Aerosol mixing state matters for particles deposition in human respiratory system

Abstract

Aerosol particles emitted from various human activities deteriorate air quality and are suggested to increase public health risk. Numerous studies have emphasized the relationship between the mass and/or number concentration of aerosols (or commonly known as particulate matter (PM)) in the atmosphere and the incidence of respiratory and cardiovascular diseases, while very few have examined the deposition efficiency of inhaled particles in the respiratory tract. We present the first examination of particles deposition based on, detailed simulation of aerosol physico-chemical properties by a recently developed particle-resolved aerosol model and the mixing state dependent hygrosocpic growth and deposition computed at particle-level by deposition model. Furthermore, we elucidate the impact of mixing state on deposition efficiency by using a recently introduced aerosol mixing state index. We find that without considering mixing-state-dependent hygroscopic growth of particles leads to overestimation of deposition efficiency; whereas considering an average mixing state leads to underestimation of 5% to 20% of soot particle deposition efficiency in human alveoli. We conclude that aerosol mixing state, which evolves during the interaction between atmospheric chemistry and meteorology, is important for the comprehensive evaluation of air quality and its implication to public health requires further investigation.

Aerosol mixing state revealed by transmission electron microscopy pertaining to cloud formation and human airway deposition

“…Detailed single particle analysis contributes to aerosol model development and evaluation to explore the underlying interplay between emission, meteorology and chemistry governing the physicochemical properties evolutions, the highly uncertain aerosol-cloud-climate interaction and the associated impacts on climate 5,11,45 and air quality. 13,14 This consequently benefits air quality prediction, and pollution mitigation policy devising and aligns with one of the emphases in the theme of sustainable development. 46,47…”

“…[8][9][10] These impacts depend on the aerosol physicochemical properties, which require detailed studies (i) to reduce the uncertainty in aerosol-cloud-climate interactions, one of the largest uncertainties in climate projection; 5,11 and (ii) to understand the various aerosol impacts on human health. [12][13][14] Numerous studies of laboratory experiments, field observations, and model simulations have examined aerosols to understand their fundamental properties, atmospheric transformation and impacts on climate and human health.…”

“…Curtis et al, 31 developed particle-resolved aerosol representation in single column mode of WRF-Chem meteorology-chemistry coupled model to simulate vertical distribution of mixing state. Recently, Ching and Kajino 14 evaluated the mixing state impact on particle deposition efficiency in the human respiratory tract by developing particle-resolved deposition model.…”

Adverse organogenesis and predisposed long-term metabolic syndrome from prenatal exposure to fine particulate matter

“…The transport of fine PM from air to fetus is not fully understood. Although ultrafine particles contribute only to a small fraction of the total ambient PM mass, they are typically present in high concentrations in the urban atmosphere (3,(29)(30)(31) and have a high probability to deposit in the pulmonary system after inhalation than large particles (32,33). Through blood circulation and endocytosis, ultrafine particles likely enter organs beyond the lungs, such as the reproductive tract, heart, liver, spleen, kidneys, brain, and BAT (34,35).…”

Characterising Mass-resolved Mixing State of Black Carbon in Beijing Using a Morphology-Independent Measurement Method

“…Bondy et al (2018) performed a microscopy study on air samples collected from the south-eastern United States, and they found that most of the accumulation mode particles are internally mixed when the secondary organic aerosol concentration is high, and most of them are externally mixed during dust events. As one of the large mega-cities in China, Beijing has suffered from heavy air pollution (Yang et al, 2005) and is likely to have many factors affecting BC mixing state, which in turn has implications for both air quality and climate (Ching and Kajino, 2018). These aerosols can have a global reach (Liu et al, 2015) and as their effects may be influenced by dynamic effects near the point of emission where concentrations are highest, an polluted urban environment represents a good location to investigate these behaviours and properties.…”