Zhihua Tina Fan

Environmental and Occupational Health Sciences Institute, Edison, New Jersey, United States

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Publications (8)20.37 Total impact

  • Lihui Huang · Chang Ho Yu · Philip K. Hopke · Jin Young Shin · Zhihua (Tina) Fan
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    ABSTRACT: Measurement of carcinogenic Cr(VI) in ambient PM is challenging due to potential errors associated with conversion between Cr(VI) (a carcinogen) and Cr(III) (an human trace essential nutrient). Cr(III) conversion is a particular concern due to its >80% atomic abundance in total Cr. USEPA 6800 method that uses water-soluble isotope spikes can be used to correct the inter-conversion. However, whether the enriched Cr(III) isotope spikes can adequately mimic the Cr(III) species originally in ambient PM is unknown. This study examined the water-solubility of Cr(III) in ambient PM and discussed its influence on Cr(VI) measurement. Ambient PM10 samples were collected on Teflon filters at four sites in New Jersey that may have different Cr emission sources. The samples were ultrasonically extracted with 5 mL DI-H2O (pH=5.7) at room temperature for 40 min, and then analyzed by IC-/ICP/MS. Cr(III) was below detection limit (0.06 ng/m3) for all samples, suggesting water-soluble Cr(III) species, such as CrCl3, Cr(NO3)3 and amorphous Cr(OH)3, in the ambient PM was negligible. Therefore, the enriched 50Cr(III) isotope spike (in the form of Cr(NO3)3) could not mimic the original ambient Cr(III). Only the conversion of 53Cr(VI) (in the form of K2CrO4) was taken into account when correcting the inter-conversion. We then used NaHCO3-pretreated MCE filters (pre-spiked with enriched isotope species) to measure Cr(VI) in the ambient PM10. The samples were ultrasonically extracted at 60 C pH~9 solutions for 40 min followed by IC/-ICP/MS analysis. Due to the correction of Cr(VI) reduction, the Cr(VI) concentrations determined by USEPA 6800, 0.26 +- 0.16 (summer) and 0.16+-0.11(winter) ng/m3 (N=64), were significantly greater than those by the external standard curve, 0.21+-0.17 (summer) and 0.10+-0.07 (winter) ng/m3 (N=56) (p < 0.01, Student’s t t-test). Our study revealed that appropriate application of USEPA 6800 is important because it only applies to soluble fraction of Cr species in ambient PM.
    Journal of the Air & Waste Management Association 11/2014; 64(12):1439-1445. DOI:10.1080/10962247.2014.951745 · 1.67 Impact Factor
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    ABSTRACT: Hexavalent chromium (Cr(VI)) in ambient airborne particulate matter (PM) is a known pulmonary carcinogen and may have both soluble and insoluble forms. The sum of the two forms is defined as total Cr(VI). Currently, there were no methods suitable for large-scale monitoring of total Cr(VI) in ambient PM. This study developed a method to measure total Cr(VI) in ambient PM. This method includes PM collection using a Teflon filter, microwave extraction with 3% Na2CO3-2% NaOH at 95°C for 60 minutes, and Cr(VI) analysis by 1,5-diphenylcarbazide colorimetry at 540 nm. The recoveries of total Cr(VI) were 119.5 ± 10.4% and 106.3 ± 16.7% for the Cr(VI)-certified reference materials, SQC 012 and SRM 2700, respectively. Total Cr(VI) in the reference urban PM (NIST 1648a) was 26.0 ± 3.1 mg/kg (%CV = 11.9%) determined by this method. The method detection limit was 0.33 ng/m3. This method and the one previously developed to measure ambient Cr(VI), which is soluble in pH ~9.0 aqueous solution, were applied to measure Cr(VI) in ambient PM10 collected from three urban areas and one suburban area in New Jersey. The total Cr(VI) concentrations were 1.05–1.41 ng/m3 in the winter and 0.99–1.56 ng/m3 in the summer. The soluble Cr(VI) concentrations were 0.03–0.19 ng/m3 in the winter and 0.12–0.37 ng/m3 in the summer. The summer mean ratios of soluble to total Cr(VI) were 14.3–43.7%, significantly higher than 4.2–14.4% in the winter. The winter concentrations of soluble and total Cr(VI) in the suburban area were significantly lower than in the three urban areas. The results suggested that formation of Cr(VI) via atmospheric chemistry may contribute to the higher soluble Cr(VI) concentrations in the summer.
    Aerosol and Air Quality Research 03/2014; 14(7). DOI:10.4209/aaqr.2013.10.0312 · 2.66 Impact Factor
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    ABSTRACT: Hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) are the primary chromium oxidation states found in ambient atmospheric particulate matter. While Cr(III) is relatively nontoxic, Cr(VI) is toxic and exposure to Cr(VI) may lead to cancer, nasal damage, asthma, bronchitis, and pneumonitis. Accurate measurement of the ambient Cr(VI) concentrations is an environmental challenge since Cr(VI) can be reduced to Cr(III) and vice versa during sampling. In the present study, a new Cr(VI) sampler (Clarkson sampler) was designed, constructed, and field tested to improve the sampling of Cr(VI) in ambient air. The new Clarkson Cr(VI) sampler was based on the concept that deliquescence during sampling leads to aqueous phase reactions. Thus, the relative humidity of the sampled air was reduced below the deliquescence relative humidity (DRH) of the ambient particles. The new sampler was operated to collect total suspended particles (TSP), and compared side-by-side with the current National Air Toxics Trends Stations (NATTS) Cr(VI) sampler that is utilized in the US. Environmental Protection Agency (EPA) air toxics monitoring program. Side-by-side field testing of the samplers occurred in Elizabeth, NJ during the winter and summer of 2012. The average recovery values of Cr(VI) spikes after 24-hr sampling intervals during summer and winter sampling were 57 and 72%, respectively, for the Clarkson sampler while the corresponding average values for NATTS samplers were 46% for both summer and winter sampling, respectively. Preventing the ambient aerosol collected on the filters from deliquescing is a key to improving the sampling of Cr(VI).
    Journal of the Air & Waste Management Association (1995) 11/2013; 63(11):1313-23. DOI:10.1080/10962247.2013.823894 · 1.17 Impact Factor
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    ABSTRACT: The inter-conversion between Cr(VI), a pulmonary carcinogen, and Cr(III), an essential human nutrient, poses challenges to the measurement of Cr(VI) in airborne particles. Chamber and field tests were conducted to identify the factors affecting Cr(VI)-Cr(III) inter-conversion in the basic filter medium under typical sampling conditions. In the chamber tests, isotopically enriched 53Cr(VI) and 50Cr(III) were spiked on diesel particulate matter (DPM) and secondary organic aerosol (SOA) that were pre-collected on a basic MCE filter. The filter samples were then exposed to clean air or the air containing SO2 (50 and 160 ppb), 100 ppb O3, or 150 ppb NO2 for 24 hours at 16.7 LPM flow rate at designated temperature (20 and 31ºC) and RH (40% and 70%) conditions. Exposure to 160 ppb SO2 had the greatest effect on 53Cr(VI) reduction, with 53Cr(VI) recovery of 31.7 ± 15.8% (DPM) and 42.0 ± 7.9% (SOA). DPM and SOA matrix induced 53Cr(VI) reduction when exposed to clean air while reactive oxygen species in SOA could promote 50Cr(III) oxidation. Deliquescence when RH increased from 40% to 70% led to conversion of Cr(III) in SOA, whereas oxidized organics in DPM and SOA enhanced hygroscopicity and thus facilitated Cr(VI) reduction. Field tests showed seasonal variation of Cr(VI)-Cr(III) inter-conversion during sampling. Correction of the inter-conversion using USEPA method 6800 is recommended to improve accuracy of ambient Cr(VI) measurements.
    Environmental Science & Technology 04/2013; 47(9). DOI:10.1021/es3046247 · 5.48 Impact Factor
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    ABSTRACT: Assessment of the health risks resulting from exposure to ambient polycyclic aromatic hydrocarbons (PAH) is limited by a lack of environmental exposure data among the general population. This study characterized personal exposure and ambient concentrations of PAH in the Village of Waterfront South (WFS), an urban community with many mixed sources of air toxics in Camden, New Jersey, and CopeWood/Davis Streets (CDS), an urban reference area located ∼1 mile east of WFS. A total of 54 and 53 participants were recruited from non-smoking households in WFS and CDS, respectively. In all, 24-h personal and ambient air samples were collected simultaneously in both areas on weekdays and weekends during summer and winter. The ambient PAH concentrations in WFS were either significantly higher than or comparable to those in CDS, indicating the significant impact of local sources on PAH pollution in WFS. Analysis of diagnostic ratios and correlation suggested that diesel truck traffic, municipal waste combustion and industrial combustion were the major sources in WFS. In such an area, ambient air pollution contributed significantly to personal PAH exposure, explaining 44-96% of variability in personal concentrations. This study provides valuable data for examining the impact of local ambient PAH pollution on personal exposure and therefore potential health risks associated with environmental PAH pollution.
    Journal of Exposure Science and Environmental Epidemiology 03/2011; 21(5):437-49. DOI:10.1038/jes.2011.2 · 3.05 Impact Factor
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    ABSTRACT: This study characterized the time-location pattern of 107 residents living in air pollution hotspots, the Waterfront South and Copewood/Davis Streets communities in Camden, NJ. Most residents in the two communities are minority and impoverished individuals. Results showed that employment status played the fundamental role in determining time-location patterns of this study population, and the variations of time-location pattern by season and by day-type were partially attributed to employment status. Compared to the National Human Activity Pattern Survey, the Camden cohort spent significantly more time outdoors (3.8 hours versus 1.8 hours) and less time indoors (19.4 hours versus 20.9 hours) than the general US population, indicating a higher risk of exposure to ambient air pollution for the Camden cohort. The findings of the study are important for understanding exposure routes and sources for the socioeconomically disadvantaged subgroup and ultimately help develop effective strategies to reduce community exposure to ambient air pollution in "hotspots".
    Journal of Environmental and Public Health 04/2010; 2010:625461. DOI:10.1155/2010/625461
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    ABSTRACT: The spatial variations of volatile organic compounds (VOCs) were characterized in the Village of Waterfront South neighborhood (WFS), a "hot spot" for air toxics in Camden, NJ. This was accomplished by conducting "spatial saturation sampling" for 11 VOCs using 3500 OVM passive samplers at 22 sites in WFS and 16 sites in Copewood/Davis Streets (CDS) neighborhood, an urban reference area located ∼1000 m east of the WFS. Sampling durations were 24 and 48 h. For all 3 sampling campaigns (2 in summer and 1 in winter), the spatial variations and median concentrations of toluene, ethylbenzene, and xylenes (TEX) were found significantly higher (p < 0.05) in WFS than in CDS, where the spatial distributions of these compounds were relatively uniform. The highest concentrations of methyl tert-butyl ether (MTBE) (maximum of 159 μg m(-3)) were always found at one site close to a car scrapping facility in WFS during each sampling campaign. The spatial variation of benzene in WFS was found to be marginally higher (p = 0.057) than in CDS during one sampling campaign, but similar in the other two sampling periods. The results obtained from the analyses of correlation among all species and the proximity of sampling site to source indicated that local stationary sources in WFS have significant impact on MTBE and BTEX air pollution in WFS, and both mobile sources and some of the stationary sources in WFS contributed to the ambient levels of these species measured in CDS. The homogenous spatial distributions (%RSD < 24%) and low concentrations of chloroform (0.02-0.23 μg m(-3)) and carbon tetrachloride (0.45-0.51 μg m(-3)) indicated no significant local sources in the study areas. Further, results showed that the sampling at the fixed monitoring site may under- or over-estimate air pollutant levels in a "hot spot" area, suggesting that the "spatial saturation sampling" is necessary for conducting accurate assessment of air pollution and personal exposure in a community with a high density of sources.
    Atmospheric Environment 10/2008; 42(32):7329-7338. DOI:10.1016/j.atmosenv.2008.07.039 · 3.28 Impact Factor
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    ABSTRACT: There are evidences for exposure to vehicular emissions and adverse cardiopulmonary health effects. This study attempted to further explore these effects on elderly. This study monitored personal PM(2.5) concentrations and ambulatory electrocardiograms continuously for 24 h on 1 working day in 3 separate weeks for 11 school crossing guards. Spirometry was also performed before and after the morning shift. The traffic at each work location was video recorded during one of the three morning shifts. The increases in the average personal PM(2.5) concentrations (baseline PM(2.5) was subtracted) of 1.2-87 and 1.1-98 microg/m(3) were observed during the 1-h morning (DeltaPM(2.5-ave-m)) and afternoon shift (DeltaPM(2.5-ave-a)), respectively. Traffic count was not a significant predictor of the DeltaPM(2.5-ave-m) (P=0.78). Mean heart rate variability (HRV), measured as 5-min standard deviation of normal-to-normal (SDNN) beats during the 10-min rest periods, decreased 18-26% (P<0.02) 15 min, 2 and 4 h after the morning shift, but changes in SDNN (DeltaSDNN) were insignificant post-afternoon exposure (-0.3 to -7% with P>0.53). DeltaSDNN were negatively associated with DeltaPM(2.5-ave-m), with the strongest association at 2 h after the morning shift (P<0.01) but insignificant 4 h after the morning exposure. The peak PM(2.5) concentration (DeltaPM(2.5-peak), baseline PM(2.5) was subtracted) was not a significant predictor for DeltaSDNN, and no clear effect of PM(2.5) exposure on heart rate was observed. There was no effect of PM exposure on lung function (P>0.16), either. In conclusion, acute exposure to the PM(2.5) resulting from mobile sources can cause acute decline in HRV in healthy older adults, suggesting one of the biological mechanisms for the adverse cardiovascular health effects associated with traffic-related air pollution. Traffic count may not be an appropriate surrogate measure of acute personal exposure to vehicular emission in traffic congested areas.
    Journal of Exposure Science and Environmental Epidemiology 10/2008; 19(5):525-33. DOI:10.1038/jes.2008.46 · 3.05 Impact Factor

Publication Stats

61 Citations
20.37 Total Impact Points

Institutions

  • 2008–2014
    • Environmental and Occupational Health Sciences Institute
      Edison, New Jersey, United States
  • 2011–2013
    • Rutgers, The State University of New Jersey
      • Environmental and Occupational Health Sciences Institute
      Нью-Брансуик, New Jersey, United States
  • 2008–2010
    • Robert Wood Johnson University Hospital
      Нью-Брансуик, New Jersey, United States