• 期刊
• OpenAccess

Evaluation and Correction of the Ambient Particle Spectral Light Absorption Measured Using a Filter-based Aethalometer

Spectral light-absorption properties measured with an Aethalometer (AE; Model AE33; Magee Scientific) are widely used in radiative forcing studies and source appointment in China. However, considerable uncertainty regarding the measured absorption coefficient (σ_(abs)) exists because of the multiple-scattering effects, loading effects, and differences in filter tape. This study evaluated σ_(abs) by comparing the values measured with an AE33 using Tape 8050, an AE33 using Tape 8060 (which differs from Tape 8050 in material), and a three-wavelength photoacoustic soot spectrometer (PASS-3) during two field campaigns in eastern China. The results indicated that the AE33-measured σ_(abs) using either tape exceeded the PASS-3-measured value by approximately three times, mainly owing to the multiple-scattering effect. A wavelength-independent multiple-scattering compensation factor (2.90), which varies slightly (± 0.04) for eastern China, is recommended for these regions. When σ_(abs) was measured with the AE33 using Tape 8050, the value highly depended on the loading on the tape, which led to significant uncertainty and discontinuity in the absorption Ångström exponent compared to using Tape 8060. A method was proposed to effectively correct the historical datasets of σ_(abs) and the absorption Ångström exponent by using the AE33 with Tape 8050. This work provides insight into the quality of measured absorption data when filter-based measurement technology is applied.

• 期刊
• OpenAccess

Associations between Personal Exposure to Metals in Fine Particulate Matter and Autonomic Nervous System Dysfunction among Healthy Adults

The impact of airborne particulate matter and its metal components on autonomic nervous system (ANS) dysfunction in healthy subjects remains unclear. The aim of this study was to examine the effects of personal exposure to airborne particulate matter on the ANS in young, healthy adults. This longitudinal study recruited 82 adults aged 20 to 35 years from districts A and B. District A had lower ambient PM_(2.5) levels than district B. Personal exposure to fine particulate matter and metals in PM_(2.5) was collected every two months. The heart rate variability (HRV) indices of each participant were measured three times. The relationship among the PM_(2.5) concentration, metals in PM_(2.5) and HRV level was investigated by a generalized estimating equation with an autoregression of order 1. The average age of the participants was 26.4 ± 3.6 years in district A and 21.9 ± 1.5 years in district B (p ＜ 0.001). After adjusting for covariables, significant changes in Log_(10) standard deviation of normal to normal (SDNN) intervals and Log_(10) square root of the mean of the sum of the squares of differences (r-MSSDs) were related to unit changes in Log_(10) iron in PM_(2.5) (β = -0.033, 95% CI = -0.060 to -0.0056, p ＜ 0.05 and β = -0.041, 95% CI = -0.075 to -0.0076, p ＜ 0.05, respectively). The Log_(10) SDNN levels were significantly positively related to Log_(10) gallium in PM_(2.5) (β = 0.054, 95% CI = 0.0064 to 0.10, p ＜ 0.05). Exposure to heavy metals in airborne particulate matter was associated with ANS dysfunction.