Human exposure to PM10 microplastics in indoor air

Area of Science:

• Environmental Science
• Toxicology
• Public Health

Background:

• Airborne microplastics (MPs) are prevalent indoors, raising health concerns.
• Previous research focused on larger MPs (20-200 µm), less likely to reach deep lung tissues.
• The health impact of inhaling smaller, inhalable MPs (1-10 µm) remains largely unquantified.

Purpose of the Study:

• To investigate airborne, indoor suspended microplastics (MPs) in the inhalable 1-10 µm size range.
• To quantify MP concentrations in residential and car cabin environments.
• To estimate daily human inhalation exposure to indoor MPs across different size ranges.

Main Methods:

• Utilized Raman spectroscopy to analyze airborne MPs in residential and car cabin settings.
• Focused on microplastics in the 1-10 µm size range (MP1-10 µm).
• Combined new data with existing studies to establish a consensus indoor MP concentration distribution.

Main Results:

• Median indoor MP concentrations were 528 MPs/m³ (residential) and 2,238 MPs/m³ (car cabin).
• Predominant polymers were polyethylene (PE) in homes and polyamide (PA) in cars.
• 94% of MPs were smaller than 10 µm, predominantly in fragment shapes, following a power-law size distribution.

Conclusions:

• Estimated daily inhalation of indoor MPs is 3,200 MPs/day (10-300 µm) and 68,000 MPs/day (MP1-10 µm).
• MP1-10 µm inhalation estimates are 100-fold higher than previous extrapolations from larger MPs.
• The substantial inhalation of small MPs suggests potentially underestimated health risks.