Assessing Personal PM2.5 Exposure and Respiratory Virus Infections among Farmworkers in the Southeastern United States

Abstract

BACKGROUND AND AIM: Occupational studies have identified exposure to particulate matter (PM) air pollution as an emerging concern among crop farmworkers, with previous data suggesting that harvesting tasks contribute to the highest occupational PM exposures among this population. Particulates from agricultural dust may be composed of multi-pollutant mixtures of pesticides, heavy metals, mineral silicas, and microbes. Moreover, chronic respiratory conditions, as well as mortality attributable to acute respiratory infections, are notably elevated among crop farmworkers. In the United States, this workforce is comprised primarily of migrant and immigrant populations that face a multitude of social inequities. METHODS: Our pilot study uses personal air samplers to assess occupational exposure to respirable agricultural dust (PM2.5) among a hard-to-reach and vulnerable population of mostly Mexican-American farmworkers harvesting crops in the southeastern US. Participants worked in fernery harvesting, nursery greenhouses, and strawberry harvesting. We conduct prospective, weekly follow-up of participants during influenza season to determine the incidence of acute respiratory symptoms and viral respiratory infections. RESULTS:We collected nasal swab biospecimens from symptomatic participants and tested these samples for SARS-Cov-2 and 20 different respiratory pathogens using a panel array (Biofire). Thus far, we have collected n=30 occupational PM2.5 exposure samples. A majority of occupational PM2.5 exposure levels were above the US EPA limit for annual PM2.5 concentration, with four participants exposed above the OSHA PEL. Of the participants that enrolled in weekly follow-ups (n=20), four participants reported acute respiratory symptoms. Molecular analysis of collected biospecimen were positive for human rhinovirus (n=2), SARS-Cov-2 (n=1), and two samples are pending laboratory analysis. CONCLUSIONS:Follow-up of participants and chemical analysis of PM2.5 filters is ongoing. To our knowledge, this is the first study to assess occupational PM2.5 exposure and incidence of respiratory infections in Southeastern US-hired farmworkers, while characterizing the chemical composition of occupational dust exposures. KEYWORDS: COVID-19, Epidemiology, Exposure assessment, Infectious diseases, Particulate matter, Occupational exposures