Supporting the Scottish Air Quality Monitoring Network during the COVID-19 lockdown

Supporting the Scottish Air Quality Monitoring Network during the COVID-19 lockdown
03 June 2020

Supporting the Scottish Air Quality Monitoring Network during the COVID-19 lockdown

On 16 March 2020, the Government introduced a range of stringent measures to limit the spread of the coronavirus (COVID-19) pandemic. On 23 March, stricter ‘lockdown’ measures were enforced, causing all non-essential business and service providers to shut their doors nationwide. This quick and severe response was due to the known respiratory health conditions associated with COVID-19 and the fast-spreading nature of the virus.

Air pollution is recognised by the World Health Organization (WHO) as a significant risk to human health, and those with existing heart or respiratory conditions are more susceptible to increased health risks associated with air pollution.

Since air pollution can further exacerbate the symptoms of those with pre-existing respiratory conditions, the UK Government and the Scottish Government deemed that maintaining air quality monitoring networks was essential to the ongoing evaluation of risk during the COVID-19 outbreak. Consequently, Ricardo’s air quality team in Scotland has continued its monitoring work throughout the lockdown period, including fieldwork in the form of regular site calibrations and audits. As a result, we have been able to maintain a reliable and up-to-date dataset on the Air Quality in Scotland website, and provide insightful analysis of local air quality data since the start of the COVID-19 outbreak in the UK.

Changes in air quality

The imposition of lockdown measures resulted in fewer vehicles on the road. Some may argue that this would improve air quality and benefit public health, so why worry about air pollution – there should be no problem. Firstly, this assumption simply isn’t true. Air pollution is caused by much more than road transport. Other emitters (illustrated in Figure 1) include agriculture, households, power generation and natural means (e.g. volcanoes and wildfires). In addition, pollutants can be transported or chemically formed as air masses move from one country to another (transboundary pollutants). Undoubtably, there has been a decrease in road traffic emissions since 24 March, especially in densely populated cities. However, other reasons for increased air pollution are still apparent, so continued fieldwork is essential throughout all networks to get a comprehensive understanding of the changes that have occurred.

Figure 1. Sources of Air Pollution

Secondly, the downturn in vehicle emissions gives us a unique opportunity to assess the impact of what might be possible for the ultra-low emission zones of the future, and to consider how things might change as things return to ‘normal’.

On both of these counts it is clear that continued site visits and fieldwork to maintain the ongoing quality of data is essential for the Scottish air quality monitoring networks.


Our air quality field team members have become accustomed to quieter roads during the lockdown and enjoyed not having to sit in rush-hour traffic. As you would expect, the team is taking extra precautions in light of COVID-19 and observing all health and safety guidelines diligently. All vans are fully stocked with hand sanitisers, gloves and anti-bacterial spray. Maintaining business continuity has been challenging for many during this time. However, we have been doing our best to maintain close communications with our clients, partners and subcontractors to minimise disruption to day-to-day work activities and adjust work patterns where necessary. Throughout this time, our field teams have been in almost constant contact with each through virtual meetings. This helps to ensure that there is a period of 72 hours between different teams visiting the same site, so minimising the risk of spreading COVID-19. If a problem develops at a site within 72 hours of a visit, then the team that most recently visited the site will return and rectify any issues, so ensuring analysers are working within their parameters.

Limited time is spent in public places and each van is kitted out with all the equipment the team needs to respond to any callouts, which avoids unnecessary visits to the office. The sites that we visit are located in a mixture of rural and urban environments and the various teams are taking extra precautions to attend the urban-based sites earlier in the day than normal to minimise any public interaction.  

Below are some images from the Scottish field team – noting the eerily quieter roads.

Figure 2. Cathedral Street, Glasgow at 17:00 on a Tuesday

Figure 3. George Square, Glasgow at 17:00 on a Monday

Figure 4. Nicolson St, Edinburgh, 28 April at lunchtime

Figure 5. Duke Street, Glasgow at 17:00 on a Tuesday

Figure 6. M9 at Stirling Castle, 8 May at 07:30

Working from home

In response to Government guidelines, most Ricardo offices were closed in March (except for those offices with laboratories) and all employees packed up their desks and set up space at home to allow for home working. Our IT support team deserves a massive ‘pat on the back’ because of the quick response in expanding our server capacity in a short period of time and enabling everyone to work from home during the lockdown.

Members of our management team also deserve a big thank you because they have been very open to flexible working, which has enabled staff to juggle work commitments with home schooling duties and caring for young and/or elderly relatives. This is all in addition to ensuring the business needs of our clients are still delivered to the highest possible standard, without compromising the wellbeing and safety of our people during the pandemic.

We have now been working at home for over 2 months, and our air quality team members are all looking forward to when they can go back to ’normal’ and return to the office – tea breaks haven’t been the same since lockdown. Although face-to-face catch ups aren’t an option right now, our teams across the UK and internationally have been able to stay in contact virtually and have regular online catch ups. Virtual team quizzes have become quite popular across the business.

Office-based air quality work, although being done at home, has remained a key priority during this period. The air quality team has been ratifying data from monitoring sites, keeping the Air Quality in Scotland website up to date, completing technical reports and investigating the impact of COVID-19.  

Scientifically, the COVID-19 lockdown has created a unique situation for air quality in Scotland. Our air quality team has been carrying out innovative analysis of the data during this time, specifically in cities where volumes of traffic have been lower than normal, to understand exactly what changes in air quality have occurred.

Data analysis

On Monday 4 May, Stephen Stratton, Principal Air Quality Consultant, was featured on BBC Scotland’s news programme. He highlighted the ongoing analysis we were carrying out on the impact of reduced traffic volumes on air pollution levels and described the proven modelling techniques used to discount the influence of weather on ambient pollutant concentrations.

Figure 7. Screenshot of Stephen whilst on BBC Scotland

Ricardo also provided some additional analyses of oxides of nitrogen (NOx) data to the BBC to further illustrate the dramatic decrease in NOx concentrations compared to levels this time last year (Figure 8).

It is somewhat ironic to see this drop in NOx occur in many Scottish cities considering that, in 2017, the Scottish Government committed to introducing low emission zones (LEZs) in Glasgow, Edinburgh, Aberdeen and Dundee by the end of 2020. The LEZs programme, currently delayed due to COVID-19, will be phased into these cities to ensure all commercial and private vehicles (which enter an LEZ) are fully compliant with the requirements of the LEZ emission standards The intention behind any LEZ is to reduce pollution levels and improve air quality in areas where limits are being exceeded.

Figure 8. Decreases in NOx levels from those this time last year – top left clockwise Glasgow, Edinburgh, Aberdeen and Perth monitoring station locations

Figure 8. (top right) clockwise): Glasgow, Edinburgh, Aberdeen and Perth monitoring station locations and decrease in NOx from this time last year

Figure 9 shows the NOx and sulfur dioxide (NO2) concentrations that were measured at the air quality monitoring station at Lochee Road, Dundee. The pink shading indicates the period when social distancing was advised, and green indicates when the lockdown was enforced. Although there are many sources of air pollution in cities, the primary emission is generally NOx from traffic. NO2 will be from a mixture of primary emissions and secondary chemical reactions but is closely linked to local traffic.

Due to the continued hard work of our field team in carrying out site calibrations, Ricardo can accurately scale the air quality monitoring data enabling us to create more reliable analysis.

Figure 9. Measured concentrations at Lochee Road, Dundee

Figure 10 illustrates the modelled NOx from the air quality monitoring site at Lochee Road, Dundee for March and April 2020. As Stephen explained on BBC Scotland, we analyse measured historical NOx and NO2 concentration data from the air quality monitoring site to develop a model that discounts the influence of weather (e.g. wind direction, temperature and wind speed). Figure 10 shows NOx and NO2 measured concentrations from 1 January 2018 to 29 February 2020 to predict NOx concentrations for March 2020. The purple lines mean the model overestimated the concentrations, whereas orange means the model underestimated.

Before 23 March, when lockdown was enforced, there was roughly the same amount of overestimation and underestimation by the model, suggesting that the measured NOx was comparable to the usual levels at this time of the year and under normal business activities. The modelled (i.e. ‘business as usual’ scenario) NOx concentrations are predominately higher than the measured ones from 23 March onwards, which suggests that reduced emissions from traffic and industry are being seen in the measurements.

Figure 10. Simulated NOx concentrations from model versus actual measurement at Lochee Road, Dundee

Analysis for other Scottish cities can be found on the Air Quality in Scotland website.

RapidAir® modelling

As well as analysing the local picture at monitoring sites, we have also used RapidAir, Ricardo’s in-house dispersion modelling and policy support tool to create the following images of the UK. These early outputs present an initial estimate of how concentrations of NO2 have changed across the UK since the introduction of COVID-19 restrictions.

Figure 11. UK RapidAir outputs (click to expand)

Ricardo is undertaking further refinements of RapidAir models focusing on the impacts of the COVID-19 restrictions on air quality and on the potential future impacts of social distancing measures as restrictions are gradually eased. A summary of some of this research, together with further detailed analysis on concentrations of pollutants measured across the UK will be presented in a free webinar that Ricardo is hosting on Monday 8 June. To register or for more information, please click here.

All in all, this has been an extremely difficult time for everyone in the UK and most of the rest of the world. However, despite the challenges, it has been heartening to see the strong working relationships we have, not only within Ricardo, but also with our partners, clients and subcontractors.  

Hopefully, COVID-19 will be contained soon and we can all return to ‘normal’. At that time, we may take a more conscious approach to our own impact on air pollution and the positive health benefits that can be achieved if we abide by ambitious Government targets and initiatives, like LEZs. For now, it’s great to see everyone keeping safe, working together and our team’s commitment and dedication to ensuring that the monitoring networks and projects continue to operate as normal.

Ashleigh Norrie
Air Quality Consultant – Ricardo Energy & Environment

Contains public sector information drawn from Defra, BEIS and the devolved administrations’ websites, and licensed under the Open Government Licence v3.0. Ricardo-AEA Ltd manages UK-AIR and the NAEI on behalf of the UK Government and the Air Quality in Scotland website on behalf of the Scottish Government.’