Given that air quality is poor in Croydon a cut of 17% in particulates could be very valuable.
Wildlife Gradening Forum January 2022
Holly hedges help humans in ‘street canyons’
Concern is rapidly building about the health impacts of particulate pollution in cities. While oil-fuelled vehicle use is at last declining, we need to act swiftly to reduce the problem. A team from the Global Centre for Clean Air Research at Surrey University has tested the possibility that hedges may offer protection in ‘street canyons’ – where roads and pavements run between tall walls of housing and other buildings. They set up sensors in front of and behind a thick holly hedge in a busy road, and at different heights above ground.
Changes in concentrations behind the hedge were measured with reference to the corresponding sampling point in front of the hedge for all sets of measurements. The hedge caused considerable reduction (16-17%) in particle concentrations between 1 and 1.7 m height of the PM1, PM2.5 and PM10 particles. PM10 particles are less than ten microns in diameter, and PM1 less than 1 micron. All these are small enough to be deeply inhaled, where they can pass through into the blood stream and cause many physiological problems. Clearly green infrastructure can make useful contributions to polluted streets, and the work should be extended to see the impact of other sorts of hedge – such as privet, since holly hedges are not very common.
Wildlife Gradening Forum January 2022
Holly hedges help humans in ‘street canyons’
Concern is rapidly building about the health impacts of particulate pollution in cities. While oil-fuelled vehicle use is at last declining, we need to act swiftly to reduce the problem. A team from the Global Centre for Clean Air Research at Surrey University has tested the possibility that hedges may offer protection in ‘street canyons’ – where roads and pavements run between tall walls of housing and other buildings. They set up sensors in front of and behind a thick holly hedge in a busy road, and at different heights above ground.
Changes in concentrations behind the hedge were measured with reference to the corresponding sampling point in front of the hedge for all sets of measurements. The hedge caused considerable reduction (16-17%) in particle concentrations between 1 and 1.7 m height of the PM1, PM2.5 and PM10 particles. PM10 particles are less than ten microns in diameter, and PM1 less than 1 micron. All these are small enough to be deeply inhaled, where they can pass through into the blood stream and cause many physiological problems. Clearly green infrastructure can make useful contributions to polluted streets, and the work should be extended to see the impact of other sorts of hedge – such as privet, since holly hedges are not very common.