We use this expression to refer to an area of 300 meters on each side of Highway 20 and the 4 train rails that cut the city in the center. This distance is used worldwide to illustrate both air pollution and greenhouse gases (GHG) as well as noise pollution.
Air pollution
The following table shows, for example, the diffusion of nitrogen oxide within 300 meters on each side of the highway. Nitrogen oxide and volatile organic compounds are among of the precursor ozone contaminants, that is to say, reacting under the effect of solar radiation and heat (by photochemical reaction), they produce ozone. A large part of these precursors is attributable to transport. Among the air pollutants, ozone is particularly monitored because of its consequences on health. As for greenhouse gases (GHG), which are involved in climate change, transport is also one of the main sources.
Illustration of the dispersion of nitrogen oxide (NO2) as a function of the distance from a highway
Noise Pollution
The following diagram illustrates the spread of noise in decibels (dBA) within 300 meters on each side of a highway. WHO (2018):
” strongly recommends reducing noise levels produced by road traffic below 53 decibels (dB) Lden, as road traffic noise above this level is associated with adverse health effects.” Page xvi
