Can we achieve atmospheric chemical environments in the laboratory? An integrated model-measurement approach to chamber SOA studies.

Secondary organic aerosol (SOA), atmospheric particulate matter formed from low-volatility products of volatile organic compound (VOC) oxidation, affects both air quality and climate. Current 3D models, however, cannot reproduce the observed variability in atmospheric organic aerosol. Because many SOA model descriptions are derived from environmental chamber experiments, our ability to represent atmospheric conditions in chambers directly affects our ability to assess the air quality and climate impacts of SOA.

Compositional Constraints are Vital for Atmospheric PM Source Attribution over India.

India experiences some of the highest levels of ambient PM aerosol pollution in the world. However, due to the historical dearth of in situ measurements, chemical transport models that are often used to estimate PM exposure over the region are rarely evaluated. Here, we conduct a novel model comparison with speciated airborne measurements of fine aerosol, revealing large biases in the ammonium and nitrate simulations.

Rate of atmospheric brown carbon whitening governed by environmental conditions.

Biomass burning organic aerosol (BBOA) in the atmosphere contains many compounds that absorb solar radiation, called brown carbon (BrC). While BBOA is in the atmosphere, BrC can undergo reactions with oxidants such as ozone which decrease absorbance, or whiten. The effect of temperature and relative humidity (RH) on whitening has not been well constrained, leading to uncertainties when predicting the direct radiative effect of BrC on climate.

Updated World Health Organization Air Quality Guidelines Highlight the Importance of Non-anthropogenic PM.

The World Health Organization recently updated their air quality guideline for annual fine particulate matter (PM) exposure from 10 to 5 μg m, citing global health considerations. We explore if this guideline is attainable across different regions of the world using a series of model sensitivity simulations for 2019. Our results indicate that >90% of the global population is exposed to PM concentrations that exceed the 5 μg m guideline and that only a few sparsely populated regions (largely in boreal North America and Asia) experience annual average concentrations of <5 μg m.