New Strategies for Sampling, Analysing and Understanding Aerosols
Lead Research Organisation:
University of Bristol
Department Name: Chemistry
Abstract
Aerosols are a collection of solid particles of liquid droplets dispersed in air and include smoke, fog, sea spray and pollution particles from vehicles. Particle sizes can range from the nanometre (a millionth of a millimetre) to the millimetre scale. Aerosols influence health, visibility, and climate and are finding increased technological application in the delivery of drugs to the lungs, the engineering of nanostructures through spray drying, and the delivery of fuels for combustion. This research will examine some of the fundamental challenges faced in understanding aerosols.A key to understanding the impact of aerosols on human health is to understand how they are transformed as they are inhaled and exhaled. In the humid environment found within the respiratory tract, water vapour can condense on inhaled particles leading to growth in size. This can influence their depth of penetration into the lungs, with smaller particles penetrating deeper. The targeted delivery of drugs to the lungs may be enhanced by altering their response to a humid environment. Further, the transmission of airborne viruses, such as the influenza virus, may be influenced by the humidity changes on exhalation and inhalation. Similarly, in atmospheric science it is crucial to understand how aerosol particles are influenced by humidity in order to predict the size of cloud droplets. Understanding the change in particle size with humidity is also critical for understanding the ability of particles to scatter and absorb sunlight and their impact on climate. Thus, key themes of this project will be to understand how particles change in size with humidity and their efficiency in scattering and absorbing light.It is also essential to know the chemical composition of particles to interpret their impact on health and the environment, particularly in polluted urban environments, and to understand how particles are chemically changed over time. Water is ubiquitous in our environment and largely regulates the composition of aerosol. However, many chemicals are not soluble in water. This is particularly true for many pollutants such as polycyclic aromatic hydrocarbons, which are considered to be carcinogenic and mutagenic, and for many of the agrochemicals that are used in crop production. Such chemicals may be very soluble and become concentrated in organic liquids. A key theme of this project will be to understand the properties of aerosol droplets that contain both water soluble and insoluble chemicals, and to understand how chemicals can dissolve into the organic phase within an aerosol. Indeed, many of the organic components may undergo chemical reactions in our environment and a further theme will be to explore the chemistry that can occur in aerosol and how it influences aerosol properties. From the delivery of drugs to the lungs, to the evaporation of fuel droplets in combustion, the spray drying of particles, and the growth of particles in the atmosphere, understanding the rate at which particles can change size and composition is also crucial. For example, the processes occurring during the evaporation of a volatile solvent in the use of metered does inhalers critically determine the delivery of active pharmaceuticals to the lungs. The solid structures formed when liquid droplets rapidly evaporate are controlled by how quickly the solvent evaporates in spray drying. Studies of these very rapid processes are a further theme.Finally, there is considerable interest in the analysis and chemical reactions of very small sample volumes, and this has led to the development of lab-on-a-chip technology. Commonly, solutions flow through very small fabricated channels to allow measurements on micro-litre samples. A final theme of this project will be to control reactions in aerosol droplets containing only picolitres of sample, a billionth of cubic centimetre, using laser beams to move particles around and control chemistry.
Organisations
- University of Bristol (Lead Research Organisation)
- Defence Science and Technology Laboratory (Project Partner)
- University of North Carolina at Chapel Hill (Project Partner)
- University of Manchester (Project Partner)
- Beijing Institute of Technology (Project Partner)
- University of Glasgow (Project Partner)
- Syngenta (United Kingdom) (Project Partner)
- GlaxoSmithKline (United Kingdom) (Project Partner)
- University of Hertfordshire (Project Partner)
Publications
Dennis-Smither B
(2012)
Oxidative aging of mixed oleic acid/sodium chloride aerosol particles
in Journal of Geophysical Research: Atmospheres
Dennis-Smither BJ
(2012)
Phase, morphology, and hygroscopicity of mixed oleic acid/sodium chloride/water aerosol particles before and after ozonolysis.
in The journal of physical chemistry. A
Dennis-Smither BJ
(2014)
Volatility and oxidative aging of aqueous maleic acid aerosol droplets and the dependence on relative humidity.
in The journal of physical chemistry. A
Duxbury G
(2011)
Photodissociation of ND3 and ND2H at 193.3nm: Symmetry dependence of the rotational distributions and vibrational excitation of the ND2 () fragment
in Journal of Molecular Spectroscopy
Guillon M
(2009)
Thermo-optical resonance locking of an optically trapped salt-water microdroplet
in New Journal of Physics
Haddrell AE
(2012)
Accounting for changes in particle charge, dry mass and composition occurring during studies of single levitated particles.
in The journal of physical chemistry. A
Haddrell AE
(2014)
Dynamics of aerosol size during inhalation: hygroscopic growth of commercial nebulizer formulations.
in International journal of pharmaceutics
Haddrell AE
(2015)
Dynamics of Particle Size on Inhalation of Environmental Aerosol and Impact on Deposition Fraction.
in Environmental science & technology
Haddrell AE
(2013)
Control over hygroscopic growth of saline aqueous aerosol using Pluronic polymer additives.
in International journal of pharmaceutics
Hargreaves G
(2010)
Measurements of the equilibrium size of supersaturated aqueous sodium chloride droplets at low relative humidity using aerosol optical tweezers and an electrodynamic balance.
in The journal of physical chemistry. A
Description | Through the period of a 5 year fellowship, the following significant conclusions (summarising >50 publications) have been the following. - We have extended the application of optical tweezers in the examination of aerosol processes, including the development of a commercial instrument that has now gone to market. - We have resolved many of the fundamental questions as to the micorphysical processes that govern the evaporation and condensation of liquids, specifically through studying liquid droplets. - We have provide unique data examining the heterogeneous chemical transformation of aerosol and how the chemical changes lead to changes in particle hygroscopicity, refractive index, composition and vapour pressure. - We have demonstrated that individual particles can be captured in a Bessel light beam and probed by cavity ringdown spectroscopy. - We explored the properties of ultraviscous and glassy aerosol, developing a new tool to measure the viscosity of particles over a range of 12 orders of magnitude and a method for examining the kinetics of water transport in viscous particles. |
Exploitation Route | Many of the techniques developed are now being applied to address problems in atmospheric aerosol science funded by grants from the NERC. |
Sectors | Environment Healthcare Other |
Description | As an EPSRC Leadership Fellowship, this funding has allowed Prof. Reid (JPR) to establish an international profile (a key objective of this scheme), leading to additional non-academic impacts. In particular, since the conclusion of the award in 2015: - JPR has been appointed as Editor-in-Chief of the journal Aerosol Science and Technology, the journal of the American Association of Aerosol Research published by Taylor an Francis. - JPR has been President of the UK and Ireland Aerosol Society (20017-2020). - JPR led a successful bid for an EPSRC Centre for Doctoral Training in Aerosol Science involving 7 UK universities and now acts as director. As part of the financial support for this Centre, JPR has secured partnership commitments from 55 non-academic industrial and public sector partners totalling ~£2 million in cash and £2 million in-kind, supporting PhD studentships and mentoring for a total of 80 students across 5 cohorts. - Using the experimental tools developed during the fellowship, JPR has secured PhD studentship funding from DSTL (5 studentships), Chiesi (2 studentships) and IRSN (1 studentship). In addition, Chiesi, DSTL, Steer Energy and Danone have all funded periods of post-doctoral research benefiting from the instrumentation developed during the fellowship. - The commercial instrument developed as a consequence of the Fellowship, the Aerosol Optical Tweezers Instrument, has been sold by Biral to 5 laboratories around the world (US, Germany and China). - The profile established by JPR has positioned him to lead a number of projects tackling the transmission of SARS-CoV-2, in particular studying the risks of transmission associated with singing and exercise (the PERFORM project funded by UKRI EPSRC), the risks of aerosol generating procedures in clinical procedures (the AERATOR project funded by UKRI and NIHR), and the airborne/aerosol survival of SARS-CoV-2 viruses (through the AERATOR project, HSE and MRC). The PERFORM project has informed government guidance on the performing arts during the pandemic (notably the change of guidance in August 2020). The AERATOR project is providing evidence to the NIHR Task and Finish group on the risks of aerosol generating procedures. |
First Year Of Impact | 2009 |
Sector | Environment,Healthcare,Pharmaceuticals and Medical Biotechnology,Other |
Impact Types | Cultural Policy & public services |
Description | A Prototype Aerosol Optical Tweezers Instrument |
Amount | £99,950 (GBP) |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 04/2013 |
End | 08/2014 |
Description | New Frontiers in Aerosol Particle Measurements |
Amount | £333,338 (GBP) |
Funding ID | EP/L010569/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 03/2014 |
End | 03/2017 |
Title | Assessing the Accuracy of Complex Refractive Index Retrievals from Single Aerosol Particle Cavity Ring-Down Spectroscopy |
Description | Cavity ring-down spectroscopy (CRDS) of single, optically manipulated aerosol particles affords quantitative retrieval of refractive indices for particles of fixed or evolving composition with high precision. We quantify the accuracy with which refractive index determinations can be made by CRDS for single particles confined within the core of a Bessel laser beam and how that accuracy is degraded as the particle size is progressively reduced from the coarse mode (> 1 micrometre radius) to the accumulation mode (< 500 nm radius) regime. We apply generalised Lorenz-Mie theory to the intra-cavity standing wave to explore the effect of particle absorption on the distribution of extinction cross section determinations resulting from stochastic particle motion in the Bessel beam trap. The analysis provides an assessment of the accuracy with which the real, n, and imaginary, ?, components of the refractive index can be determined for a single aerosol particle. These data are published in M. I. Cotterell et al., Aerosol Science and Technology (2016) |
Type Of Material | Database/Collection of data |
Year Produced | 2016 |
Provided To Others? | Yes |
Title | Commercial Aerosol Optical Tweezers Instrument |
Description | Developed with Biral through the award of an EPSRC Impact Acceleration Award, the AOT-100 allows users to hold airborne particles for extended periods with ease. Holding particles in an optical trap enables many different parameters (droplet radius, refractive index, composition, phase, morphology etc.) to be studied continuously over times varying from milliseconds to hours. |
Type Of Technology | Physical Model/Kit |
Year Produced | 2014 |
Impact | Sale of first instrument to governmental laboratory in USA |
URL | http://www.biral.com/particle-aerosol-analysers/aerosol-optical-tweezers |
Description | American Association of Aerosol Research Plenary Lecture |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited plenary talk |
Year(s) Of Engagement Activity | 2013 |
Description | American Chemical Society Fall Conference |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited Talk |
Year(s) Of Engagement Activity | 2012 |
Description | American Geophysical Union Conference |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited Talk |
Year(s) Of Engagement Activity | 2012 |
Description | Berkeley Atmospheric Sciences Symposium |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited talk |
Year(s) Of Engagement Activity | 2013 |
Description | Seminars at ETH-Zurich (Switzerland), University of Kyoto (Japan), and York (UK) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited talks |
Year(s) Of Engagement Activity | 2013 |
Description | University of California, Irvine |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited talk at University |
Year(s) Of Engagement Activity | 2013 |
Description | University of California, San Diego |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Talk at University |
Year(s) Of Engagement Activity | 2013 |
Description | Workshop on Physical Chemistry of Aerosol |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited Talk |
Year(s) Of Engagement Activity | 2014 |
Description | Workshop on Physical Chemistry of Aerosol |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Invited talk |
Year(s) Of Engagement Activity | 2012 |