On the streets of Accra, the things that threaten people’s health are not always visible.Traffic moves through the city, rubbish accumulates at the roadside, and smoke rises from burning waste. People walk, work and exercise through it all, often without knowing what is in the air they are breathing.A youth-led initiative is trying to make some of that invisible pollution visible.Called Roots and Routes, the project combines health walks with air-quality monitoring and tree planting as part of efforts to raise awareness about air pollution and push for action in Ghana.The name captures its two main approaches: the roots represent trees planted to help improve the environment, while the routes represent the paths taken by participants as they walk through parts of Accra, collecting data on the air around them.“Essentially a project that seeks to create awareness and then take action for clean air under the World Economic Forum’s Clean Air Collaborative,” said Dr Jonathan Caleb Akuaku, the project lead.Walking through Accra’s polluted spacesThe project began with an assessment of Ghana’s air-quality standards, according to Dr Akuaku, before moving into a more practical phase of mapping routes and collecting data.So far, the team has completed two of four planned health walks.The first covered about eight kilometres around Accra’s central business district, including Independence Square.The second took participants through Nima, Kanda and the Independence area, covering a little more than five kilometres.But these are not simply walks for exercise.Participants carry AirBeam sensors supplied by partner organisation Ever and Better, using the devices to measure the quality of the air as they move through different parts of the city.“These devices help us go on this while we’re on the walk, we’re collecting data about the air around us,” Dr Akuaku said.The sensors measure fine particulate matter, including PM2.5 — tiny particles that can remain suspended in the air and be inhaled without being seen.For the team, the value of the walks is therefore not only in getting people moving. Each route becomes an opportunity to gather evidence about the environments through which people live and work.The project plans to collect data from about four different areas, allowing the team to compare air quality and build a clearer picture of how pollution varies across the city.Why air pollution?For Dr Akuaku, the decision to focus on air pollution is closely tied to its consequences for young people.He cited World Economic Forum findings indicating that one in four young people die prematurely because of the harmful effects associated with air pollution.He also pointed to respiratory illnesses linked to poor air quality.“The goal is to live long and healthy life. And so if there’s something that is taking the lives of young people prematurely, that it needs attention. That’s why air pollution is on our radar so strong,” he said.The concern is particularly relevant in rapidly growing urban areas, where transport, waste and construction can all affect the air people breathe.In Accra, the sources highlighted by the project include vehicle emissions, open burning of rubbish and uncollected waste.These are problems residents encounter daily, but their health consequences can be difficult to see or immediately connect to the air around them.From the streets into schoolsRoots and Routes is also taking its message into schools.The project plans to work with five schools, engaging students in discussions about air pollution while helping them plant trees.“We are going into the schools to help them to create more awareness, engage them, help them understand what is happening, then partner with them to build or to plant trees,” Dr Akuaku said.The target is to reach at least 500 students and plant at least 153 trees across the participating schools by October.The intention is to make young people participants rather than simply recipients of information.The walks show them how pollution can be measured. The school activities introduce them to practical environmental action.Together, the two approaches are intended to turn an abstract issue — air quality — into something young people can observe, measure and respond to.Turning measurements into pressure for changeThe project’s organisers say the data will ultimately have to travel beyond the people carrying the sensors.After completing the four planned walks, the team intends to organise a policy dialogue with policymakers and present the findings.“One of the things that we’ve earmarked is after the four walks that we set to take, we would engage policymakers in the policy dialogue and then get these issues to their attention,” Dr Akuaku said.That could bring discussions about air quality closer to some of the everyday decisions that shape urban life — from waste collection and disposal to transport and city planning.For the organisers, the measurements matter because advocacy is stronger when it is supported by evidence.Instead of simply telling authorities that pollution is a problem, they want to show how air quality changes from one location to another and identify the conditions contributing to those differences.Making the invisible visibleThe project is being implemented under the World Economic Forum’s Clean Air Collaborative, with support from the Global Shapers community.Ever and Better is providing the air-quality sensors used during the walks.For Dr Akuaku and his team, however, the larger ambition goes beyond four walks, a few hundred students or a few hundred newly planted trees.It is about changing how people understand the air around them.Air pollution does not always arrive with the obvious signs of environmental damage. There may be no warning when fine particles enter the lungs, no visible boundary separating clean air from polluted air and no immediate sensation telling a commuter that one street may carry a different pollution burden from another.That makes measurement important.And it explains why the project begins with something as ordinary as walking.Across Accra, the routes people take every day can become a map of the air they breathe — while the trees planted along the way offer a reminder that the response to pollution cannot stop at measuring the problem.The challenge now is whether the data gathered on those routes can translate into action in the places where decisions about Ghana’s air are made.