Monitoring Survey in the Vicinity of St. Marys Cement: Interim Report

Similar documents
Ambient Air Sampling Program First Quarter 2016 Report Sudbury, Ontario. Submitted to:

Ambient Air Sampling Program Second Quarter 2015 Report Sudbury, Ontario. Submitted to:

Ambient Air Sampling Program First Quarter 2017 Report City of Greater Sudbury, Ontario

FRAPPÉ/DISCOVER-AQ (July/August 2014) in perspective of multi-year ozone analysis

Major Point/Area Sources Name Type Major Emissions Distance (m) Direction CFB Cold Lake Air Force Base NOx, PM, HC, TRS 3km to aircraft West

Mount Cotton Quarry Dust Investigation

Technical Memorandum. City of Salem, Stormwater Management Design Standards. Project No:

Memorandum. Air Sampling

STAFF REPORT ACTION REQUIRED

Causes of high PM 10 values measured in Denmark in 2006

Addendum to the. Submitted to U.S. EPA Region 9 March 17, Prepared by:

Wind Resource Data Summary Cotal Area, Guam Data Summary and Transmittal for December 2011

RICHARDS BAY CLEAN AIR ASSOCIATION

Appendix 2a. Radar Wind Profiler Data

Colorado Front Range Wildfires Situation Report #7 Monday, July 02, :15 AM (MDT)

MARINE VESSEL FRONTIER ANGEL & MARINE VESSEL EL CONDOR PASA

California Urban Infill Trip Generation Study. Jim Daisa, P.E.

Alberta: Air Zones Report

Development of wind rose diagrams for Kadapa region of Rayalaseema

One of the coldest places in the country - Peter Sinks yet again sets this year s coldest temperature record for the contiguous United States.

Roadway Traffic Noise Feasibility Assessment. 315 Chapel Street. Ottawa, Ontario

J17.3 Impact Assessment on Local Meteorology due to the Land Use Changes During Urban Development in Seoul

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY RE.GION BROADWAY NEW YORK, NEW YORK

1.18 EVALUATION OF THE CALINE4 AND CAR-FMI MODELS AGAINST THE DATA FROM A ROADSIDE MEASUREMENT CAMPAIGN

Air Quality in Port Alberni

Air Quality Simulation of Traffic Related Emissions: Application of Fine-Scaled Dispersion Modelling

Chapter 3. Materials and Methods

Dispersion Modeling of the Transport and Dispersion of SO 2 Pollutants Emitted from a Power Plant in Tong Liang

Traffic Impact Study

Greater Toronto Area Cordon Count Summary Analysis of Traffic Trends 1985 to 2011

The weather in Iceland 2012

Transportation Noise Assessment. 590 Rideau Street. Ottawa, Ontario

Chapter 2: The Project site & its Environment

Debbie Lee, Communications and Public Affairs Officer. Update on Southern California Edison s Capital Improvement Projects

Traffic Noise Impact Study. 383 Slater Street / 400 Albert Street. Ottawa, Ontario

Definitions Weather and Climate Climates of NYS Weather Climate 2012 Characteristics of Climate Regions of NYS NYS s Climates 1.

Monthly Report: Chevron Richmond Community Air Monitoring Program. Report Number: RCAMP_MO_11 Date: February RCAMP_MO_11 Page 1 of 26

Supplementary appendix

Using sensor data and inversion techniques to systematically reduce dispersion model error

TAKE ROLL CALL TO DETERMINE IF THERE IS A QUORUM OF MEMBERS PRESENT

DELINEATION OF A POTENTIAL GASEOUS ELEMENTAL MERCURY EMISSIONS SOURCE IN NORTHEASTERN NEW JERSEY SNJ-DEP-SR11-018

Temporal and spatial distributions of urban heat island in Nanjing. Yu Zhou

SHADOW STUDY REPORT REGARDING

Appendixx C Travel Demand Model Development and Forecasting Lubbock Outer Route Study June 2014

MAPPING THE RAINFALL EVENT FOR STORMWATER QUALITY CONTROL

AN AIR QUALITY MANAGEMENT SYSTEM FOR CYPRUS

An Online Platform for Sustainable Water Management for Ontario Sod Producers

An assessment of time changes of the health risk of PM10 based on GRIMM analyzer data and respiratory deposition model

Preliminary Conceptual Model Development

UPDATE OF REGIONAL WEATHER AND SMOKE HAZE (September 2017)

SIMMER WORKSHOP (Science, Policy & Heat-Health Decision Making) Toronto

PRELIMINARY WIND RESOURCE ASSESSMENT OF WINDYGATES FIRST NATIONS PROJECT. Department of Innovation, Energy and Mines Contact. Rick Halas Document No

High-Resolution Air Quality Modelling in the Oil Sands

Paine Field Airport Existing and Future Environmental Assessment, Initiation of Commercial Service Noise Analysis

Central Ohio Air Quality End of Season Report. 111 Liberty Street, Suite 100 Columbus, OH Mid-Ohio Regional Planning Commission

Greater Toronto Area/ Clean Air Council. Air Quality Modeling Pilot Project

UTM coordinates, x and y X Y Percent Ownership 100

Radar Analysis of Second Wave of UFO Sightings Near Stephenville, Texas. October 21 and 23, 2008

Applications. Remote Weather Station with Telephone Communications. Tripod Tower Weather Station with 4-20 ma Outputs

WIND DATA REPORT FOR THE YAKUTAT JULY 2004 APRIL 2005

QAPP AMENDMENT FORM: Amendment # 10

Project No India Basin Shadow Study San Francisco, California, USA

The Climate of Murray County

Roadway Traffic Noise Feasibility Assessment. Conservancy Subdivision. Ottawa, Ontario

JEP John E. Jack Pflum, P.E. Consulting Engineering 7541 Hosbrook Road, Cincinnati, OH Telephone:

Who is polluting the Columbia River Gorge?

FROM: Brent Auvermann, Texas A&M Department of Biological and Agricultural Engineering, 6500 Amarillo Blvd. West, Amarillo, TX

Draft Urban Hamilton Official Plan. Amendment No. XX

Wen Xu* Alberta Environment and Sustainable Resource Development, Edmonton, Alberta, Canada

Climates of NYS. Definitions. Climate Regions of NYS. Storm Tracks. Climate Controls 10/13/2011. Characteristics of NYS s Climates

SECTION 2 AMBIENT AIR MONITORING PROGRAM PLAN AMENDMENT FORM: ISSUE 18 DATE FORM SUBMITTED: 2/10/11

IV. ENVIRONMENTAL IMPACT ANALYSIS B. AESTHETICS SHADE/SHADOW

Measurement and Analysis of the Vertical Distribution Characteristic of the Atmospheric Particle Concentration in Beijing District

QAPP AMENDMENT FORM: Amendment # 18

not for commercial-scale installations. Thus, there is a need to study the effects of snow on

2016 Meteorology Summary

Life Science Archives (LSA)

Review of Anemometer Calibration Standards

PW 001 SNOW REMOVAL AND SANDING FOR ROADWAYS AND SIDEWALKS October 6, 2014 (#223-14) Original October 19, 2015; October 15, 2018 Public Works

Long-Term Trend of Summer Rainfall at Selected Stations in the Republic of Korea

Jason Bentley Ashe Prelim_Research_Notebook_Data MDS_I Fall_2007

forest fires, emission estimates, dispersion modelling, air quality, fire growth, meteorology 2.0 METHODS

THE HISTORY OF WEATHER OBSERVING IN CHEYENNE, WYOMING,

Wind Potential Evaluation in El Salvador Abstract: Key words: 1. Introduction Corresponding author:

Monthly Report: Chevron Richmond Community Air Monitoring Program. Report Number: RCAMP_MO_5 Date: August RCAMP_MO_5 Page 1 of 26

ABSTRACT 1.-INTRODUCTION

DEPARTMENT OF EARTH & CLIMATE SCIENCES Name SAN FRANCISCO STATE UNIVERSITY Nov 29, ERTH 360 Test #2 200 pts

WestConnex M4 East Project

Transportation Noise Feasibility Assessment & 3930 Riverside Drive Ottawa, Ontario

Monthly Long Range Weather Commentary Issued: SEPTEMBER 19, 2016 Steven A. Root, CCM, Chief Analytics Officer, Sr. VP,

Transportation Noise Assessment. 560 Rideau Street. Ottawa, Ontario

Intercomparison Exercise of Spatial Representativeness Methods

Role of Meteorology on Urban Air Pollution Dispersion: A 20yr Analysis for Delhi, India

Feasibility Noise Assessment. Westgate Shopping Centre Redevelopment. Ottawa, Ontario

TransCity Legacy Way Air Monitoring Network

Conceptual Model for Ozone in the Austin-Round Rock Metropolitan Statistical Area

Implementation of GIS and Remote Sensing Techniques for Air Quality Assessment. Tarek A. E. El-Damaty and Essam Ghanem

Meteorological Data Collection, X/Q and D/Q, Critical Receptors

State of the Climate in Turkey in 2014

Supplement of Non-methane hydrocarbon variability in Athens during wintertime: the role of traffic and heating

Transcription:

Technical Memorandum 2017-2018 Monitoring Survey in the Vicinity of St. Marys Cement: Interim Report Ontario Ministry of the Environment & Climate Change Report Prepared by: Terrestrial Assessment and Field Services Unit Air Monitoring and Transboundary Air Sciences Section Environmental Monitoring and Reporting Branch Report Completion Date: January 2018

Survey Background At the request of the Ministry of the Environment and Climate Change s (MOECC or Ministry) London District Office, the Environmental Monitoring and Reporting Branch (EMRB) initiated an air monitoring survey of in the vicinity of St. Marys Cement, located at 585 Water Street South, St. Marys, Ontario, starting on July 5, 2017. The objective of this survey is to measure concentrations of sulphur dioxide (SO 2 ), particulate matter (PM) and nitrogen oxides (NO X ) in ambient air in the vicinity of St. Marys Cement over a period of at least one year. This interim report summarizes the first three months of data collected. Summary of Activities One monitoring site, using a temporary compact air monitoring station (Airpointer), was established for use in this survey. The air monitoring station was installed at the St. Marys Fire Department, which is located north east of the facility in a residential area of St. Marys (See Appendix A, Figure 1). The Airpointer was installed on July 5, 2017 with collection of valid realtime data starting on July 11, 2017. The air monitoring station is outfitted with sulphur dioxide (SO 2 ), nitrogen oxides (NO X ) and particulate matter air monitoring instrumentation along with an anemometer for local wind measurements. The monitoring site was established in an area of the community that has voiced concern about the potential impacts of emissions from St. Marys Cement and is predominantly in a downwind position from the facility based on local wind patterns. Comparison to Benchmarks Sulphur Dioxide (SO 2 ) Sulphur dioxide measurements are taken on a real-time, 1-minute average basis. Concentrations measured between July 11, 2017 and October 11, 2017 have been compared to applicable air quality standards found under Ontario Regulation 419/05 Local Air Quality (O. Reg. 419/05) and Ontario s Ambient Air Quality Criteria (AAQCs). No exceedances of the air quality standards or AAQCs were measured at the station over the initial three month period. A summary of these measurements and the comparison to the air quality standards and AAQCs can be found in Table 1 and Table 6, Appendix B. For informational purposes, sulphur dioxide measurements were also compared to the proposed, updated SO 2 air quality standards and AAQCs, currently posted on the Environmental Registry for public comment. No levels were measured above the proposed standards and AAQCs. A summary of this comparison can be found in Table 2, Appendix B. Nitrogen Oxides (NO X ) Nitrogen oxides measurements are taken on a real-time, 1-minute average basis. Concentrations measured between July 11, 2017 and October 11, 2017 have been compared to applicable O. Reg. 419/05 air quality standards and AAQCs. No exceedances of the standards or AAQCs were measured at the station during the initial three month period. A summary of these measurements and comparison data can be found in Tables 3 and 6, Appendix B.

Particulate Monitoring (PM 2.5 /PM 10 ) Particulate measurements are taken on a real-time, 1-minute average basis. Between July 11, 2017 and August 23, 2017 the particulate monitoring instrument was outfitted with a PM 2.5 size selective inlet which measures particulate matter with an aerodynamic diameter of less than 2.5 µm. After August 24, 2017, the size selective inlet was changed to PM 10 that allows particles of less than 10 µm in aerodynamic diameter to be measured. Concentrations have been compared to applicable AAQCs. No exceedances of the AAQCs were measured at the station for PM 2.5 between July 11, 2017 and August 23, 2017. No exceedances of the AAQCs were measured at the station for PM 10 between August 24, 2017 and October 11, 2017. A summary of these measurements and comparison data can be found in Tables 4, 5 and 6 of Appendix B. Source Identification Meteorological parameters are measured concurrently with the sulphur dioxide (SO 2 ), nitrogen oxides (NO X ) and particulate (PM 2.5 /PM 10 ) measurements to assist in determining the potential source of emissions. The meteorological sensor is integrated with the Airpointer air monitoring station using a 2.5 m high tower. This height conforms to acceptable sighting requirements for tripod-mounted or temporary wind sensors (Operations Manual for Air Quality Monitoring in Ontario, PIBS 6687e); however these types of sensors are more subject to influence from surrounding topography and can thus be more representative of a microclimate. There was good correlation however with regional wind direction when the measurements were compared to other permanent meteorological towers in the area. Wind speed data collected by the Airpointer air monitoring station however were lower than measurements collected by the permanent regional meteorological towers indicating significant influence from the surrounding topography. To visually assess potential emission sources, pollution roses have been created from the 1-hour average meteorological and pollutant data using valid data from July 11, 2017 to October 11, 2017. Pollution roses are a graphical representation of how pollutant concentration and wind direction are distributed at a particular location over a specified period of time. The data are plotted using a polar coordinate system. The spokes of the pollution rose indicate the direction from which the wind is coming and are divided into five degree increments. The length of the spoke shows the frequency of a particular wind direction expressed as a percentage of time as indicated by the horizontal axis scale. Each spoke is further divided into colour coded bands that indicate pollutant concentration ranges measured and their frequency. Sulphur Dioxide (SO 2 ) The pollution rose for sulphur dioxide shows that, for the majority of time, concentrations were 5, indicated by the turquoise colour in the spokes (Appendix A, Figure 2). At times concentrations were measured between 5 and 10 (green) for all wind directions other than the north and northwest. During a small percentage of time concentrations were measured between 10 and 25 (purple) and up to 25 to 50 (navy blue), but generally only when winds were from the southwest. Although no exceedances of the applicable standards or AAQC for sulphur dioxide were reported, areas in the vicinity of the air monitoring station occasionally

experienced SO 2 levels above typical background levels when winds were from the southwest, coming from the direction of St. Marys Cement. The average SO 2 concentrations are similar to the average ambient SO 2 measurements collected by the MOECC s Windsor Downtown Air Quality Health Index (AQHI) air quality monitoring station for the same time period (Table 6, Appendix B). The Ministry s AQHI air monitoring stations have been located in cities across Ontario to determine the current state of ambient air quality within those communities. The St. Marys temporary air station measured an average SO 2 concentration of 2.4 while the average SO 2 concentration measured by the Ministry s Windsor AQHI air monitoring station was 2.2. The Windsor station, while indicative of general ambient air in Windsor, does show some influence from nearby heavy industry (e.g. Zug Island) and vehicular traffic on the Ambassador Bridge. The St. Marys station average SO 2 concentration was about half the measured value of the average SO 2 concentration measured at the Ministry s Hamilton Mountain AQHI air monitoring station (5.3 ) over the same time period. The Hamilton AQHI station, located away from the industrial area of the city, is still influenced by local sources including iron and steel making facilities which are known sources of SO 2. St. Marys Cement s Emission Summary and Dispersion Modelling (ESDM) report confirms that the facility is an emitter of SO 2. This suggests that St. Marys Cement is a likely source of SO 2 in the area surrounding the Ministry s temporary air monitoring station. Nitrogen Oxides (NO X ) The NO X pollution rose (Appendix A, Figure 3) shows that measured concentrations fell within three concentration ranges for all wind directions; 5 (turquoise), 5-10 (green) and 10-50 (purple). On a few occasions, concentrations were measured between 50 and 100 (navy blue) when winds were from the southwest. The pollution rose indicates that multiple sources of NO X are being measured at the temporary air monitoring station. St. Marys Cement s ESDM report confirms that the facility emits NO X, however many sources in urban and industrial environments generate NO X. While no exceedances of the applicable O. Reg. 419/05 air quality standards or AAQCs were measured, areas in the vicinity of the air monitoring station experienced levels higher than background from all directions. A higher percentage of the 10-50 concentrations (purple) were measured when winds were from the southwest, the direction of St. Marys Cement, with the lowest percentage being measured during west winds. The average NO X concentration measured at St. Marys (6.6 ) was similar to levels measured at the Ministry s AQHI stations located in nearby cities: London (8.1 ) and Brantford (6.4 ), and lower than stations that are influenced by heavy industry and/or significant contributions from vehicular traffic. The Ministry s Hamilton Mountain AQHI air monitoring station measured an average NO X concentration of 12.8 while the Ministry s Windsor Downtown AQHI station measured an average NO X concentration of 17.9. Other potential sources of NO X exist between St. Marys Cement and the Ministry s temporary air monitoring station including some industrial facilities located on James St. S. and vehicular traffic. St. Marys Cement is likely a contributing source of NO X in the vicinity of the air monitoring station.

Particulate Monitoring (PM 2.5 /PM 10 ) St. Marys Cement s ESDM report states that they are an emitter of total suspended particulate. This confirms that they generate particulate matter, but specifics about particle size distribution are not given. Total suspended particulate (TSP) matter is typically measured with non-continuous measurement technology, averaged over a 24-hour period, whereas PM 10 and PM 2.5 are often measured in real-time. Real-time particulate matter measurements of PM 10 and PM 2.5 were chosen for this survey over TSP since they are more relevant for this type of community monitoring. Larger particulate matter (>10 µm) tends to settle out of the air quickly, is not transported large distances, and is less likely to travel into the community. Additionally, source identification and potential health impacts are more easily assessed with real-time PM 10 and PM 2.5 measurements. The PM 2.5 pollution rose shows that between July 11, 2017 and August 23, 2017 there was no discernable difference in concentration levels measured at the station with varying wind direction (Appendix A, Figure 4). In addition, PM 2.5 measured at Ministry AQHI air monitoring stations in other communities showed similar concentrations over the same time period; the average PM 2.5 concentration measured at St. Marys was 7.7 versus 7.1 in London, 7.8 in Brantford, 7.2 at Hamilton Mountain, and 7.9 at Windsor Downtown. This indicates that PM 2.5 measured at the St. Marys station was dominated by regional area background levels. The PM 10 pollution rose shows that there were modest differences in concentration levels measured at the temporary St Mary s air monitoring station with wind direction between August 24, 2017 and October 11, 2017 (Appendix A, Figure 5). The average PM 10 concentration of during this time period was 14.1. Measured concentrations fell within in three concentration ranges for all wind directions; 5 (turquoise), 5-15 (green) and 15-30 (purple). Additionally, when winds were coming from the northeast, southwest, east and southeast, concentrations were measured in the 30 to 50 concentration range (navy blue) with occasional measurements between 50 and 100 (yellow). The largest percentage of concentrations measured in the 30 to 50 range (navy blue) occurred when winds were from the northeast. The pollution rose suggests that PM 10 was being measured from multiple sources from various wind directions. While no exceedances of the province s AAQC were measured, areas in the vicinity of the temporary air monitoring station experienced levels higher than background from multiple directions. A higher percentage of the 30-50 concentrations (navy blue) were measured when winds were from the northeast, with some contributions coming from the direction of St. Marys Cement (southwest). The lowest concentrations were measured during northwest winds. Summary of Findings Results from the Ministry s temporary air monitoring station established in St. Marys, Ontario by the MOECC have been presented and discussed in this interim report for the time period of July 11, 2017 to October 11, 2017.

Monitoring results were compared to the existing applicable O. Reg. 419/07 air quality standards and AAQCs for all parameters and to the newly proposed air quality standards and AAQCs for SO 2. No exceedances of the air quality standards or the AAQCs were measured at the monitoring station for the time period referenced. Additionally, no levels were measured above the newly proposed air quality standards and AAQCs for SO 2 currently posted on the Environmental Registry for public review and comment. While pollutant levels did not exceed any provincial air quality standards or benchmarks, pollution roses did show that some measured levels were above background and that St. Marys Cement was a potential contributor to levels measured in the vicinity of the Ministry s temporary air monitoring station. St. Marys Cement is a likely source of SO 2. The pollution rose showed a discernable increase in levels when winds were coming from the direction of the facility. St. Marys Cement is a likely contributing source of NO X along with other nearby industrial facilities and urban activities including vehicular traffic. The pollution rose showed that levels were slightly elevated when winds were from southwest of the monitoring station compared to other directions. PM 2.5 measured at the St. Marys station was dominated by regional area background levels. The PM 2.5 pollution rose shows no discernable difference in concentration levels measured at the station amongst different wind directions. The air monitoring station measured PM 10 from multiple sources from various wind directions, with possible contributions from St. Marys Cement. There were slightly elevated concentrations when winds were coming from the northeast, southwest, east and the southeast, with the lowest concentrations occurring during northwest winds. In summary, St Marys Cement is a potential contributor to the concentrations of SO 2, NO x, and particulate matter measured at the Ministry s temporary air monitoring station established in St Marys for the time period referenced. The average concentrations of SO 2, NO X and PM 2.5 levels are similar to concentrations measured at other comparable Ministry AQHI ambient air monitoring stations. The area in the vicinity of the Ministry s temporary St Marys air monitoring station experienced periods of time where concentrations of these common air pollutants were above background levels. This is typical of urban areas or areas in proximity to industrial activities and/or transportation related sources. This is an interim report that summarizes and discusses the first three months of data collected as part of a survey which will last at least one complete year. Further data collection over a full year will provide a more comprehensive dataset that will facilitate a more representative assessment of the air quality at the site including potential seasonal variations and fluctuations in emissions from contributing sources.

Appendix A: Maps and Pollution Roses Figure 1: Temporary Air Monitoring Station St. Marys Ontario, July 11 to October 11, 2017

Figure 2: Pollution Rose for SO 2, St. Marys Ontario, July 11 to October 11, 2017

Figure 3: Pollution Rose for NO X, St. Marys Ontario, July 11 to October 11, 2017

Figure 4: Pollution Rose for PM 2.5, St. Marys Ontario, July 11 to August 23, 2017

Figure 5: Pollution Rose for PM 10, St. Marys Ontario, July 11 to August 23, 2017

Appendix B: Summary Tables Table 1: Exceedances of Current O. Reg. 419/05 Standards and AAQCs for SO 2, St. Marys Ontario, July 11 to October 11, 2017 Standard/AAQC Exceedance Details O. Reg. 419/05 Schedule 3 AAQC Averaging period Value Total Exceedances Date Time Downwind of St. Marys Cement? X X 1-hour 690 0 - - - X X 24-hour 275 0 - - - X annual 55 N/A - - - Table 2: Measured Concentrations Above the Proposed O. Reg. 419/05 Standards and AAQCs for SO 2, St. Marys Ontario, July 11 to October 11, 2017 Proposed Standard/AAQC Excursion Details O. Reg. 419/05 Schedule 3 O. Reg. 419/05 URT AAQC Averaging period Value Total # of excursions above benchmark Date Time Downwind of St. Marys Cement? X 10-min 180 0 - - - X X 1-hour 100 0 - - - X X annual 10 N/A - - - X 1-hour 690 0 - - - X ½-hour 830 0 - - - Table 3: Exceedances of the O. Reg. 419/05 Standards and AAQCs for NO X, St. Marys Ontario, July 11 to October 11, 2017 Standard/AAQC Exceedance Details O. Reg. 419/05 Schedule 3 AAQC Averaging period Value Total Exceedances Date Time Downwind of St. Marys Cement? X X 1-hour 400 0 - - - X X 24-hour 200 0 - - -

Table 4: Exceedances of the AAQC for PM 2.5 July 11, 2017 to August 23, 2017, St. Marys Ontario AAQC Exceedance Details Averaging period Value Total Exceedances Date Time Downwind of St. Marys Cement? 24-hour 30 0 - - - Table 5: Exceedances of the AAQC for PM 10 August 24, 2017 to October 11, 2017, St. Marys Ontario AAQC Exceedance Details Averaging period Value Total Exceedances Date Time Downwind of St. Marys Cement? 24-hour 50 0 - - - Table 6: Average Pollutant Concentrations July 11 to October 11, 2017 at select AQHI stations and St. Marys Air Monitoring Station NO X SO 2 PM 2.5 PM 10 St. Marys Air Monitoring 6.6 2.4 7.7 14.1 Station London AQHI Station 8.1 nm 7.1 nm Brantford AQHI Station 6.4 nm 7.8 nm Hamilton Mountain AQHI 12.8 5.3 7.2 nm Station Windsor Downtown AQHI 17.9 2.2 7.9 nm Station nm = not measured measurements taken from July 11 to August 23, 2017. measurements taken from August 24 to October 11, 2017. Conversions from ppb to were calculated using T = 10 o C, P = 1atm.