Tuesday, December 1, 2015

Is Exposure to Short-term Roadside Emissions a Greater Health Risk for Children?

Nitrogen dioxide, a large contributor to the p...
Nitrogen dioxide, a large contributor to the production of smog (Photo credit: Wikipedia)
Greater nitrogen dioxide concentrations at child versus adult breathing heights close to urban main road kerbside (7 page pf, Hannah S. Kenagy, Chun Lin, Hao Wu & Mathew R. Heal, Air Qual Atmos Health, Sep. 3, 2015)

Roadside emissions have been shown to pose a health threat for people living or travelling close to the roads but the studies have been restricted to measuring the exposure several metres above ground rather than at the same level as the exhaust itself or for people breathing in the pollution at different heights. Today we review research into this question with a focus on how this may pose a greater threat for children either walking or in a stroller/buggie at lower heights than their accompanying adults. Results indicate that NO2 concentration levels are 5 to 15% higher closer to the ground within 1.2 m of the side of the road or curb- with other actors such as windspeed kept constant. This has health implications for children near roads with heavy traffic (above 12,000 vehicles per day which is typical for a 2 lane busy urban road) and might suggest a greater setback for sidewalks for example.

Key Quotes: 

“The focus of this study was on possible differences in NO2 concentrations between adult and child heights as a function of different distances from heavily trafficked roads in urban areas” 

“Short-term variations in NO2 have been linked to increased hospitalisations, respiratory symptoms, and mortality, while long-term exposure to NO2 has also been associated with both morbidity and mortality” 

 “Measurements by passive diffusion tubes at differing distances from main roads in Edinburgh, UK, have shown NO 2 concentrations at 0.8 m above the ground to be significantly greater than NO2 concentration at 2.0 m above the ground, for distances up to at least 1.2 m from the kerbside of heavily trafficked (annual average daily traffic counts >12,000) urban roads. “ 

“Concentrations at the lower height were 5 – 15 % or a few micrograms per cubic metre greater, on average at the lower height than at the higher height.” 

“These observations clearly have potential public health implications as they show that children walking, or in buggies, close to busy roads can be exposed to NO2 concentrations several percent (or a few μgm−3) greater than adults at the same locations”

No comments:

Post a Comment