PM2.5 and PM10 Monitoring on Construction: A Complete Guide
You’ve heard about PM2.5 and PM10, seen them mentioned in air quality reports, and know construction sites must monitor them. But what exactly are these particles? Why do they matter separately? And how should you be measuring them on your site?
Understanding the difference between PM2.5 and PM10 is critical to managing construction air quality effectively. They have different sources, different health impacts, different regulatory limits, and different control requirements. Treating them as a single “dust problem” will leave you missing risks that regulators and environmental agencies specifically care about.
Here’s what you need to know about particulate monitoring and why source identification changes how you manage both.
What PM2.5 and PM10 Are, and Why Both Matter
PM stands for particulate matter. The number indicates the particle size in microns (millionths of a metre). PM10 includes all particles 10 microns and smaller. PM2.5 includes the finer subset—particles 2.5 microns and smaller. Think of it like a net: PM10 catches everything small enough to matter for air quality. PM2.5 catches the smallest, most dangerous particles within that net.
Size matters because it determines where particles lodge in the human respiratory system. PM10 particles are large enough that your nose and upper airways filter some of them. PM2.5 particles are so small they bypass your nose and travel deep into your lungs, where they deposit in the alveoli (air sacs) and cause direct damage. PM2.5 is therefore considered the more serious health hazard.
UK Environmental Quality Standards (EQS) set legal limits: PM10 at 50 µg/m³ as a daily mean (not to be exceeded more than 35 days per year) and 40 µg/m³ as an annual mean. PM2.5 at 25 µg/m³ as an annual mean. Construction sites must avoid breaching these limits, particularly at sensitive receptors (homes, schools, hospitals).
Construction activities generate both. Demolition, excavation, and hauling generate larger particles (PM10 range). Crushing, grinding, and traffic on unpaved roads generate finer particles (PM2.5 range). Dust suppression methods affect them differently—water controls larger particles effectively but is less effective on fine particles that stay airborne longer.
Why Particle-Only Monitoring Misses Critical Insights
Many construction sites monitor PM10 and PM2.5 levels at property boundaries—measuring compliance with EQS limits. This approach answers one question: “Are we within regulatory limits?” But it doesn’t answer the operational questions that actually prevent problems:
Which activity generated the PM2.5? Crushing creates different particulate signatures than traffic. Demolition differs from excavation. Without source identification, you can’t target controls effectively. You might increase water suppression across the entire site when the actual problem is uncontrolled crushing in one area. You deploy expensive blanket controls instead of targeted ones.
Where is the PM2.5 coming from spatially? A single boundary monitor shows you a reading but not the source direction or distance. Is the spike from your site or from wind-blown dust from neighbouring activity? You can’t defend your compliance record without knowing whether exceedances originate from your operations or external sources.
How quickly can you respond? By the time PM2.5 readings spike at a boundary sensor, fine particles have already travelled significant distances. They originated elsewhere on your site minutes earlier. Without knowing the source location, you can’t deploy targeted mitigation before particles reach sensitive receptors. You can only document that exceedances occurred.
Particle monitoring alone tells you “what happened”—levels exceeded limits. Source identification tells you “what caused it”—activity X in location Y generated it—enabling you to prevent it.
How Source Identification Transforms Particulate Management
EMSOL’s approach adds source attribution to particulate monitoring. You measure PM2.5 and PM10 levels at multiple site locations with real-time sensors, positioned to detect spatial distribution patterns. Video monitoring and AI activity detection identify which equipment is operating. Statistical correlation links measured spikes to specific activities.
The system learns that your crusher generates PM2.5 spikes within 8-12 minutes downwind of operation. Your excavator generates larger particles (PM10) but less fine dust. Your haul road generates mixed particulates depending on traffic volume and surface condition.
When a PM2.5 spike occurs at a boundary sensor, the system immediately identifies which source activity is most likely responsible, based on historical correlation. It shows video from that timeframe. Site managers can deploy targeted suppression (enclosing the crusher, wetting the haul road, or suspending excavation) instead of guessing.
This operational intelligence reduces both particles: coarser PM10 by targeting the primary source, and finer PM2.5 by understanding which activities generate respirable dust and controlling them more aggressively.
Source attribution for particulate management enables sites to move from compliance monitoring to operational control, ensuring PM2.5 and PM10 remain below regulatory limits through targeted mitigation rather than reactive documentation.
Evaluating Your Particulate Monitoring Approach
Use this checklist to assess whether your current PM monitoring supports compliance and operational control:
1. Do you measure both PM10 and PM2.5 separately? Some monitors report only PM10. You need both to understand health impacts and source characteristics.
2. Is measurement real-time or delayed? Real-time enables rapid response. Delayed measurement only supports retrospective documentation.
3. Do you monitor multiple site locations or only boundaries? Boundary monitoring alone shows exceedances. Site-internal monitoring shows where dust originates, enabling targeted control.
4. Can you correlate particulate spikes with specific activities? Without activity data, you’re guessing at sources. With it, you can prove which activity caused which spike.
5. Can your monitoring distinguish site-generated from external dust? Wind-blown dust from neighbouring sites can breach your EQS limits. If your monitoring can’t prove the dust came from elsewhere, you’re responsible. Spatial networks and directional analysis clarify this.
6. Do you have documentation that satisfies regulators? Can you show authorities: spike detected, source identified, mitigation deployed, spike controlled? Or just spike detected and spike normalised eventually?
FAQ: Particulate Monitoring Questions
Q: Why are PM2.5 levels harder to control than PM10?
A: Fine particles stay airborne longer and travel farther than larger particles. Water suppression works well for PM10 (wet particles fall quickly). PM2.5 particles bypass water droplets and remain suspended. They require source enclosure (crushing equipment), air extraction (power tools), or equipment substitution (low-dust methods). Identifying which activity generates PM2.5 is essential to deploying the right control.
Q: Do we need continuous PM2.5 monitoring or just daily measurements?
A: Continuous real-time monitoring enables rapid response and prevents exceedances. Daily or periodic sampling only documents that problems occurred. For active construction sites, continuous monitoring is more effective.
Q: How does wind speed affect PM2.5 monitoring?
A: Wind disperses particles. Low wind means particles concentrate near the source. High wind disperses them across wider areas but can also re-entrain settled dust. Monitoring networks account for wind patterns by deploying sensors upwind and downwind to detect dispersion paths.
Q: Can we meet PM2.5 limits just through dust suppression, or do we need equipment changes?
A: It depends on your specific sources. If crushing is your primary PM2.5 source, suppression alone may be insufficient—equipment enclosure or substitution is more effective. If excavation is generating fine particles, suppression is effective. Source identification reveals which control strategy will actually work for your specific operations.
Q: How do we prove to regulators that PM2.5 exceedances came from neighbouring activity, not ours?
A: Spatial monitoring networks and directional analysis show where spikes originated. Video evidence shows which of your activities (if any) were operating during the spike. Wind direction data indicates whether particles travelled from your site or from elsewhere. This combination provides credible evidence of external sources.
Next Steps
Understanding PM2.5 and PM10 separately is the foundation for effective construction air quality management. They require different monitoring approaches and different control strategies.
The next step is evaluating your current particulate monitoring against the criteria above. Does it enable source identification and targeted control? Or does it only document compliance after problems occur?
If your current approach doesn’t support proactive particulate management, contact EMSOL to assess particulate monitoring strategies that enable operational control and regulatory confidence.