A method to dynamically constrain black carbon aerosol sources with online monitored potassium

The result of Aethalometer model to black carbon (BC) source apportionment is highly determined by the absorption Ångström exponent (α) of aerosols from fossil fuel combustion (αff) and wood burning (αwb). A method using hourly measured potassium to calculate the αff and αwb values was developed in this study. Results showed that the optimal αff and αwb were 1.09 and 1.79 for the whole dataset. The optimal α values in the diurnal resolution were also calculated with αff and αwb varied in 1.02 –1.19 and 1.71–1.90, respectively. Using the dynamic α values, the Pearson correlation coefficient between BC and potassium from wood burning substantially improved compared to the results derived from the fixed α values. The method developed in this study is expected to provide more reasonable BC source identification results, which are helpful for air quality, climate, and human health modeling studies.

The Toxic Effect of Water-Soluble Particulate Pollutants from Biomass Burning on Alveolar Lung Cells

In 2018, 3.8 million premature deaths were attributed to exposure to biomass burning nanoparticles from wood combustion. The objective of this study was to investigate and compare the toxic effect of wood-combustion-related biomass burning nanoparticles from three different combustion stages (i.e., flaming, smoldering, and pyrolysis) on alveolar lung cells, by studying cell proliferation, and structural and behavioral parameters. A549 lung epithelial cells were treated with 31, 62, 125, 250, and 500 µg/mL of water-soluble particulate pollutants from wood burning, and measured by means of real-time cell analysis, cell imaging, and phase imaging microscopy. At low concentrations (31 and 62 µg/mL), all three types of wood burning samples exhibited no toxicity. At 125 µg/mL, they caused decreased cell proliferation compared to the control. Exposure to higher concentrations (250 and 500 µg/mL) killed the cells. Cell physical parameters (area, optical volume, eccentricity, perimeter, and optical thickness) and behavioral parameters (migration, motility, and motility speed) did not change in response to exposure to wood burning materials up to a concentration of 125 µg/mL. Exposure to higher concentrations (250 and 500 µg/mL) changed cell perimeter, optical thickness for smoldering and flaming particles, and led to decreased migration, motility, and motility speed of cells. In conclusion, all three of the combustion water-soluble organic pollutants were identified as equally toxic by real-time cell analysis (RTCA) results. The parameters describing cell structure suggest that pyrolysis particles were slightly less toxic than others.

Characterization of primary and aged wood burning and coal combustion organic aerosols in an environmental chamber and its implications for atmospheric aerosols

Particulate matter (PM) affects visibility, climate, and public health. Organic matter (OM), a uniquely complex portion of PM, can make up more than half of total atmospheric fine PM mass. We investigated the effect of aging on secondary organic aerosol (SOA) concentration and composition for wood burning (WB) and coal combustion (CC) emissions, two major atmospheric OM sources, using mid-infrared (MIR) spectroscopy and aerosol mass spectrometry (AMS). For this purpose, primary emissions were injected into an environmental chamber and aged using hydroxyl (diurnal aging) and nitrate (nocturnal aging) radicals to reach an atmospherically relevant oxidative age. A time-of-flight AMS instrument was used to measure the high-time-resolution composition of non-refractory fine PM, while fine PM was collected on PTFE filters before and after aging for MIR analysis. AMS and MIR spectroscopy indicate an approximately 3-fold enhancement of organic aerosol (OA) concentration after aging (not wall-loss corrected). The OM:OC ratios also agree closely between the two methods and increase, on average, from 1.6 before aging to 2 during the course of aging. MIR spectroscopy, which is able to differentiate among oxygenated groups, shows a distinct functional group composition for aged WB (high abundance of carboxylic acids) and CC OA (high abundance of non-acid carbonyls) and detects aromatics and polycyclic aromatic hydrocarbons (PAHs) in emissions of both sources. The MIR spectra of fresh WB and CC aerosols are reminiscent of their parent compounds with differences in specific oxygenated functional groups after aging, consistent with expected oxidation pathways for volatile organic compounds (VOCs) of each emission source. The AMS mass spectra also show variations due to source and aging that are consistent with the MIR functional group (FG) analysis. Finally, a comparison of the MIR spectra of aged chamber WB OA with that of ambient samples affected by residential wood burning and wildfires reveals similarities regarding the high abundance of organics, especially acids, and the visible signatures of lignin and levoglucosan. This finding is beneficial for the source identification of atmospheric aerosols and interpretation of their complex MIR spectra.

Society’s Willingness to Pay for Certified Dry Firewood Energy in Chile

Introduction: Air pollution is present in most cities in Chile due to smoke produced from firewood, as happened in many developing countries, generating various health problems among the population. This situation is especially prevalent in all cities in central and southern Chile. To mitigate it, the government implemented several measures, among which are the promotion of the use of certified dry firewood and hourly restrictions on the use of wood-burning stoves for heating according to the peak emissions of particulate matter.Objective: The objective of this study was to determine the willingness to pay for certified dry firewood as a means of reducing environmental restrictions on the use of wood-burning stoves to heat households.Materials and methods: The study used a non-market valuation, specifically contingent valuation, method using a double-bounded dichotomous choice format with the estimation of biprobit econometric models.Results: The results showed that the average individual was willing to pay 12 USD, and extrapolating that to the local population’s willingness to pay yielded an economic value of 3,415,140 USD, which to a certain extent represents the valuation of air pollution damage.Conclusion: Our results showed that people positively valued the use of dry firewood as a payment vehicle to improve air quality and thereby reduce restrictions on the use of certified dry firewood for heating. Therefore, complementary environmental policy measures should be continued to address the problem of air pollution in both the short and long term.