1 Pollutants of Concern in North America and Europe John G. Watson Judith C. Chow Desert Research Institute, Reno, NV, USA presented at The Workshop on Air Quality Management, Measurement, Modeling, and Health Effects University of Zagreb Zagreb, Croatia May 24, 2007

2 Objectives Identify air pollutants and reasons for concern Describe different approaches to improving air quality

3 Several air pollutant categories and concerns Criteria Pollutants –indicators of air quality with maximum concentrations above which adverse effects on human health may occur (CO, SO 2, NO 2, O 3, Pb, PM [TSP, RSP, PM 10, PM 2.5 ]) Hazardous Air Pollutants (HAPs, or toxics) –emissions known or suspected to cause cancer or other serious health effects, such as reproductive effects, birth defects, or other adverse environmental effects (many VOCs, metals, PAHs, diesel particles) Acid Deposition –highly oxidizing pollutants that destroy forests, crops, lakes (H 2 SO 4, HNO 3, O 3 )

4 Several air pollutant categories and concerns Material Damage –reactive or decolorizing pollutants that destroy or soil buildings, clothing, vehicles, antiquities (SO 2, H 2 SO 4, HNO 3, O 3, soot [BC: black carbon], soil dust) Odors –unpleasant olfactory experiences (reduced sulfur compounds, certain VOCs) Mercury –included in HAPs, but also results in bioaccumulation in lakes and fish through deposition

5 Several air pollutant categories and concerns Visibility Reducing Gases and PM –PM 2.5 components, including sulfate, nitrate, ammonium, organic carbon, elemental carbon, sea salt, and soil. NO 2 absorbs light in plumes Halocarbons –deplete stratospheric O 3 (Freon-12, SF 6, halon, other fluorocarbons) Climate Forcing Gases and PM –change the Earth’s radiation balance directly by absorbing electromagnetic radiation or indirectly by changing cloud cover and water vapor (CO 2, CH 4, halocarbons, BC, ultrafine particles)

6 Same pollutants in several categories Many pollutants are in several regulatory categories (e.g., SO 2, NO x, VOCs, SO 4 =, NO 3 -, BC) Several pollutants come from similar activities (coal burning, industrial processes, vegetative burning, transportation, windblown dust) Several have similar spatial scales and lifetimes –Microscale (10 to 100 m) and Middle-scale (100 to 500 m): odors, traffic, HAPs, dustfall –Neighborhood-scale (500 m to 4 km): vehicle exhaust, residential heating and burning, primary industrial emissions –Urban-scale (4 to 100 km): O 3, secondary sulfates and nitrates –Regional-scale (100 to 1,000 km): O 3, secondary sulfates and nitrates, forest fires, regional haze –Continental-scale (1,000 to 10,000 km): large scale fires, Asian and Saharan dust –Global-scale (>10,000 km): greenhouse gases, halocarbons, BC

7 Several methods for air pollution control Ambient air quality standards Emission limits (with certification tests) Effluent treatment requirements (Reasonably Available, Best Available, Lowest Achievable Emissions Technologies) Product design specification Fuel specifications (with certification tests) Emission fees and fines Congestion pricing Forced shutdowns Emissions caps and trading Inspection and Maintenance programs Energy efficiency requirements Demonstrated reasonable progress

8 Ambient air quality standards are basis for regulation PollutantEU StdEU AvgEU ExcedUS StdUS AvgUS Exced CO10 mg/m 3 8 hr max/day 0/yr 10 mg/m 3 40 mg/m 3 8 hr 1 hr 1/yr SO µg/m µg/m 3 1 hr 24 hr 24/yr 3/yr 365 µg/m 3 80 µg/m 3 24 hr 1 yr 1010 NO µg/m 3 40 µg/m 3 1 hr 1 yr 18/yr 0/yr 100 µg/m 3 1 yr0 O3O3 120 µg/m 3 8 hr max/day 25/3-yr160 µg/m 3 8 hr max/day 4 th 3-yr avg PM µg/m 3 40 µg/m 3 24 hr 1 yr 35/yr 0/yr 150 µg/m 3 24 hr2 nd 3-yr avg PM 2.5 None 35 µg/m 3 15 µg/m 3 24 hr 3 yr 98% 0/3 yr TSP Pb0.5 µg/m 3 1 yr0/yr1.5 µg/m 3.25 yr0/quarter Benzene0.5 µg/m 3 1 yr0/yrHAPs As120 µg/m 3 1 yr0/yrHAPs Cd5 ng/m 3 1 yr0/yrHAPs Ni20 ng/m 3 1 yr0/yrHAPs PAH (BaP)1 ng/m 3 1 yr0/yrHAPs

9 Elements of an air quality standard Evidence of association with adverse health effects Indicator (e.g., O 3 for oxidants, PM 2.5 for PM) associated with (but not necessarily the only cause of) effects Averaging time(s) (some effect acute, others long term) Threshold concentration (set to protect public health with a safety margin) Form (e.g., number of exceedances allowed) Enforcement and penalties (EU has limit values and less strict target values. US has timelines for attainment and potential for sanctions)

10 Levels for adverse health differ by pollutant CO has well defined chemical character and health end-point

11 SO 2 is well defined pollutant, but with several health end-points

12 PM has multiple components and multiple health end- points The PM-mortality effect estimates are consistently larger for longer time scales of exposure.

13 Air quality progress in Europe and the US CO, SO 2, NO 2, and Pb standards are largely met in U.S. and Europe Pb no longer used as a fuel additive Most sulfur removed from diesel and gasoline fuels New industrial sources have SO 2, NO x, and PM emission controls On-road diesel engine emissions requirements Montreal Protocol on fluorocarbon releases Regional emission caps for industrial SO 2 and NO x

14 EURO passenger car emissions standards (g/km)

15 Problem: O 3 and PM 2.5 are remaining problems at local and regional levels

16 Emerging air quality issues Greenhouse gases and particles: How can these emissions be reduced along with other pollutants? How can they be regulated? Long-range transport: Emissions from China, India, Latin America, and Africa are rising and affect concentrations in Europe and the U.S. How can these emissions be controlled? Multi-pollutant control strategies and effects: Are individual pollutant regulations still adequate? Ultrafine particles: Are these the real causes of PM health effects? Unintended consequences: How to anticipate people’s reaction to pollution regulations?

17 Vehicle Exhaust, Residential Heating and Cooking Photochemical Nucleation Vehicle Exhaust Particle Diameter (nm) dN/dlogD p (number cm -3 ) Ultrafine particles come from primary emitters and form in the atmosphere

18 Saharan dust affects southern Europe

19 Conclusions Criteria pollutants (CO, SO 2, NO 2, O 3, Pb, and PM [TSP, RSP, PM 10, PM 2.5 ]) are the basis for air quality regulation, but they are not the only ones of importance Europe and US have successfully reduced exposures to CO, SO 2, NO 2, and Pb, but O 3 and PM are still of concern Remaining pollutants have regional sources and require regional strategies for reduction Emerging economies (China, India, etc) are increasing emissions, and these affect Europe and the US Greenhouse gases and particles that affect climate and ultrafine particles that affect health will become more important pollutants to be regulated in the future