Reactive oxygen species on indoor surfaces

Area of Science:

• Environmental Chemistry
• Indoor Air Quality
• Oxidative Stress

Background:

• Reactive oxygen species (ROS) are unstable molecules found in indoor aerosols.
• The indoor origin of aerosolized ROS remains largely unquantified.
• Indoor surface films are hypothesized as a primary source of indoor aerosol ROS.

Purpose of the Study:

• To quantify reactive oxygen species (ROS) concentrations on indoor surfaces.
• To investigate the influence of surface contact and orientation on ROS levels.
• To simulate and analyze the formation of ROS from surface lipid oxidation.

Main Methods:

• Xylenol orange ferrous oxidation assay used to measure ROS on extracted surface films.
• ROS concentrations measured on frequently and infrequently touched residential surfaces.
• Laboratory simulation involving dosing glass plates with a surface lipid mixture (SLM) and exposing them to air.

Main Results:

• Frequently touched surfaces showed ROS concentrations >0.2 nmol cm^-2.
• Horizontally oriented plates accumulated higher ROS concentrations than vertical plates, with a maximum of 1.3 nmol cm^-2 near an electric stove.
• Laboratory simulations demonstrated a rapid increase in ROS on SLM-coated plates within the first 5-6 days, reaching 5-6 nmol cm^-2, followed by a slow decrease.

Conclusions:

• Indoor surfaces, particularly those frequently touched and horizontally oriented, are a significant source of reactive oxygen species (ROS).
• Surface lipid oxidation is a key mechanism for ROS generation on indoor surfaces.
• These findings support the hypothesis that indoor surfaces contribute substantially to the ROS burden in indoor environments.