Visualizing indoor ozone exposures via o-dianisidine based colorimetric passive sampler

Area of Science:

• Environmental Science
• Analytical Chemistry
• Occupational Health

Background:

• Ozone (O3) is a significant indoor air pollutant with potential health risks.
• Existing passive ozone monitoring methods have limitations in accuracy and ease of use.
• Accurate assessment of personal ozone exposure is crucial for health risk evaluation.

Purpose of the Study:

• To develop and validate a novel colorimetric ozone passive sampler (OPS) for monitoring average ozone exposure.
• To optimize the OPS for time-weighted average (TWA) measurements.
• To enhance the usability and accessibility of ozone exposure monitoring.

Main Methods:

• Incorporation of o-dianisidine dye into a polydimethylsiloxane sheet for ozone detection.
• Exposure of OPS to varying ozone concentrations (0-200 ppb) for optimization.
• Quantification of reacted o-dianisidine and analysis of colorimetric changes using image analysis (effective absorbance of blue scale, EA_B).
• Validation of OPS performance based on six key parameters including detection limits, reproducibility, and selectivity.
• Development of coloration exposure guidelines and a smartphone application for quantitative exposure assessment.

Main Results:

• The developed OPS demonstrated a visible color change upon reaction with ozone.
• Effective absorbance of the blue scale (EA_B) showed a strong correlation with ozone exposure (R² = 0.997).
• OPS validation confirmed its reliability in terms of detection limits, quantification, reproducibility, sampling rate, selectivity, and sensitivity.
• Field tests revealed significant differences between ambient ozone concentrations and personal ozone exposures.
• The smartphone app enabled accurate quantification of average ozone exposures.

Conclusions:

• The colorimetric ozone passive sampler (OPS) provides an improved method for recognizing average ozone exposure.
• The OPS, coupled with a smartphone app, offers a user-friendly tool for monitoring personal ozone exposure and raising awareness.
• This technology is valuable for assessing health risks associated with indoor ozone exposure, particularly for workers and occupants.