Sensing the invisible, breathing through the trees

This is an experimental project by concerned Milanese citizens. Engineer Roberto Re played a key role. He has measured fine particles with low-cost sensors for years.

Prof. Davide Cerati, architect and research fellow at Politecnico di Milano, leads the monitoring. His colleague, Prof. Giovanni Castaldo, a senior researcher, supports him.

The project receives support from the Municipality of Milan, AMAT, and ARPA. Milan and the Po Valley rank among Europe’s most polluted areas.

Prof. Castaldo explains pollution comes from geography and human activity. Scientific studies link air pollution to health damage. Annual healthcare costs exceed $30 billion.

Prof. Cerati adds that EU and WHO policies aim to improve air quality. However, results remain poor, especially in stagnant-climate areas with high emissions.

Castaldo says cutting emissions isn’t enough. Replacing old boilers and phasing out polluting vehicles help, but nature-based solutions are also needed.

The researchers work on urban environmental projects at ENVIREG, a lab at Politecnico. Trees and vegetation reduce city pollution effectively.

Cerati notes that leaves absorb large amounts of pollutants. They also help regulate urban climate. A mature tree can capture nearly one kilogram of fine particles yearly.

Greenery like trees, shrubs, lawns, and green roofs helps reduce pollution. Castaldo says they can model urban microclimate benefits even at block level.

Unfortunately, climate data often comes from distant stations. Milan lacks a dense sensor network for local air quality data.

The researchers joined this “citizen science” project eagerly. They see two main benefits: creating a sensor network and measuring vegetation’s effect on pollution.

Real-time data could support tools like maps showing shaded routes for vulnerable people during heatwaves.

They installed monitoring stations in two places: Via Padova, a busy street with high emissions, and Trotter Park, rich in trees and vegetation.

The collected data aims to measure air quality differences between traffic-heavy streets and green parks.

They also want to provide policymakers with clear guidance on urban redevelopment and green space planning.