Correction: Barkjohn et al. Correction and Accuracy of PurpleAir PM Measurements for Extreme Wildfire Smoke. 2022, , 9669.

In the original publication [...

Air Quality Sensor Experts Convene: Current Quality Assurance Considerations for Credible Data.

Air sensors can provide valuable non-regulatory and supplemental data as they can be affordably deployed in large numbers and stationed in remote areas far away from regulatory air monitoring stations. Air sensors have inherent limitations that are critical to understand before collecting and interpreting the data. Many of these limitations are mechanistic in nature, which will require technological advances.

Nasal oxidative stress mediating the effects of colder temperature exposure on pediatric asthma symptoms.

Background: Colder temperature exposure is a known trigger for pediatric asthma exacerbation. The induction of oxidative stress is a known pathophysiologic pathway for asthma exacerbation. However, the role of oxidative stress in linking colder temperature exposure and worsened pediatric asthma symptoms is poorly understood.

Associations between personal apparent temperature exposures and asthma symptoms in children with asthma.

Ambient temperature and relative humidity can affect asthma symptoms. Apparent temperature is a measure of temperature perceived by humans that takes into account the effect of humidity. However, the potential link between personal exposures to apparent temperature and asthma symptoms has not been investigated.

An analysis of degradation in low-cost particulate matter sensors.

Low-cost sensors (LCS) are increasingly being used to measure fine particulate matter (PM) concentrations in cities around the world. One of the most commonly deployed LCS is the PurpleAir with ~ 15,000 sensors deployed in the United States, alone. PurpleAir measurements are widely used by the public to evaluate PM levels in their neighborhoods.

Correction and Accuracy of PurpleAir PM Measurements for Extreme Wildfire Smoke.

PurpleAir particulate matter (PM) sensors are increasingly used in the United States and other countries for real-time air quality information, particularly during wildfire smoke episodes. Uncorrected PurpleAir data can be biased and may exhibit a nonlinear response at extreme smoke concentrations (>300 µg/m3). This bias and nonlinearity result in a disagreement with the traditional ambient monitoring network, leading to the public’s confusion during smoke episodes.

Oral cavity response to air pollutant exposure and association with pulmonary inflammation and symptoms in asthmatic children.

Exposure to fine particulate matter (PM) and ozone (O) may lead to inflammation and oxidative damage in the oral cavity, which is hypothesized to contribute to the worsening of airway inflammation and asthma symptoms. In this panel study of 43 asthmatic children aged 5-13 years old, each child had 4 clinic visits with a 2-week interval between two consecutive visits. At each visit, saliva samples were collected and subsequently analyzed for interleukin 6 (IL-6) and eosinophil cationic protein (ECP) as biomarkers of inflammation and malondialdehyde (MDA) as a biomarker of oxidative stress in the oral cavity.

Development and Application of a United States wide correction for PM data collected with the PurpleAir sensor.

PurpleAir sensors, which measure particulate matter (PM), are widely used by individuals, community groups, and other organizations including state and local air monitoring agencies. PurpleAir sensors comprise a massive global network of more than 10,000 sensors. Previous performance evaluations have typically studied a limited number of PurpleAir sensors in small geographic areas or laboratory environments.

Role of endogenous melatonin in pathophysiologic and oxidative stress responses to personal air pollutant exposures in asthmatic children.

Background: Heightening oxidative stress and inflammation is an important pathophysiological mechanism underlying air pollution health effects in people with asthma. Melatonin can suppress oxidative stress and inflammation in pulmonary and circulatory systems. However, the role of melatonin in the oxidative stress and physiological responses to air pollution exposure has not been examined in children with asthma.

Deliberating Performance Targets: Follow-on workshop discussing PM, NO, CO, and SO air sensor targets.

The use of air sensor technology is increasing worldwide for a variety of applications, however, with significant variability in data quality. The United States Environmental Protection Agency held a workshop in July 2019 to deliberate possible performance targets for air sensors measuring particles with aerodynamic diameters of 10 μm or less (PM), nitrogen dioxide (NO), carbon monoxide (CO), and sulfur dioxide (SO). These performance targets were discussed from the perspective of non-regulatory applications and with the sensors operating primarily in a stationary mode in outdoor environments.

Creating Clean Air Spaces During Wildland Fire Smoke Episodes: Web Summit Summary.

Effective strategies to reduce indoor air pollutant concentrations during wildfire smoke events are critically needed. Worldwide, communities in areas prone to wildfires may suffer from annual smoke exposure events lasting from days to weeks. In addition, there are many areas of the world where high pollution events are common and where methods employed to reduce exposure to pollution may have relevance to wildfire smoke pollution episodes and vice versa.

Personal Exposure to PM Oxidative Potential in Association with Pulmonary Pathophysiologic Outcomes in Children with Asthma.

Fine particulate matter (PM) with a higher oxidative potential has been thought to be more detrimental to pulmonary health. We aim to investigate the associations between personal exposure to PM oxidative potential and pulmonary outcomes in asthmatic children. We measured each of the 43 asthmatic children 4 times for airway mechanics, lung function, airway inflammation, and asthma symptom scores.

Children's microenvironmental exposure to PM and ozone and the impact of indoor air filtration.

Background: In highly polluted urban areas, personal exposure to PM and O occur daily in various microenvironments. Identifying which microenvironments contribute most to exposure can pinpoint effective exposure reduction strategies and mitigate adverse health impacts.

Methods: This work uses real-time sensors to assess the exposures of children with asthma (N = 39) in Shanghai, quantifying microenvironmental exposure to PM and O.

Malondialdehyde in Nasal Fluid: A Biomarker for Monitoring Asthma Control in Relation to Air Pollution Exposure.

Fine particulate matter (PM) and ozone (O) may exert oxidative damage in the nose, which is hypothesized to be associated with worsened asthma symptoms. This study, hence, is to explore whether an oxidative stress biomarker, malondialdehyde (MDA) in the nasal fluid, has the potential to aid personalized asthma control. In a panel study of 43 asthmatic children, 5-13 years old, each child was measured 4 times with a 2-week interval between consecutive clinic visits.

Real-time measurements of PM and ozone to assess the effectiveness of residential indoor air filtration in Shanghai homes.

Portable air cleaners are increasingly used in polluted areas in an attempt to reduce human exposure; however, there has been limited work characterizing their effectiveness at reducing exposure. With this in mind, we recruited forty-three children with asthma from suburban Shanghai and deployed air cleaners (with HEPA and activated carbon filters) in their bedrooms. During both 2-week filtration and non-filtration periods, low-cost PM and O air monitors were used to measure pollutants indoors, outdoors, and for personal exposure.

Connecting Air Quality with Emotional Well-Being and Neighborhood Infrastructure in a US City.

Cities in the United States have announced initiatives to become more sustainable, healthy, resilient, livable, and environmentally friendly. However, indicators for measuring all outcomes related to these targets and the synergies between them have not been well defined or studied. One such relationship is the linkage between air quality with emotional well-being (EWB) and neighborhood infrastructure.

Association Between Bedroom Particulate Matter Filtration and Changes in Airway Pathophysiology in Children With Asthma.

Importance: Fine particles (particulate matter 2.5 μm [PM2.5]), a ubiquitous air pollutant, can deposit in the small airways that play a vital role in asthma.

Associations of personal exposure to air pollutants with airway mechanics in children with asthma.

Background: The importance of airway mechanics has been increasingly recognized in pediatric asthma. However, no studies have examined responses of airway mechanics to air pollution exposure in asthmatic children.

Methods: In this panel study involving indoor air filtration manipulation that created a large gradient of personal exposure to PM, the airway mechanics and lung function of 43 asthmatic children 5-13 years old in a suburb of Shanghai were measured four times within 3 consecutive months.

The impact of household air cleaners on the oxidative potential of PM and the role of metals and sources associated with indoor and outdoor exposure.

The health effects associated with human exposure to airborne fine particulate matter (PM) have been linked to the ability of PM to facilitate the production of excess cellular reactive oxygen species (oxidative potential). Concern about the adverse human health impacts of PM has led to the increased use of indoor air cleaners to improve indoor air quality, which can be an important environment for PM exposure. However, the degree to which the oxidative potential of indoor and personal PM can be influenced by an indoor air cleaner remains unclear.

Using low-cost sensors to monitor indoor, outdoor, and personal ozone concentrations in Beijing, China.

High concentrations of ground-level ozone (O) have been measured outdoors across China but there are limited measurements of O in microenvironments, including in homes, and for personal exposure. This highlights the need for cheaper methods to accurately make these measurements and to better capture fine-scale spatial variability in O across cities. With this in mind, we conducted a pilot study at six homes in Beijing, China, over 12 days to evaluate the use of portable, low-cost, time-resolved monitors for measuring O indoors and outdoors.

The impact of household air cleaners on the chemical composition and children's exposure to PM metal sources in suburban Shanghai.

Increased public awareness of the health impacts of atmospheric fine particulate matter (PM) has led to increased demand and deployment of indoor air cleaners. Yet, questions still remain about the effectiveness of indoor air cleaners on indoor PM concentrations and personal exposure to potentially hazardous components of PM. Metals in PM have been associated with adverse health outcomes, so knowledge of their sources in urban indoor and outdoor areas and how exposures are influenced by indoor air cleaners would be beneficial for public health interventions.

Sources of volatile organic compounds in suburban homes in Shanghai, China, and the impact of air filtration on compound concentrations.

Air pollution in China is an ongoing concern, with subsets of the population (e.g., asthmatic children) especially susceptible to the associated health effects.