Date of Award

January 2026

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Krystal J. Godri Pollitt

Second Advisor

Tristan M. Nicholson

Abstract

Female reproductive health has been extensively studied in relation to airborne environmental chemical exposures, yet the impact of such exposures on male reproductive health remains comparatively underexplored. Further, studies that have investigated environmental impacts on male reproductive health have relied on generalized outdoor air quality measurements as proxies for personal exposure. This study aimed to address these gaps by using remote biospecimen collection paired with personalized exposure monitoring to characterize air pollution exposures among reproductive-aged males in the greater Seattle area and examine associations with semen parameters. Eighteen men were recruited, enrolled, and provided home-based personal air quality sensors from July through October 2025. Participants provided two semen samples, one at baseline (n = 18) and one coinciding with a wildfire smoke event (n = 15), and a subset (n = 9) additionally wore personal passive air samplers for one week prior to each semen collection. Median outdoor fine particulate matter less than 2.5 microns (PM2.5) mass concentration was 2.95 µg/m³ and median indoor PM2.5 mass concentration was 2.85 µg/m³. Indoor PM2.5 mass concentration was significantly more variable, with both environments showing measurable elevations during the Bear Gulch wildfire smoke event. Thirty-nine compounds were detected across the wearable passive samplers, including phthalates, polycyclic aromatic hydrocarbons (PAHs), flame retardants, legacy pesticides, and musks. Di-n-butyl phthalate, diisobutyl phthalate, and galaxolide were each significantly associated with decreases in sperm concentration and total motile count; Δ-9-THC was associated with decreased sperm concentration; 4,4'-DDE was associated with decreased total motile count; and fluorene and indoor PM2.5 mass concentration were associated with decreased normal morphology. These findings suggest that specific airborne chemical exposures, including indoor PM2.5 and several ubiquitous compounds, are associated with decreases in semen parameters among reproductive-aged males, and that personalized exposure assessment is necessary to capture the full breadth of these associations.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 09/16/2027

Download

Share

COinS