# A randomized crossover trial of portable air cleaners to reduce PM and SARS-CoV-2 exposures at home

> **NIH NIH P30** · RBHS-SCHOOL OF PUBLIC HEALTH · 2020 · $254,770

## Abstract

Abstract
Americans newly infected with SARS-CoV-2 (SC2) are directed to isolate at home with care provided by
household members. Isolation from others may be difficult to maintain for 2 weeks, especially in economically
challenged households without enough space to create a private sick room and bathroom. The CDC
recommends that at-home patients and their caregivers use makeshift facemasks for care-giver protection.
They do not address the possibility of virus spread via smaller particles that are not captured by improvised
facemasks. Accumulating evidence supports the significance of patient-generated aerosols, with and without
ambient PM, in the transmission of SC2 infection, but haven’t been subject to controlled study. U.S. PM2.5
concentrations are linked to a 15% increase in COVID-19 deaths per ?g/m3 of PM2.5, suggesting an interaction
between the two stressors. Thus, we plan to quantify SC2 in different PM fractions in home isolation rooms of
newly diagnosed individuals Moreover, a common recommendation to reduce indoor aerosol exposures is
filtration, and based on our experience we plan a crossover trial of air cleaners in home isolation rooms. We
hypothesize that portable indoor particle filters will reduce both airborne PM and associated viral particle
concentrations in the air around patients. We aim to test this hypothesis by enrolling 20 individuals from our
employee health clinics with newly diagnosed SC2 infections in a cross-over randomized trial of home air
cleaners. These will be continuously operated alternately for two consecutive 24-hour cycles, one cycle with a
HEPA filter, and the other with a sham filter. Size selective impactors in the isolation room will elucidate
particle sizes most associated with virus. Samplers will allow capture of PM2.5, PM coarse (10-2.5), and >PM10
fractions. In both the isolation room and the main living area we will collect total inhalable particles (d<100 µm)
at 10 L/min. These samples will be used in initial analyses to check if there is sufficient viral RNA in individual
impactor stages for reliable detection and quantification. Concentrations of PM and virus will be compared
between filtered and sham conditions .The greatest impact of our studies will be finding of a significant viral
concentration in the aerosol range (specifically, particles < 10 µm) documenting the potential for aerosol
exposure to SC2. Finding substantial viral content in aerosol size fractions will have additional public health
implications, as preventing person-to-person aerosol transmission is more challenging than preventing
transmission via larger droplets, the focus of almost all current prevention recommendations.

## Key facts

- **NIH application ID:** 10220182
- **Project number:** 3P30ES005022-33S1
- **Recipient organization:** RBHS-SCHOOL OF PUBLIC HEALTH
- **Principal Investigator:** HELMUT ZARBL
- **Activity code:** P30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $254,770
- **Award type:** 3
- **Project period:** 1997-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10220182

## Citation

> US National Institutes of Health, RePORTER application 10220182, A randomized crossover trial of portable air cleaners to reduce PM and SARS-CoV-2 exposures at home (3P30ES005022-33S1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10220182. Licensed CC0.

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