C40 Cities

The Problem

Almost all urban residents in the world are breathing air that doesn’t meet World Health Organization (WHO) guidelines for what is safe to breathe. In fact, 41% of cities have air pollution over 7 times higher than WHO’s recommendation [State of Global Air 2022]. Moreover, climate change is impacting the health and wellbeing of city residents: from deaths caused by extreme heat, to flooding, to failing infrastructure, and more.

The Solution

Cities are uniquely positioned to address the pollution that is warming our planet and polluting our air. Cities hold many of the policy levers needed to facilitate a fair and rapid transition to clean, low-carbon, people-friendly infrastructure that improves their residents’ health, quality of life, and economic opportunities.

C40 Cities was founded in 2005 to engage and support cities in this critical work. Launched by a steering committee of mayors of 18 megacities, C40 is now a global network of nearly 100 mayors united in action to confront the climate crisis and improve air quality.

How OpenAQ Helps

C40 Cities uses a wide range of data to inform communications, to make the best decisions and drive effective action, and to measure and report progress. This includes data on the OpenAQ platform, which are used to estimate citywide PM2.5 annual averages in order to compare air pollution levels before and after an action has been implemented and to measure progress over time. C40 also uses data on OpenAQ to double check the number of monitors within cities after the cities self-report.

For More Information

Learn more about C40 Cities’ air quality work .

Read our blog How Data on OpenAQ Are Being Used by C40 Cities where we interview Toby Coombes, Project Manager for Air Quality Policy and Analysis at C40, to get his perspective on the role data plays in tackling air and climate pollution and to learn how C40 uses data on the OpenAQ platform.