Ambient Air Quality Monitoring Equipment Siting Guidelines

Where Should I Locate an Alberta Air Quality Monitoring Station? If you are in charge of ambient air quality monitoring equipment, there are a lot of reasons you might be interested in this part of the Air Monitoring Directive (AMD).  Especially if you need to:

• Establish or maintain air monitoring systems with expert guidance on equipment placement, data collection and regulatory compliance,
• Gain insight into compliance requirements and guidelines,
• Find high-quality data that is crucial to public health and environmental protection,
• Stay with industry advancements and ensure precise monitoring for your professionals in environmental monitoring,
• Place ambient air quality monitoring equipment efficiently and cost-effectively to improve data collection,
• Minimize interference, ensure accurate data collection  and support environmentally friendly practices, or
• Place equipment correctly to ensure data accuracy and minimize pollution, safety and public health risks.

AMD Blueprint: Precision Air Monitoring Equipment Siting - For your air quality monitor to be legally compliant, what angle, height and distance from the nearest tree do you need? Don't waste time and money on biased data; unlock the rules for putting every air quality sensor, wind instrument and sampler.

Note: Select the right locations for monitors, samplers, wind instruments and precipitation equipment to ensure AMD-compliant air monitoring. To collect accurate, defensible data while minimizing interference and protecting public health, I explain siting requirements, approval obligations, dispersion modeling, and key distances, heights, and airflow criteria.

These questions ensure that air quality monitoring systems are effective and comply with regulations:

• What is the Air Monitoring Directive (AMD)?
• What's new with AMD amendments?
• Where's the best place to put ambient air quality monitoring equipment?
• Siting criteria for air monitoring equipment?
• What's the deal with continuous ambient air monitoring?
• What's the best place for wind instruments?
• What's the best way to position passive and intermittent samplers?
• Precipitation sampling sites?

Section 1 - Purpose of this Chapter

This document, part of Alberta's Air Monitoring Directive, lays out where ambient air quality monitoring equipment should be located and what equipment they should use.   There's a chapter called Site Selection. 

I will try to help you with this: What does the chapter mean when you're actually trying to establish a monitoring station?

Revisions to the Scientific Monitoring Equipment Rules

1.1 Purpose and Amendments

This chapter sets the requirements for selecting, siting and operating air monitoring stations, samplers and sensors under Alberta’s air quality monitoring framework.

These requirements took effect on September 23, 2015 and form part of the broader Air Monitoring Directive.

Overall, the updates streamline requirements, improve clarity and align the directive with current monitoring practices.

Key Updates

• Terminology updated (e.g., “precipitation sampler” changed to “precipitation sampling equipment”).
• Several siting criteria revised, including reducing the maximum obstruction angle from 30° to 26°.
• Passive sampler elevation-angle requirements lowered and some criteria removed.
• New section added for precipitation sampling equipment.
• Cable-burying requirements removed; electrical requirements updated to align with the Alberta Electrical Code.
• Section 3 numbering adjusted following the removal of SS 3-C.
• Installation requirements for traps and filters revised.
• Documentation requirements for continuous monitoring stations and networks clarified.
• Cross-references corrected and some mapping and sketch requirements removed.

Section 2 - Ambient Air Quality Monitoring Equipment Site Selection and Siting Criteria

Example of passive sampler siting requirements

2.1 Site Selection

Air monitoring stations, samplers and sensors must be sited in accordance with the Air Monitoring Directive. The primary goal is to place monitors where they provide meaningful data about facility emissions.

• Dispersion modelling must be used to identify suitable monitoring locations for new facilities requiring approval, unless otherwise directed by the Director.
• Final locations must comply with the detailed requirements in the Site Selection Chapter.
• Written authorization from the Director is required before installing ambient air quality monitoring equipment and reporting data from it. For industrial operations, this approval is typically incorporated into the facility approval process.

Dispersion modelling frequently identifies several locations that satisfy the AMD. Choosing among them requires professional judgement about prevailing wind patterns, nearby emission sources, terrain, accessibility and the monitoring objectives.

2.2 Standard Siting Criteria

Effective monitoring sites should be:

• Accessible year-round under normal weather conditions.
• Equipped with necessary utilities and security measures.
• Free from airflow obstructions such as trees, fences, or buildings that could bias results.

When siting sample inlets, consider:

• Inlet height and probe length.
• Distance from airflow disturbances.
• Proximity to roads and other emission sources.

Data collection at precise locations

Avoid locations affected by stack downwash, ground-level dust, or unpaved roads. Where dust sources cannot be avoided, sample inlets should be elevated or set back sufficiently to maintain appropriate measurements.

2.3 Continuous Ambient Air Monitoring Siting Criteria

Unless otherwise directed by the Director, continuous ambient air quality monitoring equipment must be sited to increase the quality of your measurements. Key requirements include:

• At least 20 m from trees.  Trees create turbulence and localized deposition that can bias measured concentrations. The AMD setback helps ensure the sampler measures the surrounding air instead of the immediate influence of vegetation.
• Unobstructed airflow from most wind directions.
• The angle between the monitor and any obstacle must not exceed 26.5°.  That angle limits the amount of airflow blocked by nearby structures so the sampler experiences actual winds.
• Minimum setbacks from roads based on average daily traffic (Table 2).
• Avoid portable generators; if used, exhaust must be at least 30 m downwind of the sampling inlet.
• Pollutant-specific sampling inlet requirements are provided in Table 1.

2.3.1 Wind Instrument Siting

Wind measurement instruments should be located to ensure better data:

• Preferably mounted 10 m above shelter height.
• The surrounding 100 m radius should be uniform and free of obstructions.
• Alternatively, instruments may be placed more than 10 obstacle heights away from obstructions.
• Wind direction should be verified using precise methods such as survey benchmarks or the Local Apparent Noon procedure (Appendix A).

Refer to AMD Table 3 and Figure 2 for detailed requirements.

2.4 Passive and Intermittent Sampler Siting Criteria Passive and intermittent samplers must be located to ensure good long-term air quality measurements.

Passive samplers (Table 4):

• Typically installed 1.5–4 m above ground.
• Must meet specified clearance and angle requirements.
• Duplicate samplers should be within 4 m of each other.

Intermittent samplers (Table 5):

• Installed 2–15 m above ground.
• Must meet setback requirements from obstacles and other samplers.
• Require unrestricted airflow from specified wind quadrants.

2.5 Precipitation Sampling Equipment Siting Criteria 

When precipitation monitoring is conducted alongside continuous gas and particulate monitoring, siting conflicts may occur. Sites should provide open exposure on three sides, with continuous analyzers located in the predominant wind direction. Additional guidance is available in AMD Chapter 4.

2.5.1 Precipitation Sampling Equipment

To ensure accurate precipitation sampling:

• Position the collector opening 1.0–3.0 m above ground.
• Install on a level surface.
• Ensure surrounding obstructions are no more than 2.5 times the collector height.
• Maintain at least 5 m from paved or concrete surfaces.
• Keep open space within 10 tree heights of nearby trees.
• Mount the inlet 1 m above expected snow accumulation.
• Orient the chassis east–west.
• Connect to a shared 15-amp power supply with the rain gauge.

See AMD Figure 4 for illustration.

2.5.2 Background Precipitation Sampling Equipment

Alberta follows CAPMoN (Canadian Air and Precipitation Monitoring Network) criteria for background precipitation sites. Requirements (Table 6) ensure monitoring locations:

• Represent regional topography, airflow and precipitation patterns.
• Avoid local pollution influences.
• Meet setback requirements from population centres, transportation routes, water bodies, pollution sources and site obstructions.

Refer to Table 6, Figure 4 and Section 2.5.1 for details.

See the Complete Chapter 3 pdf for more info and to access the complete guidelines.  

At Calvin Consulting Group Ltd - We've helped establish and evaluate air monitoring locations. In practice, that means looking beyond the minimum distance requirements to determine whether a proposed station will actually answer the monitoring question it was designed to answer.

Need to choose a monitoring location?

A compliant location isn't necessarily the best location.

Calvin Consulting can help evaluate candidate monitoring locations using:

• facility emissions
• nearby sources
• meteorology
• terrain
• land use
• dispersion modelling
• AMD siting requirements
• practical access and maintenance considerations

Need help selecting or evaluating a monitoring site? Contact Barry

Please contact Barry at...

...for more about AMD compliance.  Calvin Consulting is a leader in air quality, dedicated to advancing industry standards and providing valuable resources to enhance environmental monitoring.

Five common air-monitoring siting mistakes

1. Choosing the location before understanding the monitoring objective.

2. Treating the AMD distance requirements as the entire siting exercise.

3. Ignoring nearby sources, roads, buildings or terrain.

4. Selecting a technically compliant site that is impossible to maintain year-round.

5. Assuming the closest available location is the most representative location.

The dangerous part? A monitoring site can satisfy a checklist and still fail to address the real problem.

FOR YOUR CONVENIENCE: Before You Select a Monitoring Site

Ask yourself:

✓ What pollutant am I trying to measure?

✓ Am I measuring maximum impacts or community exposure?

✓ Is this station intended for compliance or trend monitoring?

✓ Will future construction change airflow?

✓ Can technicians safely access it year-round?

✓ Will utilities remain available?

✓ Can calibration gases be transported there?

✓ Will vegetation change over the next decade?

✓ Does the location satisfy both AMD and the monitoring objective?

Need to select a monitoring location?

→ Understand the AMD siting criteria
→ Identify potential locations
→ Use emissions/source information
→ Consider meteorology and terrain
→ Use dispersion modelling where appropriate
→ Evaluate candidate monitoring locations
→ Develop the QAP
→ Implement and audit the monitoring network

A location can satisfy the basic distance requirements and still be a poor monitoring site. We often look beyond the checklist to determine whether the station will actually measure the air quality question the network was designed to answer.

Do you have concerns about air pollution in your area??

Perhaps modelling air pollution will provide the answers to your question.

That is what I do on a full-time basis.  Find out if it is necessary for your project.

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Thank you to my research and writing assistants, and the author remains responsible for the content.

Monitoring Site Pre-Approval Checklist

Before finalizing a monitoring location, verify:

□ Monitoring objective defined
□ Relevant AMD siting criteria identified
□ Approval requirements reviewed
□ Nearby emission sources mapped
□ Dispersion modelling considered where appropriate
□ Prevailing wind conditions assessed
□ Terrain reviewed
□ Trees and buildings assessed
□ Roadway influence assessed
□ Sample inlet height confirmed
□ Obstruction angles/distances checked
□ Power available
□ Communications available
□ Security addressed
□ Year-round access confirmed
□ Snow/ice considerations addressed
□ Generator exhaust considered
□ Landowner/access permissions confirmed
□ QAP implications considered
□ Documentation /photos/site plan prepared