The aethalometer — An instrument for the real-time measurement of optical absorption by aerosol particles

Hansen, A. D. A.; Rosen, H.; Novakov, T.

doi:10.1016/0048-9697(84)90265-1

Cited by 991 publications

(572 citation statements)

References 9 publications

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“…As the principle behind using an aethalometer for BC determination has been described elsewhere (Hansen et al 1984;Jeong et al 2004;Lavanchy et al 1999), only a brief description will be provided here. The aethalometer samples ambient air through a quartz filter tape at a flow rate of 5 L/min.…”

Section: Determination Of Bcmentioning

confidence: 99%

“…According to the literature, both EC and BC are considered to assume a graphitic structure and are therefore thermally refractory and light-absorbing in nature (Bond and Bergstrom 2006;Salako et al 2012;Conny et al 2003;Turpin et al 1990). It seems that both EC and BC describe nearly the same fraction of carbonaceous aerosols; however, according to traditional practice, their values are dependent on specified determination methods which focus on different properties, e.g., thermal stability or light absorption (Birch 1998;Chow et al 1993;Hansen et al 1984). This practice introduces the potential for disagreement between EC and BC measurements due to method-involved biases (Jeong et al 2004;Lavanchy et al 1999;Li et al 2006;Salako et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Zhi

Chen

Xue

et al. 2014

Environ Monit Assess

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Studies specifically addressing the elemental carbon (EC)/black carbon (BC) relationship during the transition from clean-normal (CN) air quality to heavy haze (HH) are rare but have important health and climate implications. The present study, in which EC levels are measured using a thermal-optical method and BC levels are measured using an optical method (aethalometer), provides a preliminary insight into this issue. The average daily EC concentration was 3.08±1.10 μg/m 3 during the CN stage but climbed to 11.77±2.01 μg/m 3 during the HH stage. More importantly, the BC/EC ratio averaged 0.92±0.14 during the CN state and increased to 1.88± 0.30 during the HH state. This significant increase in BC/ EC ratio has been confirmed to result partially from an increase in the in situ light absorption efficiency (σ ap ) due to an enhanced internal mixing of the EC with other species. However, the exact enhancement of σ ap was unavailable because our monitoring scheme could not acquire the in situ absorption (b ap ) essential for σ ap calculation. This reveals a need to perform simultaneous measurement of EC and b ap over a time period that includes both the CN and HH stages. In addition, the sensitivity of EC to both anthropogenic emissions and HH conditions implies a need to systematically study how to include EC complex (EC concentration, OC/EC ratio, and σ ap ) as an indicator in air quality observations, in alert systems that assess air quality, and in the governance of emissions and human behaviors.

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Section: Determination Of Bcmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Zhi

Chen

Xue

et al. 2014

Environ Monit Assess

View full text Add to dashboard Cite

show abstract

“…It is important to recognize that surrogate measures of EC, such as BC measurements (Hansen et al, 1984;Bond et al, 1998Bond et al, , 1999, do not have exact correlations with either the NIOSH EC or IMPROVE EC measurements. For this reason, atmospheric measurements of BC should not be used as a direct measure of EC.…”

Section: Measurements Of Ecmentioning

confidence: 99%

Evaluation of elemental carbon as a marker for diesel particulate matter

Schauer

2003

J Expo Sci Environ Epidemiol

217

123

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Elemental carbon (EC) in atmospheric particulate matter originates from a broad range of sources in many urban locations. As health and air quality studies are using elemental carbon measurements to better understand the impact of diesel engines and other combustion sources, there is a great need to clearly understand the relative source contributions to EC concentrations in the atmosphere. However, the different analytical techniques currently used to measure EC do not show good agreement for many particulate matter samples. To this end, studies that use EC as a tracer and integrate different analytical techniques for EC can significantly bias estimates of source contributions to atmospheric particulate matter. In addition, source attribution studies that do not properly address all sources of EC in the atmosphere can also lead to inaccuracies and biases. To better understand the use of EC as a tracer, a review of the distribution of EC in the primary particulate matter emissions from air pollution sources using different analytical methods is discussed. A review of previous apportionment studies of particulate matter is presented to elucidate the fraction of EC that results from emissions from diesel engines in urban locations. These results demonstrate that EC is not a unique tracer for diesel exhaust and efforts to utilize EC as an indicator of diesel exhaust must properly address other sources of EC as well as utilize a consistent measurement technique for EC when comparing source and ambient EC measurements to avoid significant biases.

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“…Within these periods, several weeks were devoted to intensive measurements that included 12-hour filter-based measurements of particle chemistry, constant measurements of ventilation rates, and manual manipulation of the conditions in the house. The intensive periods were October 9-23, December 11-19, 2000 and January [16][17][18][19][20][21][22][23]2001. During these periods, entry into the house was limited to an approximately one-hour period at midday during which instrument checks, flow calibrations, and filters changes were performed.…”

Section: Sampling Sitementioning

confidence: 99%

Use of Time- and Chemically Resolved Particulate Data To Characterize the Infiltration of Outdoor PM_2.5 into a Residence in the San Joaquin Valley

Lunden

Thatcher

Hering

et al. 2003

Environ. Sci. Technol.

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Recent studies associate particulate air pollution with adverse health effects. The indoor exposure to particles of outdoor origin is not well characterized, particularly for individual chemical species. In response to this, a field study in an unoccupied, singlestory residence in Clovis, California was conducted. Real-time particle monitors were used both outdoors and indoors to quantity PM2.5 nitrate, sulfate, and carbon. The aggregate of the highly time-resolved sulfate data, as well as averages of these data, was fit using a time-averaged form of the infiltration equation, resulting in reasonable values for the penetration coefficient and deposition velocity. In contrast, individual values of the indoor/outdoor ratio can vary significantly from that predicted by the model for time scales ranging from a few minutes to several hours. Measured indoor ammonium nitrate levels were typically significantly lower than expected based solely on penetration and deposition losses. The additional reduction is due to the transformation of ammonium nitrate into ammonia and nitric acid gases indoors, which are subsequently lost by deposition and sorption to indoor surfaces. This result illustrates that exposure assessments based on total outdoor particle mass can obscure the actual causal relationships for indoor exposures to particles of outdoor origin.

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The aethalometer — An instrument for the real-time measurement of optical absorption by aerosol particles

Cited by 991 publications

References 9 publications

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Evaluation of elemental carbon as a marker for diesel particulate matter

Use of Time- and Chemically Resolved Particulate Data To Characterize the Infiltration of Outdoor PM_2.5 into a Residence in the San Joaquin Valley

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The aethalometer — An instrument for the real-time measurement of optical absorption by aerosol particles

Cited by 991 publications

References 9 publications

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Evaluation of elemental carbon as a marker for diesel particulate matter

Use of Time- and Chemically Resolved Particulate Data To Characterize the Infiltration of Outdoor PM2.5 into a Residence in the San Joaquin Valley

Contact Info

Product

Resources

About

Use of Time- and Chemically Resolved Particulate Data To Characterize the Infiltration of Outdoor PM_2.5 into a Residence in the San Joaquin Valley