradiated GaAs surface. This control is achieved using a crafted combination of light helicity, intensity and wavelength, and is further tuned via use of NMR pulse sequences. These results demonstrate all-optical creation of micron scale, rewritable patterns of positive and negative nuclear polarization in a bulk semiconductor without the need for ferromagnets, lithographic patterning techniques, or quantum-confined structures.

[Simultaneous determination of 31 volatile organic compounds in decorated rooms by two-stage thermal desorption-capillary gas chromatography].

OBJECTIVE: To establish the monitoring method to simultaneously measure 31 volatile organic compounds in decorated rooms using two-stage thermal desorption-capillary gas chromatography. METHODS: Using the Tenax TA absorption tube to sample, and subsequently desorbed and analyzed by two-stage thermal desorption capillary gas chromatography column, and measured by FID detector. RESULTS: 31 volatile organic compounds can be well separated in the chromatography column. In the experiment, the relative standard deviations of the reoccuring of each compound were within 10%. All the correlation coefficients of linear regression equation were greater than 0.99. The lowest detection limit can reach the concentration level of 1 ng/microl, and the recoveries were 83.2% - 106%. CONCLUSION: The method is applicable to determination of 31 volatile organic compounds in the decorated rooms simultaneously.

[Study on the acquiring data time and intervals for measuring performance of air cleaner on formaldehyde].

OBJECTIVE: The measuring time and measuring intervals to evaluate different type of air cleaner performance to remove formaldehyde were provided. METHODS: The natural decay measurement and formaldehyde removal measurement were conducted in 1.5 m3 and 30 m3 test chamber. RESULTS: The natural decay rate was determined by acquiring formaldehyde concentration data at 15 minute intervals for 2.5 hours. The measured decay rate was determined by acquiring formaldehyde concentration data at 5 minute intervals for 1.2 hours. When the wind power of air cleaner is smaller than 30 m3/h or measuring performance of no wind power air clearing product, the 1.5 m3 test chamber can be used. Both the natural decay rate and the measured decay rate are determined by acquiring formaldehyde concentration data at 8 minute intervals for 64 minutes. CONCLUSION: There were different measuring time and measuring intervals to evaluate different type of air cleaner performance to remove formaldehyde.