Citizen Science In Merton: A walk exploring how communities can participate in creating healthier environments

On Saturday 23rd March 2024, we held a free public walk with the environmental charity Sustainable Merton and Merton Council, exploring how citizen science projects in the borough can help connect communities to their physical environment and raise awareness of local air quality and nature. Our event was also part of Natural England’s 2024 Happier Outdoors festival, promoting connection to green spaces and nature in Greater London.

In recent years, citizen science has become an increasingly popular activity, helping local communities understand the quality of the environment where they live and become advocates for creating healthier neighbourhoods. Citizen science (other names include “community science”, “crowd-sourced science”, “civic science”, “participatory monitoring”, or “volunteer monitoring”) is when research is carried out with participation from the general public. At its most inclusive and most innovative, citizen science involves local people as partners throughout the entire research process, alongside professional scientists or practitioners. Communities may be actively involved in mapping air pollution hotspots in the local area, collecting and analysing data, or even identifying and carrying out actions which improve air quality.

Building upon the learnings of our recent IMPETUS citizen science project in Stockwell, this walk provided an opportunity to explore and celebrate the value of community participation in scientific research initiatives and continue the discussions about how to help engage people in improving environmental quality in cities.

Event Summary

Our event involved a tranquil stroll from Wimbledon Broadway to Morden Town Centre, avoiding air pollution hotspots and exploring local nature habitats. With the (mostly) sunny weather on our side, over 30 people attended. This included environmental scientists, local residents and their relatives, school teachers, and a representative from the Air Quality team at Merton Council. Our walk also attracted people from other emerging citizen science air quality networks in London, as far as Ealing!

We explored different citizen science projects, including Sustainable Merton’s air quality project with Merton Council & Breathe London, involving local volunteers, residents, schools and businesses in the collection and monitoring of Nitrogen Dioxide (NO2 ) on main roads and side streets. We also encouraged participants to look out for the citizen science equipment used in air quality monitoring, for example NO2 diffusion tubes and solar powered sensors. Later on in the walk, we also explored other creative uses of citizen science, in understanding the health of local waterways such as the River Wandle and protecting unique wildlife in local green spaces such as Deen City Farm and Morden Hall Park.

Tranquil City Walk – the walking route through Merton with our Tranquil City Index background layer. Our Tranquil City Index shows the potential for a location to be good for our wellbeing. The index considers data such as noise pollution, traffic, air quality and access to nature and weights them based on their ability to have a restorative effect.

Before and after the walk, we also carried out a mini questionnaire to assess each participant’s self-reported happiness and relaxation.

Out of the 16 respondents who completed the survey, on average, the happiness score increased by 27% and relaxation score by 59%.

Dr Eleanor Ratcliffe, Environmental Psychologist at Tranquil City & University of Surrey
Keywords describing respondents’ experiences of the walk.

Alongside testimonials from walking tour attendees, fantastic feedback was received from our event partners.

Outdoor walks like these are so important as the positivity on display, helping people to make better choices about walking routes and showing them that “behind the scenes” there is a network of Council employees and volunteers working together to help monitor air quality, really does fill residents with hope and reassures them that there are many people actively working to improve our planet. 

Danila Ardé, Operations & Volunteers Manager at Sustainable Merton

Wimbledon Broadway – Managing air quality with the local Council and communities

Starting at Wimbledon Broadway, we spoke about what citizen science is and Merton Council’s growing interest in such activities. In the latest 5 Year Air Quality Plan, the local council notes that there is a growing interest from community groups and individuals to be involved in air quality monitoring and reporting. Alongside sparking interest and raising awareness, citizen science can be invaluable, tapping into local residents’ lived experiences and knowledge of air pollution hotspots in the area. We also touched on Sustainable Merton and Merton Council’s brilliant citizen science work, setting up a wide network of over 30 NO2 diffusion tubes and over 20 solar-powered sensors across the borough, collecting continuous data on air quality.

We huddled by Wimbledon Broadway, to discuss different lived experiences of air pollution in the city and the role of citizen science activities in increasing our knowledge of such challenges.
A representative from Merton Council, showing us what an air quality monitoring sensor looks like!
Walking tour participants stumbling across one of the NO2 diffusion tubes outside a local school.

South Park Road – Choosing quieter routes can reduce exposure to pollution

Taking a slight detour from the main high street, we took a stroll along a residential side street – South Park Road. Here, we spoke about our exciting project with the Cross River Partnership. In 2020, we were commissioned by the Cross River Partnership to help identify 16 Clean Air Routes in London for walking and cycling. South Park Road forms a small part of one Clean Air Route, which offers an alternative way of getting from Wimbledon Station to South Wimbledon Station. On average, levels of Nitrogen Dioxide are 23% lower, compared to walking along Broadway and Merton Road. This demonstrates the power of how small daily habit changes can meaningfully reduce our exposure to pollution but also can boost our mood and wellbeing.

We used handheld air quality monitors to assess where the Clean Air Routes were, compared to the “fastest” options. Using our environmental datasets, we also selected routes with less exposure to noise and more greenery.

Pelham Road (Public Walkway) – Encouraging use and safety of local alternative routes

Continuing along the Clean Air Route to South Wimbledon Station, we momentarily paused by the public walkway on Pelham Road. Here, we reflected upon our latest Natural England research work, done in collaboration with the University of Surrey & Go Jauntly. We specifically talked about what design features can encourage the use of alternative routes and increase feelings of safety. From our research, we found that the connectivity of alternative routes in the local area was important for increasing use and accessibility to a wide range of demographics, but also for safety. Good maintenance of trees, vegetation, plant diversity and water features along these routes was also key in increasing feelings of safety, along with lighting and the presence of community wardens.

The tranquil public walkway on Pelham Road, which weaves between a series of residential backyards.

Nelson Gardens – Benefits of nature on wellbeing

Rejoining the main road at South Wimbledon Station and continuing further South, we stumbled across the peaceful Nelson Gardens. At this stop, we discussed the many benefits of green spaces, including psychological restoration. Reflecting on the research work of our latest team member, Dr Eleanor Ratcliffe, sensory experiences from seeing nature, to hearing bird song or even smelling the scent of flowers, can help to improve mental wellbeing, and foster a deeper connection to local green spaces. Excitingly, Ellie is joining our team for a year, as part of an Innovation Fellowship funded by the British Academy.

At Nelson Gardens, new team member, Ellie spoke about her latest research exploring wellbeing benefits of local green spaces.

The River Wandle – Citizen science and the health of local waterways

Walking past various schools down to the end of High Path Road, we met with the River Wandle. Stopping opposite the historic Merton Abbey Mills, we spoke about other creative uses of citizen science, helping local communities understand the health and quality of local rivers, a very poignant topic given the recent news about sewage overspills threatening water quality and biodiversity across the UK. We spoke about a number of trailblazing citizen science projects happening in the UK, including Thames 21’s work with volunteers, surveying dragonfly numbers on the Crane Park Island nature reserve in Twickenham and carrying out litter clean-ups across the capital to remove plastic waste from rivers. We also reflected on the successes of the annual Bristol Avon WaterBlitz (now RiverBlitz), enabling those passionate about their local green and blue environment to continue contributing to its conservation.

Standing opposite Merton Abbey Mills, we spoke about the history of the River Wandle and its rich freshwater biodiversity.
The extensive River Wandle, which runs from Wandsworth all the way to East Croydon.

Deen City Farm – Citizen science and biodiversity monitoring

Following parallel to the waterway along the Wandle Trail, we crossed past Deen City Farm. Similarly, we looked at other ways of using citizen science to nurture connection and a greater appreciation of the wildlife in our cities. We touched on a few national-scale citizen science events, including the annual Big Butterfly Count, aimed at helping us assess the health of our environment by simply counting the amount and type of butterflies (and some day-flying moths) we see. The BTO Garden BirdWatch is another increasingly popular weekly wildlife survey that anyone can participate in. On a more local level in the Merton area, one walking tour participant warmly shared their knowledge of the Hedgehog Surveys being carried out by the Friends of Mitcham Common.

Morden Hall Park – The history of green spaces in London and discovering tranquillity

Continuing along the Wandle Trail to our final destination, our walking tour ended in the vast National Trust Morden Hall Park. Here, we spoke about the unique history of the park (home to 18th century snuff mills, wartime hospitals, and now a series of community facilities including a cafe and rose garden!) and the continuously changing ownership of parks. Despite their ample benefits, there are still lots of local green spaces around London without public access. Reflecting on the origins of Tranquil City and our evolving manifesto, we continued to discuss the benefits of opening up access, enabling more people to experience tranquillity in a face-paced city.

We strolled along Modern Hall Park’s iconic Wetland Boardwalk!
Momentarily, we paused to reflect upon the what tranquillity is and where to find it in the city.


Citizen science continues to be an increasingly popular activity, helping communities to understand complex topics such as environmental quality and contribute to research on big urban issues like air pollution, noise and limited access to nature. However, citizen science still has its challenges, for example, the equipment used is usually cheap to make them accessible and sometimes people’s lived experiences do not match the data collected. To maximize its potential, there is a strong need to calibrate low-cost monitoring equipment with high-quality, reference grade monitors, ensuring greater validity and accuracy of results. Local councils and practitioners should also explore the use of mixed research methods to get a fuller picture of local environmental quality.


If you would like to receive a copy of the walking route in an alternative format, please do not hesitate to drop a message to

Keep it tranquil!

The Tranquil City Collective

Author: Chloe McFarlane