Also discussed here: Stopping at red lights exposes drivers to high levels of air pollution (ScienceDaily, Feb.12, 2015)
And here: Red Lights Are Air Pollution Hotspots (Jenna Iacurci, Nature World News, Feb. 21, 2015)
Today we review research into the role that traffic lights play in adding to the exposure of drivers, pedestrians and the nearby environment to toxic vehicle emissions. Results indicate that the 2% of time on the road spent idling at traffic lights contributes 25% to the exposure to particulate matter from emissions. The tendency for cars to be close together while waiting at red lights adds to the concentration of the pollution emitted and the development of urban “hot spots”. Adding to the pollution is frequent acceleration and braking that takes place along a road with signalized lights. Not directly mentioned are the benefits of using modern roundabouts to avoid these periods of pollution while idling.
Key Quotes:
“Our time spent travelling in cars has remain fairly constant during the past decade despite the efforts to reduce it and with more cars than ever joining the roads, we are being exposed to increasing levels of air pollution as we undertake our daily commutes."
“ Quantification of disproportionate contribution made by signalised traffic intersections (TIs) to overall daily commuting exposure is important but barely known.”
“Congested TIs were found to become hot–spots when vehicle accelerate from idling conditions” “drivers spend just 2% of their journey time passing through traffic intersections managed by lights, this short duration contributes to about 25% of total exposure to these harmful particles."
“With drivers decelerating and stopping at lights, then revving up to move quickly when lights go green, peak particle concentration was found to be 29 times higher than that during free flowing traffic conditions”
“As well as concentration, researchers found that as cars tend to be close together at lights, the likelihood of exposure to vehicle emissions is also significantly increased”
"Air pollution was recently placed in the top ten health risks faced by human beings globally, with the World Health Organization linking air pollution to seven million premature deaths every year”
