1. Direct NO2 Emissions & Their Influence on Measured Ambient NO2: The US Situation
EU Workshop on Impact of Direct Emissions of NO2 From Road Vehicles on NO2 Concentrations
Brussels 19 September 2006
Michael P. Walsh

2. PM2.5 and Ozone Are The Most Serious Air Pollution Problems Across the US
Currently No
NO2 Nonattainment
Areas in US

5. Health effects of PM and NO2:
PM10, PM2.5
evidence of effects independent of other pollutants
NO2:
Difficult to distinguish direct impacts from those of correlated pollutants
Motor vehicles
Other sources
NOx
NO2
O3, PAN,
other oxidants
PM (via HNO3)
Increased risk of adverse health outcomes

6. NO2 ambient levels are highly correlated with PM2.5
Estimated annual means based on 2 week measurements and calibrated by routimne monitoring in ca 40 locations; TRAPCA study R2
Stockholm:
Munich:
Netherlands: 0.80
Lewne, Sc Total Environ 2004

7. Future Size of U.S. LDD Market?
Ricardo predicts US light duty diesel market to grow from 43,000 units in 2004 to 1.5 million in 2015.
Similarly, J.D. Power and Associates predicts 4X growth in the U.S. diesel car market by 2015.

8. EPA Funded Diesel Retrofit Projects

11. Addressing NO2 in Retrofit Applications
USEPA – no provision yet but watching
CARB – As of January 1, 2007, no more than a 20% increase over the baseline

12. Conclusions The US Differs From Europe Today in Two Important Respects
US has no short term NO2 ambient standard or guideline
US has almost no diesel cars and even less equipped with DPFs
But This is Changing
US Diesel Car Population, all equipped with DPFs is expected to grow rapidly
DPF Retrofits of Urban buses & Other Vehicles also expected to grow
California Increasingly Concerned With Short Term NO2 Air Quality But Not As Much As WHO
California Addressing NO2 From Retrofitted Vehicles