[Establishment and Application of Foshan Ozone Concentration Forecast Equation].

The formation and changes of ozone (O3), a secondary pollutant in the atmosphere, are complex, and ozone forecasting has become one of the current problems in air pollution prevention and control. In this study, the relationships between the near-surface O3 concentration and meteorological elements (high- and low-level) in Foshan from 2014 to 2017 were analyzed, and the concentration forecasting equation was established, tested, and applied. The results showed that the near-surface O3 changed closely related to high- and low-level meteorological elements. Meteorological elements such as temperature and sunshine hours were significantly positively correlated with O3 concentration, whereas relative humidity, total (low) cloud cover, and wind speed were negatively correlated with O3. Heavy O3 pollution often occurred with meteorological conditions of low wind speed, sunny days and few clouds, low relative humidity, longer sunshine time, and higher temperature. The definitions of high-concentration O3 potential index (HOPI) and wind direction index (WDI) in the Foshan area could better characterize the meteorological conditions of O3 pollution. Considering 13 meteorological elements, such as HOPI and WDI at different heights, the O3 concentration forecasting equation in the Foshan area was established using multi-indicator stacking and multiple stepwise regression methods. Using the 2018 data, it was found that the correlation coefficient R between the simulated values and the measured values reached 0.82, and the forecast equation had a good fitting effect and predictability.

Hygroscopicity of amino acids and their effect on the water uptake of ammonium sulfate in the mixed aerosol particles.

Amino acids are important water-soluble nitrogen-containing compounds in atmospheric aerosols. They can be involved in cloud formation due to their hygroscopicity and have significant influences on the hygroscopicity of inorganic compounds, which have not yet been well characterized. In this work, the hygroscopic properties of three amino acids, including aspartic acid, glutamine, and serine, as well as their mixtures with ammonium sulfate (AS) were investigated using a hygroscopicity tandem differential mobility analyzer (HTDMA) system. The gradual water uptake of aspartic acid, glutamine and serine particles indicates that they exist as liquid phase at low RH. When mixing either aspartic acid or glutamine with AS by mass ratio of 1:3, we observed a clear phase transition but with a lower deliquescence relative humidity (DRH) with respect to that of pure AS. This suggests the crystallization of AS in the presence of each of these two amino acids. However, as the mass fractions of these two amino acids increased in the mixed particles, the deliquescence transition process was not obvious. In contrast, the crystallization of AS was efficiently hampered even at low content (i.e., 25% by mass) of serine in the mixed particles. The Zdanovskii-Stokes-Robinson (ZSR) method in general underestimated the hygroscopic growth of any mixtures at RH below 79% (prior to AS deliquescence), suggesting both amino acid and the partially dissolved AS contributed the overall hygroscopicity at RH in this range. Relatively good agreements were reached between the measurements and model predictions using the Extended Aerosol Inorganic Model (E-AIM) assuming solid state AS in the mixed particles for 1:3 aspartic acid-AS and glutamine-AS systems. However, the model failed to simulate the water uptake behaviors of any other systems. It demonstrates that the interactions between components within the aerosols have a significant effect on the phase state of the mixed particles.

Assessing transfer distances and separation areas of odorous compounds from probability analysis with numerical dispersion modeling.

Odor pollution caused by volatile compounds from waste-treatment facilities is a typical nuisance, and assessing its potential impacts is crucial. Challenges in odor-dispersion simulation and impact assessment are attributed to the occasional and fluctuant emissions of odorous compounds and varying meteorological conditions for dispersion. This study established an approach to assessing the transfer distances and determining the separation areas of odor pollution by combining probability analysis and numerical dispersion simulation. With a waste transfer station as a case, we analyzed odorous compounds from 96 samples and performed 2190 simulation rounds with different meteorological parameters throughout an entire year by using a specialized model (ModOdor). Ethanol, dimethyl disulfide, and dimethyl sulfide were identified as typical odorous compounds in terms of source intensity and detection frequency. The concentration distribution, probability of transfer distances in terms of month and year, and separation area determination from cumulative probability were investigated. Under most studied conditions, the compound concentrations rapidly decreased after being released. From the year-round perspective, an ethanol concentration exceeding 1 µg/m3 was in approximately 80% probability limited in the area with a radius of 200 m. With a cutoff of 95% probability, the closest transfer distances towards all orientations can circle the odor separation area. The compound concentrations in the separation area had a probability higher than 5% throughout the year to exceed the assigned reference concentrations. The approach and demonstration can solve the mutability problem of odor pollution from a probability perspective and thus potentially improve odor pollution control in waste management.

Quantitative effects of atmospheric diffusion on surface aerosol extinction in the Pearl River Delta region.

Aerosol pollution is closely related to meteorological conditions. In order to accurately evaluate the effectiveness of emission reduction policies, it is very important to separate meteorological effects from emissions in long-term PM changes. In this study, we used surface extinction coefficient (SEC) of aerosol particles as an indicator to estimate the long-term trend of PM pollutant conditions, and proposed a parameter surface ventilation index (SVI) to describe the atmospheric diffusion. A novel method was introduced to quantify the effect of atmospheric diffusion and emissions on SEC from an inter-annual scale, and its applicability and limitations was discussed. The results showed that annual mean SEC exhibited an increasing trend with a rate of 15.6 Mm-1∙year-1 from 2000 to 2007 and a decreasing trend with a rate of 14.4 Mm-1∙year-1 from 2008 to 2018. The annual frequency distribution of SVI obeyed a lognormal distribution. The SVI value mainly concentrated between 300 and 3600 m2.s-1, SEC was negatively correlated with SVI in this range. In most cases, SEC variations were mainly dominated by emissions, and SEC variations at clean sites were more influenced by atmospheric diffusion than that at polluted sites. Emissions remained high during 2003-2007, then gradually decreased during 2008-2014 and finally accelerated decrease during 2015-2018, indicating that control policies have effectively mitigated PM pollution since 2008. In generally, this method can provide valuable information for policy makers to evaluate the emission control measures for air pollution mitigation and prevention.

Dispersion simulation of odorous compounds from waste collection vehicles: Mobile point source simulation with ModOdor.

Odour pollution from municipal solid waste is a public nuisance and a threat to the health of residents nearby. Attention and understanding towards odour emissions from waste collection vehicles are insufficient, and dispersion simulation using conventional modelling tools cannot be applied because their special operational characteristics do not conform to either point or linear sources. This study proposes a new dispersion simulation method for mobile point sources with ModOdor, which is a 3D numerical model previously developed by the authors. The 12-month monitoring data show that ethanol, dimethyl disulphide and methylene chloride were identified as typical odorous compounds released from waste collection vehicles. Ethanol dispersion was simulated as a mobile point source for low- and high-speed modes by synchronously changing temporal and spatial grids in high precision. Results revealed the variations in concentration distribution, dispersion distance and impact duration. In general, a diameter of area with odour activity value higher than 0.1 was identified at approximately 30-50 m after stable dispersion. The impact duration varied from approximately 20 s to 40 s along with the tested source intensities, wind directions and speeds with a benchmark of 10 µg·m-3. This study verified the applicability of the proposed method for the dispersion simulation of mobile point sources and provided useful approach and information for evaluating the odour pollution from waste collection vehicles.

[Optical Absorption Properties of Brown Carbon Aerosols in Guangzhou].

In this work, we conducted measurements using a seven-wavelength aethalometer, an online OCEC analyzer, and a MARGA to investigate brown carbon (BrC) absorption properties and source origins during the winter of 2014 at Panyu station, Guangzhou. The results showed that the average absorption contributions of BrC decreased with an increase in wavelength, measured as 25.9%, 19.7%, 14.1%, 11.6%, and 7.7% at 370 nm, 470 nm, 520 nm, 590 nm, and 660 nm, respectively. Diurnal variations in BrC absorption and the concentrations of potassium cations (K+) and organic carbon (OC) was high at night and low during the day, which was attributed to biomass burning. This indicated that BrC was emitted from straw burning in rural areas and accumulated in the steady planetary boundary layer at night. Diurnal variations in the ratio of BrC absorption to OC concentrations showed a distinct dip during the afternoon, indicating that aged aerosol and secondary organic aerosol (SOA) had a weaker BrC absorption capacity. There was a good overall correlation between BrC absorption and K+ concentrations. BrC absorption was also moderately related to the concentrations of ammonium cations (NH4+) and nitrate anions (NO3-).

Statistical correlations on the emissions of volatile odorous compounds from the transfer stage of municipal solid waste.

Odor pollution from treatment facilities and municipal solid waste (MSW) has caused wide public concern. Odorous compounds released from these facilities possess complex composition. Therefore, identifying typical odorous compounds and using their release rates to estimate those of other compounds may simplify the monitoring and evaluation of odor pollution. This study investigates the correlations of the release data of odorous compounds from a statistical perspective. For 12 months, we conducted in site monitoring in an MSW transfer station once each month to obtain 96 emission samples, and over 100 odorous compounds were quantified for each sample. Oxygenated compounds had considerable high release rates throughout the period, and ethanol was the dominant compound. Ethanol, dimethyl disulfide and methyl mercaptan were the top key compounds that contributed to the odor activity value. Correlation analyses within and across the categories showed that only a few compounds in saturated hydrocarbons and aromatic compounds had strong correlations with release rate. The coefficient of correlation between ethylbenzene and 19 other compounds, which covered only 25% of all the identified compounds in this study, was >0.5. These results show that representative compounds cannot be used in the calculation of release rate during the transfer stage.

[A Method of Aerosol Particle Number Size Distribution Inversed by PM2.5 Mass Concentration in PRD].

The aerosol particle number size distribution(PNSD) is of great importance in calculating atmospheric radiation and optics. It can effectively supplement the inadequate observation of PNSD using the widely known aerosol mass concentration (PM2.5) measurement to invert PNSD. It would be valuable for research that needs PNSD data, like atmospheric visibility calculation. This paper created a PNSD inversed method based on the statistics and parameterization of the dry aerosol PM2.5 and PNSD dataset from the Guangzhou urban site's simultaneous measurements from November 2014 to January 2015. The inversed results appeared good in the accumulation mode, whereas more differences showed with higher PM2.5 loading. The applicability and stability of this method makes it preferable. It would provide advanced technical support for the visibility calculation and application in PRD.

Parameter sensitivity to concentrations and transport distance of odorous compounds from solid waste facilities.

Treatment facilities dealing with municipal solid waste (MSW) are typical pollution sources of urban odor nuisance which threatens public health and environmental safety. Dispersion simulation with specialized models is an important approach for simulating the concentration distribution and estimating the transport distances of the released odorous compounds. Given that the temporal and spatial distribution are affected by many factors with different variations and functions. This study investigated the influence of key parameters on the dispersion of odor compounds on the basis of a numerical atmospheric dispersion model. The sensitivity analysis was applied to quantitatively identify their influence on the concentration distributions and transport distances. The results reveal that source intensity is a sensitive parameter in the whole domain under the specified dispersion conditions, with the sensitivity ratios around 1 to concentrations and of 1.5-2.5 to transport distances. Wind speed possesses higher sensitivity ratios at the upwind direction than the downwind direction. Horizontal diffusion coefficient is sensitive to concentrations only in the area of a typical radius of 500 m from the source. Degradation reaction constant and wet deposition are not sensitive in either concentration distribution or transport distances. The most sensitive parameters present respective importance to the transport distances when different olfactory thresholds of compounds are applied to determine the protection area of odor pollution. This study thus provides important information to the application of dispersion models and the data collection of the most sensitive parameters in odor pollution evaluation and management.

Real time analysis of lead-containing atmospheric particles in Guangzhou during wintertime using single particle aerosol mass spectrometry.

The toxic effects of lead on human health and the environment have long been a focus of research. To explore sources of lead in Guangzhou, China, we investigated atmospheric lead-containing particles (LCPs) during wintertime using a single particle aerosol mass spectrometer (SPAMS). Based on mass spectral features, LCPs were classified into eight major particle types, including Pb-Cl and Pb-Cl-Li (coal combustion and waste incineration), Pb-Cl-EC and Pb-Cl-OC (diesel trucks and coal combustion), Pb-Cl-Fe (iron and steel industry), Pb-Cl-AlSi (dust), Pb-Sec (secondary formation), and Pb-Cl-Zn (industrial process); these sources (in parentheses) were identified by comparing atmospheric LCP mass spectra with authentic Pb emission source mass spectra. Sampling periods with LCP number fractions (NFs) more than three times the average LCP NF (APF = 4.35%) and below the APF were defined as high LCP NF periods (HLFPs: H1, H3, and H5) and low LCP NF APF periods (LLFPs: L2 and L4), respectively. Diurnal patterns and high Pb-Sec content during LLFPs indicate that photochemical activity and heterogeneous reactions may have controlled Pb-Sec particle formation. The inverse Pb-Cl and Pb-Sec particle diurnal trends during LLFPs suggest the replacement of Cl by sulfate and nitrate. On average over the five periods, ~ 76% of the LCPs likely arose from coal combustion and/or waste incineration, which were dominant sources during all five periods, followed by diesel trucks during LLFPs and iron- and steel-related sources during HLFPs; HLFP LCPs arose mainly from primary emissions. These results can be used to more efficiently control Pb emission sources and prevent harm to human and environmental health from Pb toxicity.

Influence of aerosol hygroscopicity and mixing state on aerosol optical properties in the Pearl River Delta region, China.

Both the effects of aerosol hygroscopicity and mixing state on aerosol optical properties were analyzed using ground-based measurements and a Mie model in this study. The sized-resolved particle hygroscopic growth factor at RH = 90% (Gf(90%)) and the enhancement factor for the scattering coefficients (f(RH)sp) were measured by a self-constructed Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) and two nephelometers in parallel (PNEPs) respectively from 22nd February to 18th March 2014 in the Pearl River Delta, China. In addition, the particle number size distribution (PNSD) and BC mass concentration (MBC) were measured simultaneously. During the observation period, the f(RH)sp increased sharply along with increasing RH (40%-85%) and the value of f(80%)sp was 1.77 ±â€¯0.18. The mean Gf(90%) for all particles are 1.44 (80 nm), 1.48 (110 nm), 1.52 (150 nm) and 1.55 (200 nm), and the mean Gf(90%) for more-hygroscopic particles are 1.58 (80 nm), 1.63 (110 nm), 1.66 (150 nm) and 1.67 (200 nm) respectively. Based on Gf, PNSD and MBC, the enhancement factor of the aerosol optical properties (extinction (f(RH)ep), scattering (f(RH)sp), backscattering (f(RH)hbsp), absorption (f(RH)absp), and hemispheric backscatter fraction (f(RH)hbsp)) were calculated under three aerosol mixing state assumptions. The results show that the calculated f(80%)sp values agreed well with the ones measured by PNEPs, illustrating that the Gf size distribution fittings are reasonable. The f(RH)ep, f(RH)sp and f(RH)hbsp increased along with increasing RH for three mixtures, while f(RH)HBF decreased. The f(RH)absp increased for the homogenously internal mixture, but remained stable for the external mixture. For the core-shell mixture, the f(RH)absp increased from RH = 0 to 75% and then decreased, due to a decrease of light entering the BC core. The enhancement factor of aerosol direct radiative forcing (f(RH)Fr) increased sharply as the RH elevated for the external mixing state. However, f(RH)Fr increased or decreased along with the elevated RH for the homogenously internal mixture and the core-shell mixture depending on initial value of the aerosol direct radiative forcing (∆Fr) in a dry condition.

Emission characteristics and variation of volatile odorous compounds in the initial decomposition stage of municipal solid waste.

The odour pollution occurring in the initial decomposition stage of municipal solid waste (MSW), including collection, transfer and transportation, has not been sufficiently emphasised. Thus the emission characteristics of and variation in odorant generation in this stage were investigated through simulation experiments at different temperatures, waste composition and processing durations. Out of 120 odorous compounds, 52 were detected in seven categories under all tested conditions, with significant variations. In the total concentration and emission rate, ethanol generally showed the largest proportion (larger than 80% on average), followed by unsaturated hydrocarbons which were dominated by propylene (13.1% on average of concentration proportion). The total emissions rapidly increased with processing duration when the temperatures were 15°C to 30°C. The proportion of ethanol increased significantly from 40.1% at 6h to 82.9% at 24h at 30°C. By contrast, a low temperature (5°C) resulted in low concentrations, and propylene accounted for the largest proportion instead of ethanol. With increasing temperature, biogenic compounds with large proportions increased more rapidly than xenobiotic compounds because of accelerated biological process and volatilisation. The emission rates of oxygenated compounds, saturated hydrocarbons, unsaturated hydrocarbons and halogenated compounds significantly increased (by approximately 20% to 50%) with an increase in easily biodegradable portion in the MSW. The proportions were relatively stable with the MSW composition variation, suggesting that most xenobiotic compounds were also derived from easily degradable portions. The olfactory evaluation showed that organic sulphur compounds contributed the most (approximately 75% to 95%) to odour pollution at the beginning of the stage because of their extremely low olfactory thresholds, with methanethiol as the dominant contributor (approximately 50% to 80% when detected). Results of this study can provide useful information for an improved understanding and monitoring of odorant emissions in the initial decomposition stage of MSW.

An analysis of aerosol liquid water content and related impact factors in Pearl River Delta.

Aerosol liquid water content (ALWC) has an important effect on atmospheric visibility as well as heterogeneous chemical reactions. In this paper, we used the data size-resolved particle hygroscopic growth factor, and particle number size distribution (PNSD) obtained from H-TDMA and SMPS to compute ALWC at the Guangzhou Panyu site from the winter of 2014 and the spring of 2015. The corresponding results were relatively consistent with the trend for ALWCISO calculated from the ISORROPIA II thermodynamic equilibrium model based on the measurement of aerosol water-soluble ionic compositions obtained from MARGA, with a linear fit yielding an R2 value of 0.76. The fact that ALWCHTDMA was somewhat higher than ALWCISO at low RH values was at least partially attributable to the fact that effects resulting from organic matter hygroscopicity were not taken into account when computing ALWCISO. In sensitivity testing, ambient relative humidity, PNSD and particle hygroscopicity were all found to affect ALWC, in that order. Particles of different modes made different contributions to ALWC with the contributions of nuclear, Aitken, accumulation and coarse modes assessed at <1%, 3%, 85% and 12%, respectively, indicating that the contribution of accumulation mode particles to ALWC dominated among all the aerosol particle modes. During clean processes, decreases in relative humidity and PM2.5 both resulted in a decrease in ALWC. During the pollution processes, calm winds caused local particle accumulation, with ALWC increasing as RH increased. Intraday trends in ALWC and relative humidity were consistent, with minimum mean values observed in the afternoon due to low ambient relative humidity inhibiting an increase in ALWC. However, diurnal variation of aerosol hygroscopicity and ALWC tended to be somewhat anti-correlated, indicating that diurnal changes in aerosol hygroscopicity are not a primary factor resulting in ambient AWLC changes.

Impact of relative humidity on visibility degradation during a haze event: A case study.

Light scattering of aerosols depends on ambient relative humidity (RH) since hygroscopic particles absorb significant water at high RH, and this results in low visibility. This paper used custom-made parallel nephelometers (PNEPs) to measure aerosol light scattering enhancement factor ƒ(RH), and utilized data including visibility, PM2.5, black carbon, water-soluble ions mass concentrations and surface meteorological parameters, in conjunction with background weather conditions, to analyze a haze event in Guangzhou during 8th-15th Dec. 2013. Unfavorable weather conditions, such as high RH and low wind speed, were observed during the haze event. The hourly average mass concentration of PM2.5 was 127µg/m(3), with concentration of 192.4µg/m(3) on 9th and 196µg/m(3) on 13th. The ƒ(RH) did not exhibit significant changes during this haze process, with value of ƒ(80%)=1.58±0.07. Although the mass fraction of water-soluble ions to PM2.5 decreased after 12th Dec., the aerosol hygroscopicity might not have changed significantly since the mass fraction of nitrate became more dominant, which has stronger ability to take up water. The best-fitted parameterized function for ƒ(RH) is ƒ(RH)=0.731+0.1375∗(1-RH/100)(-1)+0.00719∗(1-RH/100)(-2). Combining the fixed parameterization of ƒ(RH) above, the visibility was calculated with the measured light scattering and absorption coefficient of particles and gas under dry condition, as well as ambient RH. The predicted visibility range agrees well with the measurements without precipitation. Using ISORROPIA II model, the calculated aerosol liquid water content (ALWC) at ambient RH varied consistently with the PM2.5 under lower RH, while it was more influenced by high RH. This work also show that high RH accompanied with precipitation will enhance aerosol hygroscopic growth effect, leading to further visibility degradation, even if PM2.5 mass decreased due to precipitation.

Multi-level dissolution and hydrolysis of lignocellulosic waste with a semi-flow hydrothermal system.

The hydrothermal process is efficient in lignocellulosic conversion and is beneficial to potential bioethanol production. In batch- and flow-type processes, concurrent dissolution and hydrolysis of lignocellulose result in product loss and inhibitory intermediates. Therefore, multi-level hydrothermal conversion of corn stalks was implemented with a semi-flow system to provide different residence times to undissolved compounds and facilitate dissolution or hydrolysis at respective optimal conditions. First-stage dissolution dissolved amorphous hemicellulose and lignin at 195-200°C. Xylan, acid soluble lignin, and part of Klason lignin were dissolved without affecting glucan. In second-stage dissolution, the crystallinity of the undissolved materials suddenly decreased at 245-250°C. The cellulose dissolution ratio was higher than 75%. Soluble sugars were obtained after the hydrolysis of dissolved cellulose at 280°C. The results provide significant information on the multi-level hydrothermal process and its potential applications for recovering valuable chemicals from lignocellulosic waste.

[Characteristics Analysis of Sulfur Dioxide in Pearl River Delta from 2006 to 2010].

Based on the in-situ SO2 observation dataset from 2006 to 2010 in Pearl River Delta(PRD) , the temporal characteristics of SO2 are analyzed. The results show that the annual average volume fraction of surface SO2 in 2010 declines to a level below average values in recent years, with reducing the frequency of high concentration episodes occurring. The seasonal, monthly and diurnal characteristics of surface SO2 are influenced by particular weather conditions in the PRD. The Probability Distribution Function(PDF) of surface SO2 volume fraction are complicated. The PDF is different every month maybe caused by the variation of the seasonal factors.

Characterization of secondary aerosol and its extinction effects on visibility over the Pearl River Delta Region, China.

Aerosol samples collected from July 2007 to March 2008 were used to obtain major aerosol constituents in an urban location in the Pearl River Delta Region (PRD), China. The minimum organic carbon (OC)/elemental carbon (EC) ratio was used to calculate the primary and secondary organic carbon and the extinction effect of the secondary aerosol on visibility was estimated. As indicated in the analysis, the mass of secondary aerosol takes up 50% of the total mass of PM2.5; the OC/EC ratio is larger than 2 and there are significant characteristics of secondary aerosol generation; the levels of secondary OC are comparable with those of sulfate; and there is obvious enrichment of secondary aerosol on more polluted days. In a dry environment, the extinction weight is 59% for the secondary aerosol, while it is as high as 82% if the environment is highly humid (relative humidity [RH] = 95%). The hygroscopic growth of the aerosol can reduce visibility greatly; the secondary aerosol shares much larger quotas on more polluted days. For the Pearl River Delta (PRD), secondary aerosol and carbonaceous aerosol, especially secondary organic carbon (SOC), are a very acute problem; the study of the generating mechanism and sources for secondary aerosol is the key to the effort of controlling visibility in this region. The equation set forth in IMPROVE experiments can only be referenced but is not applicable to evaluate the extinction effect of individual aerosol components on visibility in the PRD region.

[Study on air quality and pollution meteorology conditions of Guangzhou during the 2010 Asian games].

Based on the monitoring data of NO2, O3, SO2, PM, visibility, regional air quality index (RAQI) and the atmospheric transport and diffusion data from Nov. 4, 2010 to Dec. 10, 2010 in Guangzhou area, the variations of air quality and meteorological conditions during the Guangzhou Asian Games were analyzed. It was found that, during the Asian Games, the air quality was better than the air quality before or after the Asian Games. The visibility was greater than the visibility before or after the Asian Games, while the concentrations of PM1 and PM2.5 were lower. The correlation coefficient between visibility and the concentrations of PM1, PM2.5 indicated anti-correlation relationships. Daily and hourly concentrations of NO2 and SO2 met the primary ambient air quality standards, whereas the daily concentration of PM10 and hourly concentration of O3 met the secondary ambient air quality standards. Pollutants had been well controlled during the Asian Games. The concentration of SO2 in Guangzhou was influenced by local sources and long distance transmission, while the concentration of NO2 was significantly influenced by local sources. The emissions of NO2, SO2 and PM10 surrounding Guangzhou had a trend to affect the concentrations in Guangzhou, but the situation of O3 was opposite, the relatively high concentration of O3 in Guangzhou had tendency to be transported to the surrounding areas. The pollution meteorology conditions in the period of Asian Games were better than the conditions before or after the Asian Games. The decrease in the concentrations during the Asian Games did not only benefit from the emission control by the government, but also from the good meteorological conditions.