---
title: "Particulate matter (PM)"
description: "Particulate matter (PM) is airborne solid or liquid particulate. PM is categorised by aerodynamic diameter:"
canonical_url: "https://sylio.co/glossary/particulate-matter"
last_updated: "2026-06-28T02:29:34.743Z"
---

**Particulate matter (PM)** is airborne solid or liquid particulate. PM is categorised by aerodynamic diameter:

<table>
<thead>
  <tr>
    <th>
      Category
    </th>
    
    <th>
      Diameter
    </th>
    
    <th>
      Health and capture significance
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      PM₁₀
    </td>
    
    <td>
      < 10 µm
    </td>
    
    <td>
      Inhalable; permit-limited; captured by <a href="/glossary/electrostatic-precipitator">
        ESP
      </a>
      
       and <a href="/glossary/baghouse">
        baghouse
      </a>
    </td>
  </tr>
  
  <tr>
    <td>
      PM₂.₅
    </td>
    
    <td>
      < 2.5 µm
    </td>
    
    <td>
      Respirable; tighter permit limits; demands high-efficiency control
    </td>
  </tr>
  
  <tr>
    <td>
      PM₁
    </td>
    
    <td>
      < 1 µm
    </td>
    
    <td>
      Reaches deep lung; most health-significant; hardest to capture
    </td>
  </tr>
</tbody>
</table>

## Smaller PM is harder to capture

ESPs and baghouses both capture larger particulate more easily than smaller. PM₁ capture demands either [PTFE-membrane bags](/glossary/ptfe-membrane-filter-bag) (baghouse) or carefully-tuned ESP fields with adequate [SCA](/glossary/specific-collection-area). Fouling that degrades either system has its first visible impact on fine PM penetration.

## Sonic horns and PM control

[Sonic horns](/glossary/sonic-horn) preserve ESP and baghouse collection efficiency across the operating cycle by preventing the dust-layer thickening or [bag blinding](/glossary/bag-blinding) that would otherwise compromise fine-PM capture.

## Related terms

- [Opacity](/glossary/opacity)
- [Electrostatic precipitator](/glossary/electrostatic-precipitator)
- [Baghouse](/glossary/baghouse)
- [Mass loading](/glossary/mass-loading)