Monday, April 16, 2012

Assessing Air Quality near Major Roads in Ontario, Canada

Environmental Guide for Assessing and Mitigating the Air Quality Impacts and Greenhouse Gas Emissions of Provincial Transportation Projects (78 page pdf, Environmental Policy Office, Ontario Ministry of Transportation, Jan. 2012)

Also discussed here: Air Quality and Greenhouse Gas Impacts of Transportation (Dianne Saxe, Envirolaw, Mar. 1, 2012)

Although it is considered still a “draft”, the guide reviewed today for assessing air quality and greenhouse gas emissions near roads in the province of Ontario is a major step forward. It defines when roadside vehicle emissions need to be dealt with and what standards or models should be applied. It is clear that many of the criteria take into account health impacts, such as the flagging of transportation projects where residences, schools, day cares, etc are located within 100-500 m of major roads and highways.
Key Quotes:

“MTO, as a proponent of provincial transportation initiatives, is responsible for addressing the air quality and climate change/greenhouse gas (CC/GHG) emission impacts of proposed transportation projects.. The majority of MTO’s transportation planning and design projects are subject to the Ontario and Canadian Environmental Assessment Acts. They involve new facilities or improvements to existing facilities”

“MTO provides MOE with supporting documentation so as to satisfy MOE that there is:
  1. a relatively small increase in the number of emission sources (i.e., vehicles and/ or traffic capacity); and
  2. sufficient distance from the edge of the highway right-of-way to sensitive receptors (e.g., residential dwellings and institutional buildings).
“For the preferred alternative and the planning timeframe (typically, 20 years): Assess local air quality impacts and, specifically, the likelihood, extent and duration of exceeding provincial ambient air quality criteria and national air quality standards.….The word ‘local’ refers to the immediate vicinity of the transportation system where the concentration of transportation-related air pollutants may exceed the ambient air quality criteria for one or more hours in a typical year”

For major roads, the collective experience of the scientific community suggests that the affected immediate vicinity is limited to the area within approximately 500 m of the road

 “The Guide uses a critical path methodology, focussed on whether the NOx or PM2.5 or greenhouse gas emissions of the proposed project would > 0.1% of provincial total..”

Road traffic on a typical 16 km (10 mile) portion of a four-lane highway produces more than, but not much more than, 0.1% of Ontario’s NOx and PM2.5 emissions. Hence, a 0.1% “screen” will capture any transportation alternative with emissions exceeding those of a 16 km (10 mile), four-lane highway.”

“During planning, the project team may have the opportunity to keep the distance of the highway or other major transportation facilities from sensitive receptors (residences) and critical receptors (hospitals, retirement homes, childcare centres, etc.), at approximately 100 m or greater”

“PM2.5 concentrations may exceed the 24-hour CWS of 30 g/m3 on a number of days in a typical year when highly unfavourable meteorological conditions persist. Exceedances are, however, limited to PM2.5 and PM10 and to locations within 100 m from the edge of highways”

“At very short range (30 m or less), large highway traffic volumes (over 100,000 vehicles per day) can contribute typically 80% of the ambient PM2.5 concentrations. This fraction drops to approximately 50% at 100 m from the edge of the highway”

Road pricing through electronic tolling or other means may result in a net reduction of total vehicle kilometres travelled and emissions generated in the region. The potential of this measure will, in part, depend on the availability of alternatives to the corridor and can be estimated with transportation demand models. Note: This measure is only applicable to new highways”
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