Spatial extent of road pollution: A national analysis

Roads form vast, pervasive and growing networks across the Earth, causing negative environmental impacts that spill out into a ‘road-effect zone’. Previous research has estimated regional global extent of these zones using arbitrary distances, ignoring spatial distribution distance-dependent attenuation different forms road impact. With Great Britain as study area, we used mapping roads realistic estimates how pollution levels decay with distance to project pollution. We found 25% land was less than 79 m from road, 50% 216 75% 527 m. Roadless areas were scarce, confined almost exclusively uplands (mean elevation 391 m), only ca 12% in more 1 km <4% 2.5 roads. Using light, noise, heavy metals, NO2, particulate matter PM2.5 PM10 examples, estimate have zone influence extends >70% area. Potentially 6% escapes any impact, resulting nearly ubiquitously elevated levels. Generalising this, find that, whilst greatest are relatively localised around busiest roads, low (which may be ecologically significant) pervasive. Our findings demonstrate importance incorporating greater realism road-effect considering ubiquity issues. but likely apply other densely populated regions at present, many additional future due predicted rapid expansion network.