Continuous ambient particulate monitors a review of current technologies
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Continuous Ambient Particulate Monitors A Review of Current Technologies. by Michael Corvese, Product Manager Thermo Electron Corporation Air Quality Instruments. Aerosol Monitoring. Aerosol Characteristics Health effects Regulatory Background Sampling & Analysis Regulatory Developments.

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Continuous ambient particulate monitors a review of current technologies

Continuous Ambient Particulate MonitorsA Review of Current Technologies

by

Michael Corvese, Product Manager

Thermo Electron Corporation

Air Quality Instruments


Aerosol monitoring

Aerosol Monitoring

  • Aerosol Characteristics

  • Health effects

  • Regulatory Background

  • Sampling & Analysis

  • Regulatory Developments


Aerosol characteristics

Aerosol Characteristics

DEFINITION

Aerosol – small solid or liquid particles suspended in gas

  • Dust from nature, wind, human activity (pollen, road dust fly ash)

  • Fog from heating/cooling (clouds and fog)

  • Mist from atomization and nebulizer (sulfuric acid mist)

  • Spray from ultrasonics (insecticide spray)

  • Smoke from combustion or flame (cigarette, soot, diesel)

  • Smog from photochemicals (Urban Smog)


Aerosol characteristics1

Aerosol Characteristics

• Physical characteristics

Size distribution

Shape

Refractive Index

Concentration (mass or number)

• Chemical characteristics

Composition (chemical or elemental)

Acidity/alkalinity

• Temporal characteristics

Chemical and physical characteristics changing with time

• Spatial characteristics

Characteristics changing with location


Physical characteristics

Physical Characteristics

SIZE, SHAPE, and REFRACTIVE INDEX

  • 0.002-100µm aerosol research;

  • 0.1-100µm common sampling (0.1-10 mm)

  • Size:

  • Shape:

  • Refractive Index:

  • Many irregular shapes;

  • aerodynamic diameter emphasized

  • Wide range;

  • most consistent below 2.5mm


Physical characteristics1

Physical Characteristics

PM10

(10 mm)

PM2.5

(2.5 mm)

Hair cross section (60 mm)

Human Hair

(60 mm diameter)


Chemical characteristics

Chemical Characteristics


Health effects

Health Effects

  • Health effects are significant

  • Body of evidence is substantial


Health effects1

Health Effects

Increased hospital admissions and emergency room visits during high PM conditions

  • Aggravated asthma

  • Chronic bronchitis

  • Increase in respiratory symptoms

  • Decreased lung function

  • Premature death


Health effects2

Health Effects


Regulatory background

Regulatory Background

  • 1971—Promulgation of National Ambient Air Quality Standards (NAAQS) for SO2, NO2, O3, CO, and total suspended particulates (TSP)

  • 1978—Promulgation of particulate Pb standard

  • 1987—Promulgation of PM10 standard

  • 1997—Promulgation of revised PM10 standard and

    introduction of PM2.5 standard (also a revision of

    the O3 standard)


Regulatory background1

Regulatory Background

U.S. National Ambient Air Quality Standards (NAAQS)


Sampling and analysis

Sampling and Analysis

  • High volume methods: TSP, PM10, PM2.5, Air Toxics Sampler (PUF)

  • Low volume methods: (PM10, PM2.5, PMCoarse)

Common Gravimetric Ambient Aerosol Sampling Techniques

(Gross - Tare) / Air Volume = mg/m3


Sampling and analysis1

Sampling and Analysis

High Volume Methods: TSP and PM10 Samplers


Sampling and analysis2

Sampling and Analysis

Low Volume Methods

PM10/PM2.5 FRM & PMc/PM2.5 Dichotomous Sampler


Sampling and analysis3

Sampling and Analysis

Common Gravimetric Ambient Aerosol Sampling Techniques

(Gross - Tare) / Air Volume = mg/m3

  • Advantages: Recognized reference method, low capital cost

  • Disadvantages: Limited time resolution (typically 24-hr), long turnaround times, labor intensive, and gravimetric lab maintenance/cost


Sampling and analysis4

Sampling and Analysis

Common Continuous Ambient Aerosol Sampling Techniques

(Dm / Dt) / (DV / Dt) = mg/m3

  • Light Scattering, Absorption, and Extinction

  • Tapered Element Oscillating Microbalance

  • Beta (Electron) Attenuation

  • Hybrid Methods


Sampling and analysis5

Sampling and Analysis

Impaction Separation

Cyclone Separation

Cut Point

100%

Eficiency

50%

0%

PM100

PM1.0

PM10


Sampling and analysis6

Sampling and Analysis

  • Advantages: Low operational cost, better time resolution, increased statistical database, instantaneous turnaround (index reporting, increased knowledge of air shed characteristics)

  • Disadvantages: 2-3x capital cost, limited reference capabilities (pending USEPA & CASAC Guidelines)

Common Continuous Ambient Aerosol Sampling Techniques

(Dm / Dt) / (DV / Dt) = mg/m3


Sampling and analysis7

Sampling and Analysis


Sampling and analysis8

Sampling and Analysis

Continuous Methods

  • Light Scattering: Excellent time resolution; limited by refractive index and aerosol distribution (particle size)

  • Oscillation Frequency Measurement: Good time resolution, seasonal & regional performance issues

  • Beta (Electron) Attenuation: Proven technology, minimal performance issues, versatile


Sampling and analysis9

Sampling and Analysis


Sampling and analysis10

Advantages

Continuous method

Highly time resolved

High resolution

Disadvantages

Temperature dependency

Affected by vibration

Manual filter changes necessary

Seasonal and regional dependencies

Complex systems require some skill

Volatile losses

Sampling and Analysis

Other Technologies

Oscillation Frequency Measurement


Series fh 62 c14 features and benefits

Series FH 62 C14Features and Benefits

Mean NH

NO

-Loss l

due to heated suction tube

4

3

m

10%

0%

-10%

m

l

-20%

-30%

t

t

=

* exp(E / k

T)

0

B

t

t

l

=

/t * (1 - exp(-t/

)) - 1

-40%

m

-50%

10

20

30

40

50

60

70

80

J

in °C

Fixed heating w/auto filter changes

is an improvement over long term heating on fixed spot.

Heating Considerations

Actual and mean VOC

loss (l and l

) due to

m

heated sample area at 50°C

0%

m

-20%

) loss l and l

-40%

3

NO

-60%

4

l

m

VOC(NH

-80%

l

-100%

0

5

10

15

20

25

30

t in days


B attenuation principle of operation

b AttenuationPrinciple of Operation

  • Constant flow of aerosol is metered and sampled onto a filter stain area.

  • The detection of Beta Attenuation is proportional to increased mass.

  • Every 1-24 hrs a new filter area is zeroed and introduced.


Sharp monitor principle of operation

SHARP MonitorPrinciple of Operation

  • Combination nephelometer + beta attenuation

  • High sensitivity light scattering photometer is continuously calibrated by an integral time averaged beta attenuation mass sensor

  • Measured mass concentration remains independent of changes in the particle population being sampled


Sampling and analysis11

Sampling and Analysis

b Attenuation Technology

  • Ambient inlet

  • Sensing volume

  • b Source & detector

Direct b Attenuation

  • Advantage

  • Truly continuous

  • Non-intrusive

  • Disadvantage

  • No known manufacturers

  • Poor detection limit

  • Requires very high concentrations


Sampling and analysis12

Sampling and Analysis

b Attenuation Technology

  • Ambient Inlet

  • Sensing Volume

  • β Source & detector

  • Filter tape

Stepwise b Attenuation

  • Advantage

  • Semi-continuous

  • Sound technology

  • Good hourly precision

  • Disadvantage

  • Semi-continuous


Sampling and analysis13

Sampling and Analysis

b Attenuation Technology

  • Ambient inlet

  • Sensing volume

  • b Source & detector

  • Filter tape

Continuous β-Attenuation

  • Advantage

  • Continuous

  • Sound technology

  • Significant loading for post-collection analysis

  • Disadvantage

  • Potential extended sample loss


Sampling and analysis14

Sampling and Analysis

Hybrid Technology

  • Ambient inlet

  • Sensing volume

  • b Source, detector, nephelometer

  • Filter tape

Continuous SHARP Monitor

  • Advantage

  • Truly continuous

  • Low detection limits

  • High time resolution

  • Intelligent moisture control

  • Disadvantage

  • None


B attenuation principle of operation1

b Attenuation Principle of Operation


B attenuation

b Attenuation

Refined Mass Measurement via Dual Detector


B attenuation1

b Attenuation

Refined Mass Measurement via Dual Detector

  • A dual (a.k.a. proportional) detector allows the daughter nuclides of Radon gas to be measured and accounted for as a mass refining step.

  • This allows the C14 BETA to be consistently stable at lower ambient concentrations.

  • Important for PM2.5


Continuous particulate monitors applications

Continuous Particulate MonitorsApplications

  • NAAQS Monitoring

  • AQ Index Reporting

  • Fenceline Monitoring

  • Clean-up Sites

Ambient

In R&D …

  • Unrivaled short-term detection limits/timeresolution


Continuous particulate monitors applications1

Continuous Particulate MonitorsApplications


Regulatory developments

Regulatory Developments

  • 1997—promulgation of PM2.5 and revision of PM10

  • 1998—PM2.5 standard challenged in court

  • 1999—US Court of Appeals remanded PM2.5

    standard back to EPA for revision

  • 2001—US Supreme Court decision

    - EPA has the right to promulgate a PM2.5 standard

    - Compliance costs should not be considered

    - PM Coarse should replace PM10

  • 2005- Proposed revision of PM2.5 expected

  • 2006-Final PM2.5 and proposed PM Coarse regulation expected


Continuous particulate monitors

Continuous Particulate Monitors

The End

Thank you for your time and attention


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