Recent News

Implications of the COVID-19 pandemic on air quality monitoring and assessments


Government health guidance restricting non-essential travel, working from home and self-isolation during the current COVID-19 pandemic will impact our professional activities and so the Institute of Air Quality Management (IAQM) provides the following information.

Employers have a duty of care for their employees and employed IAQM members should follow their organisation’s advice as appropriate. Whether members are employed or self-employed the Government’s instructions and guidance must be followed.

This note relates to the impact on, and the subsequent use of, data collected during the period of travel restrictions.

Potential issues

There are a number of potential issues regarding data collected in the coming months:
  1. Disruptions to long- and short- term monitoring programs;
  2. Impact on input data used for modelling;
  3. The protocol for passive monitoring such as diffusion tubes; and
  4. Misleading information on the impacts of the COVID-19 pandemic on air quality.

Advice relating to these matters

This information is relevant as of the 6th of April 2020 and may be updated if the opinion of IAQM changes.

Monitoring surveys

Construction sites 
Construction dust monitoring programmes using automatic monitors should continue. Calibration/cleaning/maintenance may be restricted. Individuals should follow government and, employer’s guidance as appropriate if carrying out a physical visit. If construction sites shut down temporarily there may be no need for monitoring, although monitoring during the period may provide useful information regarding the baseline.

Automatic ambient air quality monitoring
Automatic monitoring sites can continue without site visits in most cases. Where site visits are required for maintenance, routine servicing or audits these may be delayed and data may be affected. It is understood, the national networks including the Automatic Urban and Rural Network (AURN) and the UK Urban NO2 Network (UUNN) are continuing as they are essential to track the impact of reduced activity on pollution levels, and provide information to the public.

Data collected from automatic monitoring sites goes through a quality control procedure and then ratified. This ratification process should account for data reliability and so it follows that ratified automatic monitoring data should be reliable. Ratified data may be delayed because site audits and servicing are likely to be later than scheduled.

Passive tube monitoring
It is unlikely that site visits can occur and laboratories providing tubes are beginning to close, meaning exposed tubes cannot be analysed and new tubes are not available. It is unlikely that tube changeover will occur on the designated days and monitoring periods may be longer than the ~4 week period recommended. Tubes have a shelf life (preparation to analysis) of between 6 weeks and 4 months (depending on pollutant). Diffusion tubes can become saturated or degraded if left out for longer. Nevertheless, it may be useful if the tubes are left out for the duration of the restricted travel period. Where tubes are collected and cannot be immediately analysed it is recommended that they be stored in line with the laboratory guidelines and analysed when possible. The data may be usable but with reduced confidence, depending on the length of the pandemic restrictions. Data collected from monitoring surveys which span the restricted travel period may not be representative of the typical longer term concentrations.

It is understood that monitoring carried out as part of the UUNN is continuing as expected, although will be kept under review.

The national bias adjustment factors published by Defra could potentially take account of the extended period of exposure where the diffusion tube site has been in place for a long-term prior to the travel restrictions. Comparisons with automatic monitors may enable adjustment factors to be applied to provide useable data provided the data limitations are clearly stated.

Model input data

It is good practice to use traffic, meteorological and air quality monitoring data for the same year when verifying models.

The travel restrictions will have an impact on some modelling input parameters e.g. traffic data. Traffic data are often adjusted to a previous year (i.e. 2018 or 2019) and, therefore, caution needs to be applied when using 2020 traffic data in future models derived for traffic surveyed in other years, as it may not be representative of the traffic, and traffic in 2020 will mostly be less than would have been the case without the restrictions.

Modelling typically uses the previous year’s annual monitoring data. Data from 2020 will need to be used with caution and may not be useable.

Pandemic ‘effects’ on air quality 

There will be many studies in the coming weeks on the impact of the pandemic on air quality, many of which may not adequately take account of the confounding factors, particularly the meteorological conditions. As with any robust air quality analysis multiple variables need to be considered and direct comparison of snap shots of data (e.g. Week 1 March 2020 compared to Week 1 March 2019) is likely to be misleading.

Analysis of ‘provisional’ monitoring data in the short-term should be treated with caution, should be clearly stated that data are provisional and revisited once ratified data are available.

Members should not spread misinformation regarding the effects of the pandemic based on poor science.


Protection of your own health and the health of others is of the utmost importance.

We are experiencing an extremely unusual situation but it is essential that members continue to exercise their professional skills diligently and adjust to the changed circumstances.

IAQM Members should always use their professional judgement when undertaking air quality assessments or providing advice on air quality. However, given what are likely to be significant gaps in data, or less robust data during the travel restriction period, consideration should be given to either postponing or repeating any assessments or studies that require inputs likely to be compromised by this atypical situation.

IAQM recommends that the passive tubes exposed during the lockdown period and travel restrictions are analysed when possible rather than discarded and at which time validity is reviewed.
Share this post