# Presentation: 462287

## Lessions Learned about  Mobile-Source Air Toxics (MSATs) at 3 Schools Next to U.S. 95 in Las Vegas, NV

- Prepared by:
- Paul T. Roberts, Michael C. McCarthy,
- and Steve G. Brown
- Sonoma Technology, Inc.
- Petaluma, CA
- Presented at:
- 2008 National Air Quality Conference
-  Marriott Downtown Waterfront
- Portland, OR
- April 6-9, 2008

- 906034.14-3298

- This work is funded by the Nevada Department of Transportation (NDOT); John Terry is the
- NDOT Project Manager. Joanne Spaulding & Jane Feldman (Sierra Club), Pat Mohn (NDOT),
- and Rich Baldauf (EPA) contributed to the design of this study.  Joey Landreneau and
- David Vaughn (STI) performed the monitoring and sampling.  AMS data by CSU.

## Outline 

- Introduction to US95 MSAT Study
- Monitoring sites at schools and parameters measured
- Typical characteristics of CO, NO/NOx, and black carbon (BC) at these sites
- Example efficiency of BC removal by HVAC system
- Example of characteristics of VOC and carbonyl concentrations (near, far, inside, outside)
- Example of AMS data
- Preliminary summary of MSAT characteristics
- Mitigation lessons learned, so far
- Next steps in US95 MSAT Study

## US95 Settlement Agreement 

- Court Settlement Agreement between Sierra Club and NDOT/FHWA regarding urban freeway expansion where three schools are adjacent to roadway
- Required components of settlement
- MSAT monitoring study at schools (this study)
- Filtration added to HVAC systems at schools
- Bus retrofit program
- Bus idling education
- FHWA gradient study (with EPA)

## Introduction to US95 MSAT Study

- MSAT Study Objectives:
- Characterize outdoor and indoor concentrations at schools (student exposure)
- Determine US95 vehicle contributions (before and after new lanes opened)
- Determine MSAT removal efficiencies of new filtration systems
- Focus on priority MSATs: diesel particulate matter, benzene, 1,3-butadiene, acrolein, formaldehyde, and acetaldehyde

## Introduction to US95 MSAT Study

**Routine Network (May 2007-May 2008):**
- Semi-continuous black carbon (Aethelometer) (10 sites)
- CO (3 sites)
- NO/NOx and pPAH (PAS2000) (1 site)
- Nephelometer (4 sites)
- Meteorological parameters (4 sites)
**Intensive Measurements (May/June 2007, January 2008)**
- 2-hr VOC and carbonyl samples (10 sites)
- 1-hr Sunset OC and EC
**Special January 5-28, 2008 Intensive:**
- 24-hr, 2 to12-hr Hi-vol filters for organic species & markers
- Aerodyne Aerosol Mass Spec (AMS) for organics, sulfate, and nitrate (4-min data)

## Monitoring Sites at Schools

## Fyfe Elementary School Monitoring Sites

**Legend:**     Air Inlet     Classroom      Ambient

- Ambient is 20 meters from sound wall (SW); Air inlet is 76 meters from SW.

## Western HS Monitoring Sites

**Legend:**     Air Inlet     Classroom      Ambient

- Ambient is 136 meters from sound wall (SW); Air inlet is 317 meters from SW.

## Adcock Elementary School Monitoring Sites

**Legend:**     Air Inlet     Classroom      Ambient

- Ambient is 17 meters from sound wall (SW); Air inlet was 39 meters from SW;
- air inlet for new system is 33 meters from SW.

## Fyfe Trailer and Shelter Next to Classroom (before HVAC changes)

- 20 meters from Sound Wall

- 76 meters from Sound Wall

## School Characteristics

| School | Year built | Type of Hallway | HVAC system | Filter rating |
| --- | --- | --- | --- | --- |
| Adcock ES | 2004 | Interior | Central | MERV 11 |
| Fyfe ES | Circa 1985 | Exterior | Separate units | MERV 14 |
| Western HS | 2006 | Interior | Central | MERV 11 |

## Distances (meters) from Sites to Roadway

| School | Ambient to SW | Ambient to CL | Air Inlet to SW | Air Inlet to CL |
| --- | --- | --- | --- | --- |
| Adcock ES | 17 |  60 | 39 (old)
33 (new) | 80 (old)
75 (new) |
| Fyfe ES | 20 |  60 | 76 | 120 |
| Western HS | 136 |  170 | 317 | 350 |

- Sound wall (SW); Center line (CL)

## Typical Time-Series of Concentrations at Fyfe In Winter(BC, CO, NO, OC, EC profiles are similar)

## Indoor & Air Inlet BC Concentrations at Fyfe Classroom Showing about 66% Removal (before HVAC changes)

## Example BC Time-Series Showing Classroom Being Filled with Rush-hour Pollution by HVAC(Before HVAC Changes)

## Example BC Time-Series Showing Low BC Concentrations in Fyfe Classroom, except when door left open by the teacher (after HVAC changes)

## General Characteristics of VOC and Carbonyl Concentrations

- Compare concentrations at air inlets with those nearer the roadway (“ambient” or “play field”)
- Compare concentrations at air inlets with indoor classroom concentrations
- Preliminary results for summer/before lanes expanded (winter/after lab & data analysis incomplete)
- Pollutants were split into groups
- Hydrocarbons: 1,3-butadiene, benzene, carbon tetrachloride, 2,2,4-trimethylpentane, m-&p-xylene, and toluene
- Carbonyls: acrolein, acetaldehyde, formaldehyde

## Outdoor comparison of hydrocarbons

- Concentrations at Adcock were about the same at the two sites.
- Concentrations at Fyfe were higher at the air inlet for xylenes and toluene.
- No Western High School samples were available that were measured simultaneously.

## Outdoor comparison of carbonyls

- Concentrations at Adcock were usually the same at the two sites.  However, some measurements of formaldehyde and acrolein were higher at the air inlet.
- Concentrations at Fyfe were about the same at both sites.
- Concentrations at Western were often much higher closer to the roadway.

## Outdoor Carbonyls Concentrations at Western often much higher closer to the roadway.

## Indoor/outdoor comparison of hydrocarbons

- Concentrations at Adcock were consistently higher inside the classroom than at the air inlet for the MSATs, but not for carbon tetrachloride  (around 0.1 μg/m3)
- Concentrations at Fyfe were lower in the classroom than at the air inlet, primarily for xylenes and toluene.
- There were fewer samples from Western; it may have higher indoor concentrations.

## Indoor VOC concentrations at Adcock (summer) higher than outdoor for all species except CCl4.

## Indoor MSAT concentrations at Fyfe higher than outdoor for much of the time

## Indoor/outdoor comparison of carbonyls

- Concentrations at Adcock were often higher indoors than at the air inlet for acetaldehyde and acrolein, but were occasionally higher at the inlet for formaldehyde.
- Concentrations at Fyfe, and at Western, were higher in the classroom for formaldehyde and acetaldehyde.

## AMS OM (ug/m3) vs wind speed (m/s) by hour of the day (at Fyfe)

- Note sharp jump in OM
- concentration below WS 2.5 m/s; consistent at all hours of the day

## When AMS OM is high, secondary/primary is low; also note other conditions during intensive (at Fyfe) 

## Preliminary Summary of MSAT Characteristics (1 of 2)

- Fresh pollutants go up and down together.
- Morning concentrations dominate indoor and outdoor exposure (summer); overnight and morning dominate in the winter.
- Expected pollutant gradients not always evident.
- Low wind speeds often allow high pollutant concentrations on both sides of roadway (with sound wall).

## Preliminary Summary of Characteristics (2 of 2)

- Modest BC removal with existing HVAC system in older building.
- Significant BC removal with new HVAC with filtration (late summer).
- Indoor concentrations are often higher for formaldehyde and acetaldehyde, even in older buildings (before filtration added).

## Mitigation Lessons Learned, So Far (1 of 2)

- Typical HVAC operation will fill classroom with polluted air early in the morning which can result in higher concentrations indoors in mid-to-late morning.
- Leaving classroom doors open to outdoor hall can defeat filtration system.
- Adding filtration system significantly reduces indoor concentrations (of BC; incomplete data for VOC and carbonyls).

## Mitigation Lessons Learned, So Far (2 of 2)

- Diurnal pattern of pollution is an important consideration for exposure and mitigation (for both classroom and outdoors).

## Analyses yet to be performed

- Compare MSAT concentrations with concentrations at upwind school (other side of US95) & at background school.
- Compare MSAT concentrations before and after new lanes opened.
- Correlate MSAT concentrations with winds, traffic counts, congestion, etc.
- Complete analysis of filtration efficiencies for BC, VOCs, and carbonyls.