Air Quality Monitoring

1、ENV 4101/5105 Elements of Air Pollution12/26/20211Aerosol & Particulate Research Labhttp:/www.statcan.ca/english/freepub/16-254-XIE/2007000/tablesgraphs/figure3-en.htm Reading: Chap 7.1 & 7.2Air Quality Monitoringq Monitoring Considerations Manual vs. automated (real-time, continuous) monito

2、ring Sampling time Federal reference method (FRM) vs. equivalent method (EM)q Monitoring of Ambient Air Pollutants SO2, NOx, CO, O3 Hydrocarbons PM10, PM2.5q Source Sampling and Monitoring Sampling train Isokinetic samplingq Quality Assurance Programs Quality Assurance Quality Controlq Air Quality M

3、onitoring Network12/26/20212Aerosol & Particulate Research LabWhats the use of ambient air quality monitoring data?Monitoring Considerations Sampling location: limited number of fixed site monitors whose locations reflect objectives of air quality monitoring program Lower limit of detection (LOD

4、): a sufficient amount of pollutant must be collected, f(sampling rate, duration) Integrated sampling vs. real-time sampling Area sampling vs. personal sampling Collection efficiency of the instrument: Low flow rate for gas-phase contaminants ( 10 m by impaction on a greased surfaceParticles 10 m co

5、llected on a quartz glass fiber filterWhat does the PM10 sampler measure? Number or mass concentration of particles? Animation PM10 Impactor12/26/202114Aerosol & Particulate Research LabDichotomous Samplerhttp:/crac.ucc.ie/images/sampler1.jpgHow can a Dichotomous sampler measure coarse (PM2.5-10

6、) and fine (PM2.5) particles?Animation Virtual ImpactorTEOM Series 1400abAmbient Particulate MonitorThermo Electron Co. Equivalent method: TEOMMeasure PM10, PM2.5, TSPTapered element oscillating microbalanceReal-time measurement of particle mass collected on a filter12/26/202115Aerosol & Particu

7、late Research LabCascade ImpactorAnimation Cascade ImpactorHow can we collect different sizes of particles using cascade impactor?Aerosol flow InClean air out12/26/202116Aerosol & Particulate Research LabSource Sampling and MonitoringStack Sampling of PM1)Probe inserted into the stack2)Temperatu

8、re sensor3)Pitot tube gas velocity and flow rate4)Two-module sampling unitIsokinetic Sampling1)Particles inertial forces2)Samples must be collected at the same rate of low as the stack gas12/26/202117Aerosol & Particulate Research LabWhats the use of source emission data?Isokinetic Sampling12/26

9、/2021Aerosol & Particulate Research Lab18Fig 8 -2, Aerosol Measurement, 2nd Edition, 2001Continuous Emission Monitoring (CEM) Certain utilities and industrial sources are required to measure stack emission continuously SO2, NO2, opacity, CO2, TRS, H2S, Hg12/26/2021Aerosol & Particulate Resea

10、rch Lab19OpacityRinglemann chart Compare plume darkness to Ringlemann chart by trained smoke readers Averages of measurements of or minute over an hour Simple, low cost, legal acceptanceAccuracy, Precision and BiasAccuracy is a combination of random (precision) & systematic (bias) errors. Which

11、of the 3 cases has the highest accuracy? Why?12/26/202120Aerosol & Particulate Research Lab 100%AAOErRelative Error:Coefficient of variation: 100%XCV Bias PrecisionCalibration Often used for adjusting bias-type errors Measured values are compared to standard reference values (for pollutant conce

12、ntration) or standard airflow measuring techniques/devices (for volume air flow) Primary vs. secondary standard for flow: traceable to the National Institute of Standards and Technology (NIST) Primary: bubble meter Secondary: wet or dry test meters calibrated by bubble meter Gas standards: traceable

13、 to a NIST reference material CO, SO2, NO2, NO: available in cylinder gas or permeation tubes O3: NIST certified O3 generator12/26/2021Aerosol & Particulate Research Lab21Quality Assurance ProgramsQuality Assurance (QA) Setting policy and overseeing management controls Planning, review of data c

14、ollection activities and data use Setting data quality objectives, assigning responsibilities, conducting reviews, and implementing corrective actionsGoal: Valid and reliable air quality monitoring dataQuality Control (QC) Technical aspects of data quality programs Implementation of specific QC proc

15、edures: calibrations, checks, replicate samples, routine self-assessment, and auditsIt is federal rule to document QA/QC efforts !12/26/202122Aerosol & Particulate Research LabAir Quality Monitoring NetworkState and Local Air Monitoring Stations (SLAMS) Highest pollutant concentrationsRepresenta

16、tive concentrations in areas of high population densityImpact of major emission sourcesRegional background concentrationsExtent of pollutant transport among populated areasWelfare-related impacts in more rural and remote areasNational Air Monitoring Stations (NAMS) Urban area, long-term air quality

17、monitoring networkAir quality comparisons and trends analysisPhotochemical Assessment Monitoring Stations (PAMS) Monitor O3 and photochemical air pollutantsClean Air Status and Trends Network (CASTNet)Primary source for rural O3 level and dry atmospheric deposition12/26/202123Aerosol & Particula

18、te Research LabNational Atmospheric Deposition Program (NADP)Assess the problem of atmospheric deposition and its effects on aquatic and terrestrial ecosystems (H+, NH4+, SO42-, NO3-, Cl-, Ca2+, Mg2+, K+, Hg)Quick Reflectionsq Monitoring Considerations Manual vs. automated (real-time, continuous) monitoring Sampling time Federal reference method (FRM) vs. equivalent method