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Half of land in Great Britain is < 216 m from a road & >70% may be exposed to road pollution. 
Our new study asks whether we fully appreciate the extent that roads impact the environment.
A thread (1/n)
https://doi.org/10.1016/j.scitotenv.2021.145589
@KevinJGaston @JMBecologist @UniofExeterESI
Our new study asks whether we fully appreciate the extent that roads impact the environment.
A thread (1/n)
https://doi.org/10.1016/j.scitotenv.2021.145589
@KevinJGaston @JMBecologist @UniofExeterESI
Roads form vast networks across the globe with an estimated length of 64 million km. This is massive - about 1,600 times around the Earth.
But they are such an integral and normal part of our lives that it is easy to forget that this is unusual.
But they are such an integral and normal part of our lives that it is easy to forget that this is unusual.
Roads can cause diverse negative impacts for people, nature and the environment - e.g. pollution, habitat fragmentation & roadkill.
And these impacts spill out far beyond the roads themselves (e.g. up to >1 km away). https://science.sciencemag.org/content/354/6318/1423.abstract
And these impacts spill out far beyond the roads themselves (e.g. up to >1 km away). https://science.sciencemag.org/content/354/6318/1423.abstract
Previous work has modelled particular forms of road pollution (often noise and air pollution due to their effects on human health).
But we wanted to create a more complete understanding of the spatial distribution of the diverse forms of road pollution and impacts.
But we wanted to create a more complete understanding of the spatial distribution of the diverse forms of road pollution and impacts.
We modelled road pollution across Great Britain using road maps + simple models covering diverse road pollutants. We parameterised these models using data from the literature for noise, light, metals & air pollutants.
So what did we find?
So what did we find?
First, half of land is < 216 m from a road, and only 12% of land is > 1 km from a road - a rather sobering statistic!
Most roads are small, minor/local access roads, but may still contribute significantly to pollution and other impacts.
Most roads are small, minor/local access roads, but may still contribute significantly to pollution and other impacts.
Next we modelled the spatial distributions of metals and air pollutants.
As you can see, metals in soils tend to be very localised. Air pollutants on the other hand are frequently transported 100's of meters so can be very widespread.
As you can see, metals in soils tend to be very localised. Air pollutants on the other hand are frequently transported 100's of meters so can be very widespread.
Then we modelled light and noise.
On average, high light and noise levels are fairly localised. BUT most land infrequently experiences light/noise levels that may trigger ecological effects. This infrequency may make adaptation difficult. But research into this is really needed.
On average, high light and noise levels are fairly localised. BUT most land infrequently experiences light/noise levels that may trigger ecological effects. This infrequency may make adaptation difficult. But research into this is really needed.
Unfortunately, data are lacking for most pollutants & we had to make assumptions to fill gaps even for those mentioned above.
So we generalised our findings to show how the characteristics of a form of pollution affects it's spatial distribution.
So we generalised our findings to show how the characteristics of a form of pollution affects it's spatial distribution.
Lots to interpret here. But essentially, any pollutant dispersing > 250 m is likely to be very widespread.
See the paper for a full dissection.
See the paper for a full dissection.
Overall, we found that high levels of road pollution are relatively localised.
BUT, low levels of road pollution extend across at least 70% of land & potentially < 6% of land escapes road pressures.
Yet we have very little idea of the consequences of this for the environment.
BUT, low levels of road pollution extend across at least 70% of land & potentially < 6% of land escapes road pressures.
Yet we have very little idea of the consequences of this for the environment.
Two recent examples are useful to highlight this point.
This fantastic study by @sophiacooke shows that the abundance of many bird species are predicted by road exposure, with a mean effect extending 700 m from roads. https://www.nature.com/articles/s41467-020-16899-x
This fantastic study by @sophiacooke shows that the abundance of many bird species are predicted by road exposure, with a mean effect extending 700 m from roads. https://www.nature.com/articles/s41467-020-16899-x
Another very sobering study found that roads are likely a major contributor to microplastic pollution in remote regions because particles from tires and brakes are transported via the atmosphere. https://www.nature.com/articles/s41467-020-17201-9
This really makes me wonder... are we sure that roads aren't a major contributor to other environmental problems. Insect declines, for example?
We propose that a major research effort is needed, especially to understand the impacts of widespread, low levels of road pollution on the health of both people and nature.
This is especially important given that roads are rapidly changing...
E.g. the global road network is predicted to expand by 60% by 2050.
Adoption of electric vehicles will reduce some, but not all forms of road pollution. Many impacts will remain & new ones will arise.
E.g. the global road network is predicted to expand by 60% by 2050.
Adoption of electric vehicles will reduce some, but not all forms of road pollution. Many impacts will remain & new ones will arise.
Thanks for reading. This was a flying overview, but please do read the paper for more information.
https://doi.org/10.1016/j.scitotenv.2021.145589
A huge thanks goes to @KevinJGaston @JMBecologist & Juliet Osborne for patiently working with me on this one. A huge learning curve!
https://doi.org/10.1016/j.scitotenv.2021.145589
A huge thanks goes to @KevinJGaston @JMBecologist & Juliet Osborne for patiently working with me on this one. A huge learning curve!
