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Citizen science for monitoring air pollution

Learn about this 3-step approach used to engage local communities in monitoring air pollution levels, providing new insights into human health and how to mitigate and avoid pollutants using a citizen science approach.
Multiple Authors
A tower in misty skies in Kuala Lumpur, Malaysia
Photo by Ishan @seefromthesky on Unsplash

This tool is part of theSEI Urban Toolbox for Liveable Cities which has been developed by theSEI Initiative on City Health and Wellbeing.The Urban Toolbox isa collection of tools, developed within SEI or in coordination with SEI,aimed at supporting planning and decision-making for improving the health, well-being and resilience of city residents and urban systems more broadly.


About this tool

Air pollution remains a major environmental, health, and policy challenge in both developed and developing countries, particularly those that are rapidly urbanizing. The primary pollutant of concern for human health is fine particulate matter (PM). Aiming to engage local communities in monitoring and tackling air pollution, this approach uses three interconnected methods:

  • A personal mobile exposure monitoring campaign to measure particulate matter
  • A questionnaire conducted before and after the monitoring campaign, to assess any changes in knowledge
  • Workshops to facilitate the citizen science approach

*The Urban Toolbox article below uses key messages from the open access paper “Particulate matter pollution in an informal settlement in Nairobi: Using citizen science to make the invisible visible” published in Applied Geography, 114, under the CC By 4.0 license in January 2020 © West et al. Please note that references have been removed.For much more detail, research purposes, full references, and to quote text you can access the paper from the right-hand column.

How does this tool work?

This approach combines three interlinked methods, which together can provide local communities, policymakers and scientists with new insights into the challenges air pollution poses for human health in urban settlements, and opportunities for exploring how to monitor, mitigate and avoid these pollutants using a citizen science approach. Citizens are central to this approach, actively participating in the measuring of air pollutants; identifying potential problem areas and solutions; and fostering dialogues with important stakeholders to catalyse change.

Who might use this tool?

Local community members, researchers, policymakers, urban planners

Which stakeholders are involved?

Local residents in urban settlements, and other key local stakeholders (researchers, policymakers, local authorities)

What stage of the process does this tool support?

  • Identifying environmental issues (e.g. the source of pollutants)
  • Identifying and implementing solutions
  • Fostering dialogues and discussions among stakeholders
  • Generating ideas and knowledge (e.g. raising awareness among local communities)
  • Monitoring

Tool overview

Citizen science is the partnering of scientists and non-scientists to work together to answer scientific questions (Dickinson et al., 2012). This approach is collaborative, in which participants and stakeholders are engaged in planning, design and implementation. This can allow incorporation of local knowledge into the scientific process and ensure that research is focused on issues of concern to local residents.


Stage 1 – monitoring particulate matter:

The first stage of this approach requires low cost air quality monitors (for example Dylos or PurpleAir) which are battery-powered, low-cost particle counters. These monitoring devices use a light-scattering technology, have been tested both indoor and outdoor by scientists and community members. A calibration of these devices through co-location with a high-precision stationary PM measuring device is important, as is the cross-calibration of all devices used in a campaign. Monitoring can be at a fixed location or mobile, where participants carry the monitor around, usually in an adapted backpack.

During the personal monitoring campaigns in the Nairobi case study, alongside each Dylos was a GPS Trackstick (Telespial Systems Inc, California, USA), a lightweight (82g) device which every 10 s records date, time, latitude and longitude, altitude, speed, direction and temperature. These, in combination with the Dylos, are carried around by community members as they go about their daily routine. This is important to ensure the monitoring reflects levels of PM2.5 actually experienced by community members on a daily basis.

Stage 2 – questionnaire:

In order to assess whether participation has an impact on people (for example, their knowledge, attitude or behaviours), evaluation can be conducted. In this case study, we used a structured questionnaire, conducted face-to-face with a convenience sample of members of the local community, with a non-representative mix of ages (between 18 and 55) and genders. The questionnaires can be conducted by research assistants recruited from the local community, with support from experienced researchers as required.

The questionnaire used in this approach comprised 13 questions, focusing on people’s perception of air quality in their area (indoor and outdoor), knowledge of the sources of air pollution, where they had previously heard about air pollution, and whether they thought they can influence their exposure to pollution. Questions concerning sources of air pollution should be based on questionnaires developed for, or information specific to the study area in question if possible.

Stage 3 – workshops:

Project workshops can be carried out to engage stakeholders. A project inception workshop aims to raise awareness of the project, and to gain feedback from stakeholders on the study design. Mechanisms for collaboration among different stakeholders and a common understanding of the study approach and objectives can then be developed.

Once the project has reached completion, another workshop is conducted. This is done to (1) encourage the sharing of knowledge and experiences between different actors, and specifically to increase understanding among experts and environmental agencies of studies and initiatives that had been undertaken in the study area on air quality; (2)provide a forum for community members, scientists and policy-makers to discuss the findings, interpret the data, and to give people a better understanding of the experiences of those living in the urban area; (3)identify actions for stakeholders on data collection and research, policy formulation and implementation, and education, information and public awareness; and (4) find a mechanism for ongoing collaboration to achieve these actions.

Application: citizen science case study examples

Using citizen science to monitor particulate matter pollution in an informal settlement in Nairobi, Kenya: This case study demonstrates how this approach can be used in an urban settlement context, and highlights how it is able to raise awareness and catalyse further community action.

Capabilities and resources required


  • This collaborative approach requires the support of experienced researchers to both train community participants and local research assistants; and also facilitate the workshop dialogues.
  • Key local stakeholders (e.g. policymakers, urban planners etc.) also need to be identified and connected with the local community.


  • Access to and knowledge on how to use air quality monitors (e.g. Dylos, PurpleAir) and GPS tracksticks are required for this particular approach.
  • The questionnaire used in this approach can be found in Appendix A of the featured download, and can be adapted to the study area accordingly.

Implementation tips: key enablers and potential barriers

Key enablers for this approach include:

  • Training community ‘champions’ or participants to use the equipment and a set of instructions on how to operate them.
  • Obtaining oral consent from participants in the questionnaire, rather than written consent, encouraged a more diverse and inclusive range of participants.
  • Community ‘champions’ (who do not typically have a stable income) should be paid to encourage their participation.

Potential barriersand how they can be mitigated are as follows:

  • Dylos sensors only have a 6 hour battery life and require up to 12 hours to fully recharge – this can lead to a loss of data if there are power outages.
  • Participants’ activity logs may be completed with insufficient detail, in turn making the interpretation of data less reliable – more regular contact with community participants and access to urban background data could mitigate this.
  • Use of low-cost particle counters and the conversion of their particle numbers to a PM concentration does introduce uncertainty with respect to absolute PM concentrations as compared to the direct measurement of these concentrations with stationary high-precision devices.
  • Highly variable micro-meteorological conditions that are typical for low-latitude environments do tend to influence the precision of low-cost PM sensors – this can be mitigated by designing measurement campaigns in collaboration with community members to test the impact of particular locations and activities on personal exposure.

Potential integration with other tools

This approach could be integrated with other participatory-based tools, such as participatory GIS, as well as surveys (e.g. focusing on perceptions of the local environment) to add depth to the results and opportunities for data comparison.

Suggested Citation:

West, S.E., Büker, P., Ashmore, M., Njoroge, G., Welden, N., Muhoza, C., Osano, P., Makau, J., Njoroge, P. and Apondo, W. (2020). Particulate matter pollution in an informal settlement in Nairobi: Using citizen science to make the invisible visible. Applied Geography, 114,

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