Characterizing peak exposure of secondhand smoke using a real-time PM2.5 monitor.

Although short-duration elevated exposures (peak exposures) to pollutants may trigger adverse acute effects, epidemiological studies to understand their influence on different health effects are hampered by lack of methods for objectively identifying peaks. Secondhand smoke from cigarettes (SHS) in the residential environment can lead to peak exposures. The aim of this study was to explore whether peaks in continuous PM2.5 data can indicate SHS exposure. A total of 41 children (21 with and 20 without SHS exposure based on self-report) from 28 families in New York City (NY, USA) were recruited. Both personal and residential continuous PM2.5 monitoring were performed for five consecutive days using MicroPEM sensors (RTI International, USA). A threshold detection method based on cumulative distribution function was developed to identify peaks. When children were home, the mean accumulated peak area (APA) for peak exposures was 297 ± 325 hour*µg/m3 for children from smoking families and six times that of the APA from non-smoking families (~50 ± 54 hour*µg/m3 ). Average PM2.5 mass concentrations for SHS exposed and unexposed children were 24 ± 15 µg/m3 and 15 ± 9 µg/m3 , respectively. The average SHS exposure duration represents ~5% of total exposure time, but ~13% of children's total PM2.5 exposure dose, equivalent to an additional 2.6 µg/m3 per day. This study demonstrated the feasibility of peak analysis for quantifying SHS exposure. The developed method can be adopted more widely to support epidemiology studies on impacts of short-term exposures.

Biogas Stoves Reduce Firewood Use, Household Air Pollution, and Hospital Visits in Odisha, India.

Traditional cooking using biomass is associated with ill health, local environmental degradation, and regional climate change. Clean stoves (liquefied petroleum gas (LPG), biogas, and electric) are heralded as a solution, but few studies have demonstrated their environmental health benefits in field settings. We analyzed the impact of mainly biogas (as well as electric and LPG) stove use on social, environmental, and health outcomes in two districts in Odisha, India, where the Indian government has promoted household biogas. We established a cross-sectional observational cohort of 105 households that use either traditional mud stoves or improved cookstoves (ICS). Our multidisciplinary team conducted surveys, environmental air sampling, fuel weighing, and health measurements. We examined associations between traditional or improved stove use and primary outcomes, stratifying households by proximity to major industrial plants. ICS use was associated with 91% reduced use of firewood (p < 0.01), substantial time savings for primary cooks, a 72% reduction in PM2.5, a 78% reduction in PAH levels, and significant reductions in water-soluble organic carbon and nitrogen (p < 0.01) in household air samples. ICS use was associated with reduced time in the hospital with acute respiratory infection and reduced diastolic blood pressure but not with other health measurements. We find many significant gains from promoting rural biogas stoves in a context in which traditional stove use persists, although pollution levels in ICS households still remained above WHO guidelines.

Building characterization and aerosol infiltration into a naturally ventilated three-story apartment building.

Understanding infiltration of outdoor pollutants was an integral part of the Brooklyn Traffic Real-Time Ambient Pollutant Penetration and Environmental Dispersion (B-TRAPPED) study. For this reason, the structural and air exchange properties of the three-story row house in Brooklyn, NY, USA, that was used in the B-TRAPPED experiments were fully characterized. Factors investigated included representativeness of the construction and impact of building design features on the natural ventilation and infiltration of outdoor aerosol. Both blower door and perfluorocarbon tracer (PFT) air exchange rate (AER) experiments showed that the ventilation rates of the building were quite typical of similar structures in the New York City (NYC) metropolitan area. Indoor/outdoor (I/O) aerosol count ratios by particle size were comparable to a similar vintage naturally ventilated building in Boston, MA, USA. I/O ratio analyses were consistent with literature findings and showed I/O ratios ranging from 0.310 to 0.601, varying across particle sizes (from 0.3 to 5.0 [corrected] mum) and between first and second floor apartments. An effort to apply the rebound method of Thatcher et al. (Aerosol Sci. Technol., 2003, 37, 847-864) in determining aerosol infiltration rates proved unsuccessful due to unexpectedly long (>60 min) equilibration times after the filtration period. Uninsulated interior wall renovations in the study house created a cavity that resulted in a large intermediate dead volume (for infiltration) that apparently could not be accommodated by a simple infiltration model. Simple two-compartment models evidently have finite application limitations for even modestly complex settings.

The Brooklyn traffic real-time ambient pollutant penetration and environmental dispersion (B-TRAPPED) field study methodology.

The Brooklyn Traffic Real-Time Ambient Pollutant Penetration and Environmental Dispersion (B-TRAPPED) field study examined indoor and outdoor exposure to traffic-generated air pollution by studying the individual processes of generation of traffic emissions, transport and dispersion of air contaminants along a roadway, and infiltration of the contaminants into a residence. Real-time instrumentation was used to obtain highly resolved time-series concentration profiles for a number of air pollutants. The B-TRAPPED field study was conducted in the residential Sunset Park neighborhood of Brooklyn, NY, USA, in May 2005. The neighborhood contained the Gowanus Expressway (Interstate 278), a major arterial road (4(th) Avenue), and residential side streets running perpendicular to the Gowanus Expressway and 4(th) Avenue. Synchronized measurements were obtained inside a test house, just outside the test house façade, and along the urban residential street canyon on which the house was located. A trailer containing Federal Reference Method (FRM) and real-time monitors was located next to the Gowanus Expressway to assess the source. Ultrafine particulate matter (PM), PM(2.5), nitrogen oxides (NO(x)), sulfur dioxide (SO(2)), carbon monoxide (CO), carbon dioxide (CO(2)), temperature, relative humidity, and wind speed and direction were monitored. Different sampling schemes were devised to focus on dispersion along the street canyon or infiltration into the test house. Results were obtained for ultrafine PM, PM(2.5), criteria gases, and wind conditions from sampling schemes focused on street canyon dispersion and infiltration. For comparison, the ultrafine PM and PM(2.5) results were compared with an existing data set from the Los Angeles area, and the criteria gas data were compared with measurements from a Vancouver epidemiologic study. Measured ultrafine PM and PM(2.5) concentration levels along the residential urban street canyon and at the test house façade in Sunset Park were demonstrated to be comparable to traffic levels at an arterial road and slightly higher than those in a residential area of Los Angeles. Indoor ultrafine PM levels were roughly 3-10 times lower than outdoor levels, depending on the monitor location. CO, NO(2), and SO(2) levels were shown to be similar to values that produced increased risk of chronic obstructive pulmonary disease hospitalizations in the Vancouver studies.

Particulate Matter 2.5 Exposure and Self-Reported Use of Wood Stoves and Other Indoor Combustion Sources in Urban Nonsmoking Homes in Norway.

Few studies have examined particulate matter (PM) exposure from self-reported use of wood stoves and other indoor combustion sources in urban settings in developed countries. We measured concentrations of indoor PM < 2.5 microns (PM2.5) for one week with the MicroPEM™ nephelometer in 36 households in the greater Oslo, Norway metropolitan area. We examined indoor PM2.5 levels in relation to use of wood stoves and other combustion sources during a 7 day monitoring period using mixed effects linear models with adjustment for ambient PM2.5 levels. Mean hourly indoor PM2.5 concentrations were higher (p = 0.04) for the 14 homes with wood stove use (15.6 µg/m3) than for the 22 homes without (12.6 µg/m3). Moreover, mean hourly PM2.5 was higher (p = 0.001) for use of wood stoves made before 1997 (6 homes, 20.2 µg/m3), when wood stove emission limits were instituted in Norway, compared to newer wood stoves (8 homes, 11.9 µg/m3) which had mean hourly values similar to control homes. Increased PM2.5 levels during diary-reported burning of candles was detected independently of concomitant wood stove use. These results suggest that self-reported use of wood stoves, particularly older stoves, and other combustion sources, such as candles, are associated with indoor PM2.5 measurements in an urban population from a high income country.

Real-Time Investigation of Tuberculosis Transmission: Developing the Respiratory Aerosol Sampling Chamber (RASC).

Knowledge of the airborne nature of respiratory disease transmission owes much to the pioneering experiments of Wells and Riley over half a century ago. However, the mechanical, physiological, and immunopathological processes which drive the production of infectious aerosols by a diseased host remain poorly understood. Similarly, very little is known about the specific physiological, metabolic and morphological adaptations which enable pathogens such as Mycobacterium tuberculosis (Mtb) to exit the infected host, survive exposure to the external environment during airborne carriage, and adopt a form that is able to enter the respiratory tract of a new host, avoiding innate immune and physical defenses to establish a nascent infection. As a first step towards addressing these fundamental knowledge gaps which are central to any efforts to interrupt disease transmission, we developed and characterized a small personal clean room comprising an array of sampling devices which enable isolation and representative sampling of airborne particles and organic matter from tuberculosis (TB) patients. The complete unit, termed the Respiratory Aerosol Sampling Chamber (RASC), is instrumented to provide real-time information about the particulate output of a single patient, and to capture samples via a suite of particulate impingers, impactors and filters. Applying the RASC in a clinical setting, we demonstrate that a combination of molecular and microbiological assays, as well as imaging by fluorescence and scanning electron microscopy, can be applied to investigate the identity, viability, and morphology of isolated aerosolized particles. Importantly, from a preliminary panel of active TB patients, we observed the real-time production of large numbers of airborne particles including Mtb, as confirmed by microbiological culture and polymerase chain reaction (PCR) genotyping. Moreover, direct imaging of captured samples revealed the presence of multiple rod-like Mtb organisms whose physical dimensions suggested the capacity for travel deep into the alveolar spaces of the human lung.

Health and household air pollution from solid fuel use: the need for improved exposure assessment.

BACKGROUND: Nearly 3 billion people worldwide rely on solid fuel combustion to meet basic household energy needs. The resulting exposure to air pollution causes an estimated 4.5% of the global burden of disease. Large variability and a lack of resources for research and development have resulted in highly uncertain exposure estimates. OBJECTIVE: We sought to identify research priorities for exposure assessment that will more accurately and precisely define exposure-response relationships of household air pollution necessary to inform future cleaner-burning cookstove dissemination programs. DATA SOURCES: As part of an international workshop in May 2011, an expert group characterized the state of the science and developed recommendations for exposure assessment of household air pollution. SYNTHESIS: The following priority research areas were identified to explain variability and reduce uncertainty of household air pollution exposure measurements: improved characterization of spatial and temporal variability for studies examining both short- and long-term health effects; development and validation of measurement technology and approaches to conduct complex exposure assessments in resource-limited settings with a large range of pollutant concentrations; and development and validation of biomarkers for estimating dose. Addressing these priority research areas, which will inherently require an increased allocation of resources for cookstove research, will lead to better characterization of exposure-response relationships. CONCLUSIONS: Although the type and extent of exposure assessment will necessarily depend on the goal and design of the cookstove study, without improved understanding of exposure-response relationships, the level of air pollution reduction necessary to meet the health targets of cookstove interventions will remain uncertain.

ISEA2007 panel: integration of better exposure characterizations into disaster preparedness for responders and the public.

An expert panel was convened in October 2007 at the International Society for Exposure Analysis Annual Meeting in Durham, NC, entitled "The Path Forward in Disaster Preparedness Since WTC-Exposure Characterization and Mitigation: Substantial Unfinished Business!" The panel prospectively discussed the critical exposure issues being overlooked during disaster responses and highlighted the needs for an optimal blending of exposure characterizations and hazard controls within disaster settings. The cases were made that effective and timely exposure characterizations must be applied during responses to any disaster, whether terrorist, manmade, or natural in origin. The consistent application of exposure sciences across acute and chronic disaster timelines will assure that the most effective strategies are applied to collect the needed information to guide risk characterization and management approaches. Exposure sciences must be effectively applied across all phases of a disaster (defined as rescue, reentry, recovery, and rehabitation-the four Rs) to appropriately characterize risks and guide risk-mitigation approaches. Failure to adequately characterize and control hazardous exposures increases the likelihood of excess morbidity and mortality. Advancing the infrastructure and the technologies to collect the right exposure information before, during, and immediately after disasters would advance our ability to define risks and protect responders and the public better. The panel provided conclusions, recommendations, and next steps toward effective and timely integration of better exposure science into disaster preparedness, including the need for a subsequent workshop to facilitate this integration. All panel presentations and a summary were uploaded to the ISES(1) website (http://www.iseaweb.org/Disaster_Preparedness/index.php).

Importance of the personal endotoxin cloud in school-age children with asthma.

BACKGROUND: A number of studies have observed associations between the amount of endotoxin in urban dust and chronic asthma severity, but a direct relationship between personal exposure to household endotoxin and acute asthma worsening has not yet been defined. OBJECTIVE: We sought to investigate the relationship between day-to-day changes in personal endotoxin exposure and asthma severity. METHODS: In the winter and spring of 1999 through 2000, endotoxin exposures were monitored in asthmatic schoolchildren by using portable, as opposed to stationary, monitors designed to measure inhalable and respirable particulate matter less than or equal to 2.5 and 10 microm in diameter. Children were followed with daily measurements of FEV(1) and asthma symptoms. RESULTS: Over a 24-hour period, median daily personal endotoxin exposures ranged from 0.08 EU/m(3) (measured at a particulate matter size range

Maximizing Data Quality in the Gravimetric Analysis of Personal Exposure Sample Filters.

The weighing of particle sampler filters has always been plagued by problems in the weighing environment: humidity, temperature, drafts, vibration, and electrostatic charges on the filters. These are particularly critical for samples with small mass collections, such as those encountered in personal exposure monitoring for PM25. While modern electronic balances offer substantial reductions in the effects of temperature and vibration, these balances are still sensitive to factors such as thermal drafts and zero shifts from tilting. Drafts may be controlled through room ventilation modifications, and zero drift can be eliminated by computer-assisted data collection algorithms. A less well-understood influence is static charge, which is often controlled with a simple radioactive neutralizer. Although radioactive neutralizes are effective, their effectiveness decays rapidly with time, and their use may be objectionable for nontechnical reasons. We have analyzed a number of environmental factors influencing gravimetric microbalance operations and have developed methods to minimize or eliminate them.