Indoor airborne particle sources and outdoor haze days effect in urban office areas in Guangzhou.

To identify the sources of PM2.5 pollutants in work environments and determine whether the air quality inside an office was affected by a change in outdoor pollution status, concurrent indoor and outdoor measurements of PM2.5 were conducted at five different office spaces in the urban center of Guangzhou on low pollution days (non-episode days, NEDs), and high pollution days (haze episode days, EDs). Indoor-outdoor relationships between the PM2.5 mass and its chemical constituents, which included water-soluble ions, carbonaceous species, and metal elements, were investigated. A principle component analysis (PCA) was performed to further confirm the relationship between the indoor and outdoor PM2.5 pollution. The results reveal that (1) Printing and ETS (Environmental tobacco smoking) were found to be important office PM2.5 sources and associated with the enrichment of SO42-, OC, EC and some toxic metals indoors; (2) On EDs, serious outdoor pollution and higher air exchange rate greatly affected all studied office environments, masking the original differences of the indoor characteristics (3) Fresh air system could efficiently filter out most of the outside pollutants on both NEDs and EDs. Overall, the results of our study suggest that improper human behavior is associated with the day-to-day generation of indoor PM2.5 levels and sporadic outdoor pollution events can lead to poor indoor air quality in urban office environments. Moreover, fresh air system has been experimentally proved with data as an effective way to improve the air quality in office.

[Possible Sources of PCDD/Fs in Atmosphere of a Certain District in Guangdong].

This paper analyzed 17 polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) by HRGC/HRMS in the flue gas of a certain municipal solid waste incinerator(MSWI) and its surrounding air and other possible sources in Guangdong. It discussed the feature of homologs and main toxic monomers in all samples. It also investigated the relationship among surrounding area, MSWI and possible sources using principle component analysis (PCA) and cluster analysis. The results showed that the concentration of PCDD/Fs was higher in the flue gas than the ambient air, moreover non-effect suffered by prevailing wind direction. The possible sources might be tyre factory and open burning based on spot survey. The concentration of PCDD/Fs was lower in tyre factory than upwind station, but higher at open burning spot than outdrop monitoring station. The analysis of homologs showed that OCDD, 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8-HpCDF were the main materials in the flue gas and air, meanwhile OCDF was also found in atmosphere. There was similar feature of 17 PCDD/Fs between surrounding monitoring station and tyre factory, and the same between flue gas and open burning. The further analysis showed that the linearly dependent coefficients of 1,2,3,7,8-PeCDD and 2,3,4,6,7,8-HxCDF were 0.95 and 0.75, respectively. It showed the strong correlation of two monomers in all ambient air samples. The PCA and cluster analysis showed that MSWI influenced the surrounding air, tyre factory had an impact on upwind station, and open burning had a lower effect on outdrop monitoring station.

Airborne PCDD/Fs in two e-waste recycling regions after stricter environmental regulations.

Since the 2010s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) after stricter environmental regulations. PM2.5 and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32pgTEQ/(kg•day), which far exceeded the tolerable daily intake (TDI) limit (1-4pgTEQ/(kg•day). Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.

[Emission of PCDD/Fs from Crematories and Its Influencing Factors].

To analysis the influencing factors for the emssions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) as structure of crematory, air pollution control device (APCD) and funeral objects, etc, we collected and measured the PCDD/Fs emissions in flue gas from 13 crematories in China. Then we proposed some supervision suggestions on measures of pollution control and management. The results indicated that the emission levels of PCDD/Fs (as the toxic equivalent concentration, TEQ) was ranged in a large gap from 0.027 to 15.8 ng x m(-3), and the average was 3.2 ng x m(-3). Emissions factor of PCDD/Fs (as TEQ) from 13 crematories varied between 45.9 and 22 236 ng x body(-1), and the average was 4 738 ng x body(-1). The emissions of PCDD/Fs from flat incinerators were generally lower, whereas higher ratio up to the national discharge standard, than that of car type incinerators. Congener distribution of PCDD/Fs in flue gas from 13 crematories were different from each other. Since the emission of PCDD/Fs from some crematories remains in high level, it is necessary to control pollution from the source, improve the pollution control technology, and strengthen government supervision, by following measures: 11 cremating funeral objects separately from corpse; 22 adding one

Influence of a municipal solid waste incinerator on ambient air PCDD/F levels: a comparison of running and non-running periods.

The concentration of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the ambient air of a municipal solid waste incinerator (MSWI) during its running and non-running periods was monitored in this study to investigate the contribution of the MSWI to PCDD/F pollution in the vicinal environment. Results show that the PCDD/F levels for the normal MSWI running period and after shut-down ranged 0.156-1.44 pg I-TEQ/m(3) (0.514 pg I-TEQ/m(3)) and 0.158-0.648 pg I-TEQ/m(3) (0.345 pg I-TEQ/m(3)), respectively. Significant differences were found between the results of the two surveys in 2011 and 2012. High PCDD/F levels were observed in two of the seven study sites in 2011, and these levels directly declined in 2012. A dramatic increase in PCDD/F concentrations was observed in two sites in 2012. Comparison of congener and homologue fingerprint characteristics in the two surveys, together with principal component analysis, revealed that the PCDD/F levels in all of the samples collected in 2012 and in three of the samples collected in 2011 are mainly influenced by heavy traffic. MSWI is the primary PCDD/F emission sources of the PCDD/Fs detected in the remaining samples collected in 2011.

[Concentration, profile distribution and source identification of PCDD/Fs in environmental medium around a HSWI].

The concentration and profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the environmental air, soil and plant samples around a hospital solid waste incinerator (HSWI) in Northwest of China were determined by HRGC/HRMS, and the flue gas samples of the HSWI were also involved. The results showed that the average concentration (I-TEQ) of PCDD/Fs in the exhaust gas was 184 ng x m(-3), which seriously exceeds the emission standard (0.5 ng x m(-3)). And the average concentration of PCDD/ Fs was 7.30 pg x m(-3) in the ambient air samples, 52.5 pg x g(-1) in the soil samples, and 146 pg x g(-1) in the leaves samples. All of them were at quite high levels. The concentrations of PCDD/Fs in air samples of downwind were obviously higher than those of upwind. The concentration increased and then decreased with the increase of distance from the HSWI, and the highest concentration occurred at the distance of 700 m from the HSWI. The mass concentration (I-TEQ) proportional distributions of 2, 3, 7, 8 substitution toxic dioxins in downwind air and soil samples was similar to those in the exhaust gas samples. The analysis results of PCDD/Fs concentrations, profiles distributions and principal components all showed that the major source of PCDD/Fs in this area was from the HSWI flue gas emissions.