Speciating volatile organic compounds in indoor air: using GC to interpret real-time PTR-MS signals.

Proton transfer reaction mass spectrometry (PTR-MS) is often employed to characterize gas-phase compounds in both indoor and outdoor environments. PTR-MS measurements are usually made without upstream chromatographic separation, so it can be challenging to differentiate between an ion of interest, its isomers, and fragmentation products from other species all detected at the same mass-to-charge ratio. These isomeric contributions and fragmentation interferences can confound the determination of accurate compound mixing ratios, the assignment of accurate chemical properties, and corresponding analyses of chemical fate.

Jingle bells, what are those smells? Indoor VOC emissions from a live Christmas tree.

Every year in the United States conifers are purchased to serve as Christmas trees in homes where they emit volatile organic compounds (VOCs) to the indoor environment. Although many studies have measured the ecosystem-level emissions of VOCs from conifers outdoors (characterizing monoterpene, isoprene, and aldehyde emissions), little is known about VOC emission rates once a conifer is brought indoors. Using a proton transfer reaction-mass spectrometer we characterized the VOCs emitted from a freshly cut Douglas Fir for 17 days in an environmentally controlled chamber.

Dynamics of residential indoor gas- and particle-phase water-soluble organic carbon: measurements during the CASA experiment.

Previous time-integrated (2 h to 4 h) measurements show that total gas-phase water-soluble organic carbon (WSOC) is 10 to 20 times higher inside homes compared to outside. However, concentration dynamics of WSOC and total particle phase WSOC (WSOC)-are not well understood. During the Chemical Assessment of Surfaces and Air (CASA) experiment, we measured concentration dynamics of WSOC and WSOC inside a residential test facility in the house background and during scripted activities.

The chemical assessment of surfaces and air (CASA) study: using chemical and physical perturbations in a test house to investigate indoor processes.

The Chemical Assessment of Surfaces and Air (CASA) study aimed to understand how chemicals transform in the indoor environment using perturbations (, cooking, cleaning) or additions of indoor and outdoor pollutants in a well-controlled test house. Chemical additions ranged from individual compounds (, gaseous ammonia or ozone) to more complex mixtures (, a wildfire smoke proxy and a commercial pesticide). Physical perturbations included varying temperature, ventilation rates, and relative humidity.

Ozone generation and chemistry from 222 nm germicidal ultraviolet light in a fragrant restroom.

Devices using 222 nm germicidal ultraviolet light (GUV222) have been marketed to reduce virus transmission indoors with low risk of occupant harm from direct UV exposure. GUV222 generates ozone, an indoor air pollutant and oxidant, under constrained laboratory conditions, but the chemistry byproducts of GUV222-generated ozone in real indoor spaces is uncharacterized. We deployed GUV222 in a public restroom, with an air change rate of 1 h one weekend and 2 h the next, to measure ozone formation and byproducts generated from ozone chemistry indoors.

Quantification of Byproduct Formation from Portable Air Cleaners Using a Proposed Standard Test Method.

In response to the COVID-19 pandemic, air cleaning technologies were promoted as useful tools for disinfecting public spaces and combating airborne pathogen transmission. However, no standard method exists to assess the potentially harmful byproduct formation from air cleaners. Through a consensus standard development process, a draft standard test method to assess portable air cleaner performance was developed, and a suite of air cleaners employing seven different technologies was tested.

Ventilation in a Residential Building Brings Outdoor NO Indoors with Limited Implications for VOC Oxidation from NO Radicals.

Energy-efficient residential building standards require the use of mechanical ventilation systems that replace indoor air with outdoor air. Transient outdoor pollution events can be transported indoors via the mechanical ventilation system and other outdoor air entry pathways and impact indoor air chemistry. In the spring of 2022, we observed elevated levels of NO (NO + NO) that originated outdoors, entering the National Institute of Standards and Technology (NIST) Net-Zero Energy Residential Test Facility through the mechanical ventilation system.

The persistence of smoke VOCs indoors: Partitioning, surface cleaning, and air cleaning in a smoke-contaminated house.

Wildfires are increasing in frequency, raising concerns that smoke can permeate indoor environments and expose people to chemical air contaminants. To study smoke transformations in indoor environments and evaluate mitigation strategies, we added smoke to a test house. Many volatile organic compounds (VOCs) persisted days following the smoke injection, providing a longer-term exposure pathway for humans.

Ozone Generation from a Germicidal Ultraviolet Lamp with Peak Emission at 222 nm.

Recent interest in commercial devices containing germicidal ultraviolet lamps with a peak emission wavelength at 222 nm (GUV222) has focused on mitigating virus transmission indoors while posing minimum risk to human tissue. However, 222 nm light can produce ozone (O) in air. O is an undesirable component of indoor air because of health impacts from acute to chronic exposure and its ability to degrade indoor air quality through oxidation chemistry.

Evaluation of a four-zone indoor exposure model for predicting TCPP concentrations in a low-energy test house.

Numerous chemicals have been detected in indoor environments that have potential impacts on occupant health and comfort. However, due to limited resources, it's infeasible to assess indoor exposure of each chemical for all indoor conditions through measurements alone. Hence, indoor exposure models have been developed to predict time-varied exposure for a wide range of sources and chemicals under different conditions.

Measurement of chemical emission rates from cigarette butts into air.

This study examined airborne emissions from cigarette butts for styrene, 2-methyl-2-cyclopenten-1-one, naphthalene, triacetin, and nicotine. Ten experiments were conducted by placing butts in a stainless steel chamber and measuring the chemical concentrations in chamber air. Emission rates were determined from the concentrations.

Influence of temperature, relative humidity, and water saturation on airborne emissions from cigarette butts.

With five trillion generated per year, cigarette butts are some of the most common litter worldwide. However, despite the potential environmental and human health risks from cigarette butts, little effort has been made to understand airborne emissions from cigarette butts. This study examined the influence of temperature, relative humidity and water saturation on airborne chemical emissions from cigarette butts.

Applicability of Spray Polyurethane Foam Ventilation Guideline for Do-It-Yourself Application Events.

Small two-component spray polyurethane foam (SPF) application kits are often applied by Do-It-Yourself (DIY) consumers. The United States Environmental Protection Agency (EPA) publishes a guideline for ventilating a space where SPF is being applied to minimize exposure to mists, vapors, particles and dust. This study sought to assess the applicability of the EPA ventilation guideline in protecting non-application areas of a house from exposure to SPF-associated emissions during a DIY application.

Evaluating IAQ and Energy Impacts of Ventilation in a Net-Zero Energy House Using a Coupled Model.

The National Institute of Standards and Technology constructed the Net-Zero Energy (NZE) Residential Test Facility to support the development and adoption of cost-effective NZE designs and technologies. In support of indoor air quality goals, contaminant source control approaches were implemented that minimized the use of products containing urea-formaldehyde resin and utilized products with relatively low volatile organic compound emissions. Indoor and outdoor concentrations of formaldehyde and acetaldehyde were measured approximately monthly for 15 months.

Formaldehyde Concentrations in a Net-Zero Energy House: Real-time Monitoring and Simulation.

Measured real-time formaldehyde concentrations in a net-zero energy house were compared to simulated concentrations from a recently-developed, coupled building energy and airflow/indoor air quality model. Measured and simulated formaldehyde concentrations in living spaces ranged from 4 ppb to 10 ppb (5 μg/m to 12 μg/m) while concentrations in the conditioned attic ranged from 13 ppb to 28 ppb (16 μg/m to 34 μg/m). During the 15 minutes the heat recovery ventilator was off each hour, the measured concentration in a bedroom increased by 1 ppb (1.

Measuring and Characterizing Tris(2-chloro-1-methylethyl) Phosphate Emission from Open Cell Spray Polyurethane Foam.

Understanding emission of Tris(2-chloro-1-methylethyl) Phosphate (TCPP) from spray polyurethane foam (SPF) insulation will contribute to the assessment of exposure to TCPP in indoor environments. This study aims to: (1) develop a method to determine the gas phase concentration of TCPP in equilibrium with the material phase (y) for open cell SPF, (2) determine the partition coefficient for TCPP between air and SPF (), and (3) examine the influence of temperature on y and . The emission of TCPP from two kinds of open cell SPF in a closed micro-chamber without flow are being tested.

Ultrafine particle removal and ozone generation by in-duct electrostatic precipitators.

Human exposure to airborne ultrafine particles (UFP, < 100 nm) has been shown to have adverse health effects and can be elevated in buildings. In-duct electrostatic precipitator filters (ESP) have been shown to be an effective particulate control device for reducing UFP concentrations (20-100 nm) in buildings, although they have the potential to increase indoor ozone concentrations. This study investigated residential ESP filters to reduce ultrafine particles between 4 to 15 nm and quantified the resulting ozone generation.

Characterization of particulate matter size distributions and indoor concentrations from kerosene and diesel lamps.

Unlabelled: Over one-quarter of the world's population relies on fuel-based lighting. Kerosene lamps are often located in close proximity to users, potentially increasing the risk for respiratory illnesses and lung cancer. Particulate matter concentrations resulting from cook stoves have been extensively studied in the literature.

Chlorine dioxide reactions with indoor materials during building disinfection: surface uptake.

Chlorine dioxide received attention as a building disinfectant in the wake of Bacillus anthracis contamination of several large buildings in the fall of 2001. It is increasingly used for the disinfection of homes and other indoor environments afflicted by mold. However, little is known regarding the interaction of chlorine dioxide and indoor materials, particularly as related to the removal of chlorine dioxide from air.

Methyl bromide as a building disinfectant: interaction with indoor materials and resulting byproduct formation.

Several buildings were contaminated with Bacillus anthracis in the fall of 2001. These events required consideration of how to disinfect large indoor spaces for continued worker occupation. The interactions of gaseous disinfectants with indoor materials may inhibit the disinfection process, cause persistence of the disinfectant, and lead to possible byproduct formation and persistence.