Project highlights

  • The COVID-19 lockdown changed the atmospheric composition, which caused a widespread and unexpected perturbation to the fundamental state of our contemporary troposphere, increasing overall atmospheric reactivity, oxidant levels and hazardous ultrafine particles.
  • This unprecedented change in the state of our atmosphere has wide ranging consequences in terms of impact on air quality, health and climate, and offers an ideal ‘window’ into the future to scenario model the potential move to a carbon neutral future.
  • This project will be centred around the execution and delivery of discovery science, exploring fundamental chemical mechanics of the atmosphere in terms of ‘next-generation’ radical chemistry and oxidative capacity, routes to ultrafine particle formation and the role of particulate matter in its suppression.


The COVID-19 pandemic forced governments around the world to impose restrictions on daily life to prevent the spread of the virus. This resulted in unprecedented reductions in anthropogenic activity, and reduced emissions of certain air pollutants, namely oxides of nitrogen. The UK ‘lockdown’ was enforced in March 2020, which led to restrictions on movement, social interaction, and ‘non-essential’ businesses and services. Such dramatic reduction in certain air pollutants across the species emissions spectrum, over such a relatively short time interval and across so many different countries, is unprecedented. Much focus has been on improvements in air quality, owing to a reduction in road transport and hence NOx and particulate matter (PM) emissions; however, the picture is not as simple as first thought. Indeed, reductions in NOx emissions have resulted in a perturbation to the ‘normal’ state of lower atmospheric chemistry, which has resulted in an increase in atmospheric reactivity and the photochemical production of ozone (Wyche et al., 2020), which in terms of its function as a respiratory pollutant, has been shown to be a more harmful than NOx species. Further, the reductions observed in ambient PM levels has implications for ultrafine particles (UFP), i.e. PM acts to supress UFP (and hence control their number, as shown in recent research by Guo et al., 2020). This is particularly concerning as UFP are now believed to be more harmful than other, larger fractions of particles; indeed, evidence is mounting to demonstrate their ability to penetrate deeply into the body and impair the function of our major organs.

The project will look to answer the following research questions:

  1. What changes have occurred in atmospheric trace composition and reactivity owing to the COVID-19 lockdown and does this represent a window into the future to see the impact of reduced NOx emissions in moving towards a low carbon economy? What lessons can be learnt and how can these be used to help develop policy and measures to protect the environment and public health?
  2. Do reduced PM concentrations under ‘real-world’/pandemic conditions lead to an increase in UFP numbers and if so to what extent?
  3. Is there a link between UFP (and other air pollutants) and COVID-19 cases?


University of Leicester


  • Climate and Environmental Sustainability


Project investigator

  • Prof. Paul S. Monks



  •  Dr. Steven Ball
  • Dr. Kevin Wyche (University of Brighton)

How to apply


Advance atmospheric datasets (inc. UFP number concentration, size distribution, surface etc) will be gathered from, and recorded in real-time at, two dedicated research monitoring sites. These historic and current data will be combined with observations gathered by satellite (Sentinel 5P) and outputs derived from state-of-the-art chemical models (MCM) and fed into an ensemble of advanced quantitative data analysis methods employing Geographical Information Systems and a range of statistical decomposition and dimension reduction techniques to explore how the COVID-19 lockdown affected atmospheric composition and reactivity, and how this scenario may represent a future where NOx emissions from vehicles have been reduced. Geospatial analysis of the atmospheric composition data will also be integrated with geo-referenced population statistics and reported COVID-19 cases to produce ‘risk/exposure maps’, and to investigate linkages between UFP (and other air pollutants) with instances of the virus.

Training and skills

The student will join the Atmospheric Chemistry Group at the University of Leicester (approx 20 people) and thereby benefit from the group’s extensive expertise in trace gas detection methods, data analysis techniques, atmospheric modelling, field work skills and logistics planning. Targeted training will be given to operate relevant instrumentation available in the group. In addition to the CENTA training, we offer lecture courses that are directly relevant to the project: e.g. Earth System Science.

Partners and collaboration

University of Brighton, School of Environment and Technology

National Centre for Earth Observation (NCEO) – Satellite data Elements

Further details

Potential applicants are welcome to discuss the project informally and obtain further information from the project supervisors:

Prof Paul Monks ( – Department of Chemistry, University of Leicester, Leicester LE1 7RH.

Dr. Kevin Wyche ( – School of Environment and Technology, University of Brighton, BN2 4GJ.

Possible timeline

Year 1

Generic CENTA training and training specific to this project. The student will be taught the fundamental principle of, and how to operate and maintain, a range of advanced atmospheric monitoring equipment, namely ultrafine particle counters and surface area monitors, differential optical absorption spectroscopy, multiangle absorption photometers, particle samplers, proton transfer reaction mass spectrometers and gas chromatography mass spectrometry. The student will also be taught how to analyse atmospheric data and use key software, including R (OpenAir), SNAP and ENVI (for Sentinel 5P), ArcGIS (geospatial analysis) and ADMS and Fortran (for modelling). The student will also conduct extensive literature analysis to underpin their project and advance their fundamental understanding of the subject area.

Year 2

Conduct a year-long time series of ambient observations in Leicester and Brighton, measuring a full suite of atmospheric parameters using the advanced instrumentation studied in Year 1. Begin gathering and analysis of historic data (collected during the initial COVID-19 lockdown) and begin chemical modelling of the atmosphere under a range of pre, during and post COVID-19 scenarios. Conduct an initial ensemble analysis of historic in-situ data, satellite data and public health statistics (including instances of COVID-19) using a range of advanced statistical and geospatial techniques to address the research questions.

Year 3

Conclude analysis of historic data and integrate with data measured during the Year 2 intensive. Conclude on effects of the COVID-19 lockdown on atmospheric composition and reactivity. Determine whether linkages exist between changes in atmospheric composition under reduced NOx scenarios and secondary pollutants (inc. O3) and UFP. Determine whether linkages exist between air pollutants and (increased) instances of COVID-19. Explore linkages to policy.

Further reading

[1] Monks, P.S. (2020) Coronavirus: lockdown’s effect on air pollution provides rare glimpse of lowcarbon future? Available at:

[2] Wyche, K. P., Nichols, M., Parfitt, H., Beckett, P., Gregg, D. J., Smallbone, K. L. & Monks, P. S. 2020. Changes in Ambient Air Quality and Atmospheric Composition and Reactivity in the South East of the UK as a Result of the COVID-19 Lockdown. Science of The Total Environment, 142526.

[3]  T. Le, Y. Wang, L. Liu, J. Yang, Y.L. Yung, G. Li, J.H. Seinfeld (2020) Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China, Science, 369 (6504) 702-706.



The project has a high degree of COVID resilience as it can be executed by a mixture of desk-based and field-based research.  Much of the data for the COVID full lockdown has already been collected.  There will be some laboratory characterisation that can be conducted under COVID-safe laboratory working procedures.