Research

The Zaragoza Trams Study

Authors
MONSOLAR, Benjamin Beltran Bennasar
Facility
The Zaragoza Tram System; Zargoza, Spain
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Full Report

Field Study: Plasma Air 600 Series Reduces VOCs and Virus-Sized Particles in Zaragoza Trams

Independent Real-World Evaluation Demonstrates Significant Airborne Contaminant Reduction in Public Transit Vehicles

Tranvía de Zaragoza tram car in Spain evaluated during Plasma Air 600 Series indoor air quality testing

This third-party field evaluation was performed by Benjamin Beltran Bennasar, Chemical Engineer and Senior Technician of Indoor Environmental Quality. The testing evaluated the performance of Plasma Air needlepoint bipolar ionization inside active tram cars of the Tranvía de Zaragoza fleet, serving Zaragoza—the fifth largest city in Spain.

Study Objective

The objective of this real-world evaluation was to assess the efficacy of the Plasma Air 600 Series (Model 604) in reducing airborne contaminants—specifically 54 volatile organic compounds (VOCs), seven aldehyde compounds, and fine particulate matter (PM) sizes spanning 0.3 µm to 5.0 µm (representing virus-sized bioaerosols and allergens).

Secondary monitoring was conducted for Ozone (O₃), Formaldehyde (CH₂O), and Nitrogen Dioxide (NO₂) to confirm zero secondary pollutant generation during operation.

Testing Methodology and Vehicle Specifications

Testing was conducted inside two passenger tram cars under controlled real-world baseline conditions:

  • Internal Cabin Volume: 159 m³ (5,615 ft³), excluding the driver cabins.
  • Air Handling Configuration: Two standalone ceiling fan coil units per car distributing air through ceiling ductwork into occupied areas.
  • Airflow Rates: Nominal flow rate of 2,150 m³/h (1,265 CFM) per AC unit, supplying 27 air changes per hour (ACH).
  • Filtration Baseline: Standard G3/G4 filters (MERV 5 to MERV 8 equivalence).

Reference Standards and Operational Controls

Testing followed standard UNE 171330-2:2014 (Indoor Environmental Quality Inspection Procedures) under real-world "unclean" baseline conditions:

  • Pre-Test Baseline ("Unclean Condition"): Trams were operated in normal public service for more than one full day prior to testing (exposed to passengers in street clothing with personal perfumes, deodorants, and lotions) with frequent door cycles.
  • Workshop Testing Environment: Trams were moved to the maintenance workshop without pre-ventilation or chemical cleaning.
  • Test Conditions: Zero passengers inside during active sampling; no outdoor air intake (100% recirculation); return filters removed.

Baseline control samples were taken before turning on the Plasma Air 604 units. Sequential readings were recorded every 15 minutes over a two-day testing period.

Results & Key Findings

1. 80% Reduction in Total VOC Concentrations

Following 6 hours of Plasma Air (PA604) operation, chromatographic analysis of active pump samples showed an 80% reduction in total VOC concentration across 54 target chemical compounds. All measured VOC levels remained well below the Threshold Limit Values (TLV) established by Spain’s National Institute for Occupational Health and Safety (INSST).

2. Significant Particle Clearance Across Virus-Sized Microns

After 2.5 hours of continuous PA604 operation, particle counter readings demonstrated significant aerosol clearance across all monitored micron ratings:

  • 0.3 Micron Particles (Virus-Sized Bioaerosols): 73% Reduction
  • 0.5 Micron Particles (Respirable Aerosols): 88% Reduction
  • 1.0 Micron Particles (Fine Dust / Bacteria): 86% Reduction
  • 5.0 Micron Particles (Pollen / Mold Spores): 75% Reduction

3. Zero Byproduct Generation (UL 2998 Alignment)

Active air sampling confirmed that continuous operation of Plasma Air bipolar ionizers generated zero harmful chemical byproducts:

  • Ozone (O₃): No detectable generation (below quantification limits).
  • Nitrogen Dioxide (NO₂): No detectable generation (below quantification limits).
  • Aldehydes: No detectable generation of Acetaldehyde, Acrolein, Benzaldehyde, Crotonaldehyde, Formaldehyde, Glutaraldehyde, or Propionaldehyde.

Conclusion

The third-party field evaluation confirms that Plasma Air 600 Series needlepoint bipolar ionization significantly reduces airborne VOCs and fine respirable particles in enclosed transit environments without producing ozone or toxic chemical byproducts.

Explore Plasma Air 600 Series products for public transit and commercial HVAC systems.

Sources & Study Attribution

Field study conducted by Monsolar / Tayra S.L. under the direction of Project Director Paul Gerard O’Donohoe. Chemical analysis performed by Benjamin Beltran Bennasar, Senior Technician of Indoor Environmental Quality. Testing governed under UNE 171330-2:2014 standards.