• Global air pollution exposure has long been based on satellite retrievals.
  • But as local measurements are implemented, we have seen that satellites tend to underestimate concentrations of fine inhalable particles.
  • Nobody can say they have clean air in the absence of public pollution measurements.

For years, global air pollution exposure estimates have been based on satellite retrievals, but as locally based measurements are implemented, we have seen that satellites tend to severely underestimate concentrations of fine inhalable particles (PM2.5).

Satellite-derived PM2.5 concentrations are estimated based on aerosol optical depth measurements. They assume aerosol vertical profiles that do not necessarily represent the strong thermal inversions that characterize polluted areas.

For example, in 2019, the University of Chicago’s satellite estimates put Chile’s concentration of fine inhalable particles at 11 micrograms per cubic meter of air (µg/m3), while the Organization for Economic Co-operation and Development’s (OECD) mean estimation, which was derived from direct measurements, was 23.7µg/m3 for the same year. This was more than double what the university estimated from satellite retrievals.

The World Health Organization (WHO) has also measured air pollution in Chile, Mexico, and Colombia. Recently, the organization updated its air pollution guidelines by reducing recommended mean values from 10µg/m3 to 5µg/m3 annual means of PM2.5. The previous guidelines were exceeded in 90% of Latin America, and the new guidelines are exceeded in virtually every city in the region.

But the measurements for vast areas in those countries are not public. And yet, these countries all have long-standing, localised efforts to reduce pollution in their capital cities and are now expanding these efforts to the smaller cities. The world’s attention and focus must shift from countries that are already measuring pollution to the many countries that do not have a single publicly available air-quality monitor.

Information is power

The Fundación Horizonte Ciudadano, a non-profit, non-partisan foundation created in 2018, and Pontificia Universidad Católica de Valparaíso, are working to connect the dots on air pollution in Chile. Their aim is to fill the large gaps in measurements through Red Aires Nuevos para la Infancia, the largest citizen network on air quality in the region. This network has already contributed to the doubling of public measurement sites.

By using low costs sensors in collaboration with IQ Air, an organization that operates the world's largest free real-time information platform on air quality, the network sends air-quality data to pre-school communities and develops plans of action to prevent exposure and raise awareness. It does this in partnership with local universities, governments, and local communities.

The network is now operational in 11 countries (Chile, Peru, Ecuador, Mexico, Colombia, Brazil, Uruguay, Argentina, Nicaragua, El Salvador, and the Dominican Republic) and in more than 50 cities.

The ambition is to provide a collaboration platform for all participants to share experiences and success stories. For example, in Coyhaique, Chile, the most polluted city in the Americas, teachers use the data to assess whether children can exercise. They have also developed a no-idling campaign for the city.

In Santiago, researchers assess the changes in exposure when electric buses operate near schools. And in Lima, the municipality provides public pollution-measurement data in low-income communities that are not covered by the official network.

What's the World Economic Forum doing about the future of cities?

Cities represent humanity's greatest achievements - and greatest challenges. From inequality to air pollution, poorly designed cities are feeling the strain as 68% of humanity is predicted to live in urban areas by 2050.

The World Economic Forum supports a number of projects designed to make cities cleaner, greener and more inclusive.

These include hosting the Global Future Council on Cities and Urbanization, which gathers bright ideas from around the world to inspire city leaders, and running the Future of Urban Development and Services initiative. The latter focuses on how themes such as the circular economy and the Fourth Industrial Revolution can be harnessed to create better cities. To shed light on the housing crisis, the Forum has produced the report Making Affordable Housing a Reality in Cities.

Protecting children

Pollution sensors are best installed in pre-schools because these schools are focal points in communities. When schools become monitoring sites members of local communities feel a sense of ownership over the monitoring process. They are much more engaged than they would with official monitoring sites, which are often far removed from the locality.

The network focuses on children because young lungs are particularly vulnerable to air pollution. Children breathe in much more air than adults in comparison to their body size. Reducing air pollution results in tangible benefits for early childhood. In Chile for example, between 2014 and 2019 a total of 14 new pollution control programmes were implemented to address nonattainment of PM2.5 standards.

As a result, mean annual concentrations fell by 49% in that period. Emergency room visits due to respiratory disease dropped by 17% in places where these programmes were in place, whereas they rose by 7% in places where they were not.

A total of 472, 000 emergency room visits were avoided between 2014 and 2019, 56% of which would have been children between 0 and 4 years old. It is hoped these results can be replicated in other cities

Next steps

Finally, we need to reflect on the opportunities the new WHO guidelines bring. It’s been 16 years since the last update. Since then, there has been global consensus on the Paris Agreement, which enables us to assess country efforts to reduce global warming. According to the agreement, countries are either aligned or misaligned to the 1.5 °C-degree target. There is no such assessment for air quality.

We need to learn from the climate community wherein you are either aligned with the WHO guidelines as a country, or you are not. Countries that have committed to net-zero emissions by 2050 have done so to protect their children’s future. On the flipside, no country in the Americas has committed to the WHO guidelines on air quality. As a result, children are dying of preventable pollution-related deaths today. Not in 2050. Today. Think about it.