Development of a Consolidated Health Facility Masterlist Using Data From Polio Electronic Surveillance in the World Health Organization African Region.

Geospatial data reporting from surveillance and immunization efforts is a key aspect of the World Health Organization (WHO) Global Polio Eradication Initiative in Africa. These activities are coordinated through the WHO Regional Office for Africa Geographic Information Systems Centre. To ensure the accuracy of field-collected data, the WHO Regional Office for Africa Geographic Information Systems Centre has developed mobile phone apps such as electronic surveillance (eSURV) and integrated supportive supervision (ISS) geospatial data collection programs. While eSURV and ISS have played a vital role in efforts to eradicate polio and control other communicable diseases in Africa, disease surveillance efforts have been hampered by incomplete and inaccurate listings of health care sites throughout the continent. To address this shortcoming, data compiled from eSURV and ISS are being used to develop, update, and validate a Health Facility master list for the WHO African region that contains comprehensive listings of the names, locations, and types of health facilities in each member state. The WHO and Ministry of Health field officers are responsible for documenting and transmitting the relevant geospatial location information regarding health facilities and traditional medicine sites using the eSURV and ISS form; this information is then used to update the Health Facility master list and is also made available to national ministries of health to update their respective health facility lists. This consolidation of health facility information into a single registry is expected to improve disease surveillance and facilitate epidemiologic research for the Global Polio Eradication Initiative, as well as aid public health efforts directed at other diseases across the African continent. This review examines active surveillance using eSURV at the district, country, and regional levels, highlighting its role in supporting polio surveillance and immunization efforts, as well as its potential to serve as a fundamental basis for broader public health initiatives and research throughout Africa.

Leveraging Polio Geographic Information System Platforms in the African Region for Mitigating COVID-19 Contact Tracing and Surveillance Challenges: Viewpoint.

BACKGROUND: The ongoing COVID-19 pandemic in Africa is an urgent public health crisis. Estimated models projected over 150,000 deaths and 4,600,000 hospitalizations in the first year of the disease in the absence of adequate interventions. Therefore, electronic contact tracing and surveillance have critical roles in decreasing COVID-19 transmission; yet, if not conducted properly, these methods can rapidly become a bottleneck for synchronized data collection, case detection, and case management. While the continent is currently reporting relatively low COVID-19 cases, digitized contact tracing mechanisms and surveillance reporting are necessary for standardizing real-time reporting of new chains of infection in order to quickly reverse growing trends and halt the pandemic. OBJECTIVE: This paper aims to describe a COVID-19 contact tracing smartphone app that includes health facility surveillance with a real-time visualization platform. The app was developed by the AFRO (African Regional Office) GIS (geographic information system) Center, in collaboration with the World Health Organization (WHO) emergency preparedness and response team. The app was developed through the expertise and experience gained from numerous digital apps that had been developed for polio surveillance and immunization via the WHO's polio program in the African region. METHODS: We repurposed the GIS infrastructures of the polio program and the database structure that relies on mobile data collection that is built on the Open Data Kit. We harnessed the technology for visualization of real-time COVID-19 data using dynamic dashboards built on Power BI, ArcGIS Online, and Tableau. The contact tracing app was developed with the pragmatic considerations of COVID-19 peculiarities. The app underwent testing by field surveillance colleagues to meet the requirements of linking contacts to cases and monitoring chains of transmission. The health facility surveillance app was developed from the knowledge and assessment of models of surveillance at the health facility level for other diseases of public health importance. The Integrated Supportive Supervision app was added as an appendage to the pre-existing paper-based surveillance form. These two mobile apps collected information on cases and contact tracing, alongside alert information on COVID-19 reports at the health facility level; the information was linked to visualization platforms in order to enable actionable insights. RESULTS: The contact tracing app and platform were piloted between April and June 2020; they were then put to use in Zimbabwe, Benin, Cameroon, Uganda, Nigeria, and South Sudan, and their use has generated some palpable successes with respect to COVID-19 surveillance. However, the COVID-19 health facility-based surveillance app has been used more extensively, as it has been used in 27 countries in the region. CONCLUSIONS: In light of the above information, this paper was written to give an overview of the app and visualization platform development, app and platform deployment, ease of replicability, and preliminary outcome evaluation of their use in the field. From a regional perspective, integration of contact tracing and surveillance data into one platform provides the AFRO with a more accurate method of monitoring countries' efforts in their response to COVID-19, while guiding public health decisions and the assessment of risk of COVID-19.

Lessons learned from the Global Polio Eradication Initiative: A roadmap for the international COVID-19 vaccination campaign.

The COVID-19 vaccine is lauded by many as one of the greatest accomplishments in modern medicine, with the potential to definitively contain the deadliest pandemic of the last century. With the vaccine rollout now underway in the developing world, a robust, methodical, and swift global distribution effort is required to ensure that it will be done in an equitable manner. Taking into account the vast geographic, socioeconomic, cultural, and political diversity of countries around the world, global vaccination efforts have historically required multifaceted, time consuming, and labor-intensive approaches to be effective. However, with over 33 years of experience from the Global Polio Eradication Initiative - an international health initiative aimed at eradicating poliomyelitis - the COVID-19 vaccination campaign does not have to be approached blindly. Using lessons learned from the Global Polio Eradication Initiative, this paper aims to identify the supply- and demand-side barriers to the success of the international COVID-19 vaccination effort, and ways each can be overcome. Most notably, health systems shortcomings, political and cultural messaging, and civil unrest and violent conflict serve as daunting obstacles to the success of the COVID-19 vaccination campaign. The Global Polio Eradication Initiative has been able to overcome many of these same obstacles with innovative strategies such as context-specific microplanning, robust health surveillance systems, and community-centered education and advocacy programs. Ultimately, while the Global Polio Eradication Initiative is still fighting the battle of polio eradication, it has provided a roadmap for the COVID-19 vaccination campaign to be executed in a more swift and equitable manner.

Application of the Geographic Information System (GIS) in immunisation service delivery; its use in the 2017/2018 measles vaccination campaign in Nigeria.

BACKGROUND: As global effort is made towards measles elimination, the use of innovative technology to enhance planning for the campaign has become critical. GIS technology has been applied to track polio vaccination activities in Nigeria with encouraging outcomes. Despite numerous measles vaccination campaigns after the first catch up campaign in 2005, sub-optimal outcomes of previous measles supplemental immunization activities necessitated the use of innovative ideas to achieve better outcomes especially when planning for the 2017/2018 measles vaccination campaign. This led to the application of the use of the GIS technology for the Northern states in 2017/2018 campaign. This study is a report of what was achieved with the use of the GIS in the 2017/2018 measles vaccination campaign in Nigeria. METHODS: GIS generated ward maps were used for the microplanning processes for the 2017/2018 measles vaccination campaign. These ward maps had estimates of the target population by settlements, the number and location of vaccination posts ensuring that a vaccination post is sited within one-kilometer radius of a settlement, and the number of teams needed to support the vaccination campaign as well as the catchment area and daily implementation plans. The ward microplans were verified by checking for accuracy and consistency of the target population, settlements, number of teams, vaccination posts and daily implementation work plans using a standard checklist. The ward maps were deployed into use for the measles vaccination campaign after the state team driven validation and verification by the National team (Government and Partners) RESULTS: The Northern states that applied the GIS technology had a closer operational target population to that on the verified microplan than those of the non-GIS technology states. Greater than 90% of the ward maps had all that is expected in the maps - i.e settlements, target populations, and vaccination posts captured, except Kaduna, Katsina and Adamawa states. Of all enumeration areas sampled during the post-campaign survey in states with GIS ward maps, none had a zero-vaccination coverage of the surveyed children, with the exception of one in Borno state that had security issues. In the post campaign coverage survey, the percentage of responses that gave vaccination post being too far as a reason for non-vaccination of children in the Northern zones that used GIS generated ward maps was less than half the rate seen in the southern zones where the GIS microplanning was not used. CONCLUSION: The use of GIS-generated wards maps improved the quality of ward micro plans and optimized the placement of vaccination posts, resulting in a significant reduction in zero-dose clusters found during the post campaign coverage survey.

National population mapping from sparse survey data: A hierarchical Bayesian modeling framework to account for uncertainty.

Population estimates are critical for government services, development projects, and public health campaigns. Such data are typically obtained through a national population and housing census. However, population estimates can quickly become inaccurate in localized areas, particularly where migration or displacement has occurred. Some conflict-affected and resource-poor countries have not conducted a census in over 10 y. We developed a hierarchical Bayesian model to estimate population numbers in small areas based on enumeration data from sample areas and nationwide information about administrative boundaries, building locations, settlement types, and other factors related to population density. We demonstrated this model by estimating population sizes in every 10- m grid cell in Nigeria with national coverage. These gridded population estimates and areal population totals derived from them are accompanied by estimates of uncertainty based on Bayesian posterior probabilities. The model had an overall error rate of 67 people per hectare (mean of absolute residuals) or 43% (using scaled residuals) for predictions in out-of-sample survey areas (approximately 3 ha each), with increased precision expected for aggregated population totals in larger areas. This statistical approach represents a significant step toward estimating populations at high resolution with national coverage in the absence of a complete and recent census, while also providing reliable estimates of uncertainty to support informed decision making.

Finding inhabited settlements and tracking vaccination progress: the application of satellite imagery analysis to guide the immunization response to confirmation of previously-undetected, ongoing endemic wild poliovirus transmission in Borno State, Nigeria.

BACKGROUND: Four wild polio-virus cases were reported in Borno State, Nigeria 2016, 1 year after Nigeria had been removed from the list of polio endemic countries by the World Health Organization. Resulting from Nigeria's decade long conflict with Boko Haram, health officials had been unable to access as much as 60% of the settlements in Borno, hindering vaccination and surveillance efforts. This lack of accessibility made it difficult for the government to assess the current population distribution within Borno. This study aimed to use high resolution, visible band satellite imagery to assess the habitation of inaccessible villages in Borno State. METHODS: Using high resolution (31-50 cm) imagery from DigitalGlobe, analysts evaluated the habitation status of settlements in Borno State identified by Nigeria's Vaccination Tracking System. The analysts looked at imagery of each settlement and, using vegetation (overgrowth vs. cleared) as a proxy for human habitation, classified settlements into three categories: inhabited, partially abandoned, and abandoned. Analysts also classified the intact percentage of each settlement starting at 0% (totally destroyed since last assessment) and increasing in 25% intervals through 100% (completely intact but not expanded) up to 200+% (more than doubled in size) by looking for destroyed buildings. These assessments were then used to adjust previously established population estimates for each settlement. These new population distributions were compared to vaccination efforts to determine the number of children under 5 unreached by vaccination teams. RESULTS: Of the 11,927 settlements assessed 3203 were assessed as abandoned (1892 of those completely destroyed), 662 as partially abandoned, and 8062 as fully inhabited as of December of 2017. Comparing the derived population estimates from the new assessments to previous assessment and the activities of vaccination teams shows that an estimated 180,155 of the 337,411 under five children who were unreached in 2016 were reached in 2017 (70.5% through vaccination efforts in previously inaccessible areas, 29.5% through displacement to accessible areas). CONCLUSIONS: This study's methodology provides important planning and situation awareness information to health workers in Borno, Nigeria, and may serve as a model for future data gathering efforts in inaccessible regions.

Comparison of Micro-Census Results for Magarya Ward, Wurno Local Government Area of Sokoto State, Nigeria, with Other Sources of Denominator Data.

Routine immunization coverage in Nigeria is suboptimal. In the northwestern state of Sokoto, an independent population-based survey for 2016 found immunization coverage with the third dose of Pentavalent vaccine to be 3%, whereas administrative coverage in 2016 was reported to be 69%. One possibility driving this large discrepancy is that administrative coverage is calculated using an under-estimated target population. Official population projections from the 2006 Census are based on state-specific standard population growth rates. Immunization target population estimates from other sources have not been independently validated. We conducted a micro-census in Magarya ward, Wurno Local Government Area of Sokoto state to obtain an accurate count of the total population living in the ward, and to compare these results with other sources of denominator data. We developed a precise micro-plan using satellite imagery, and used the navigation tool EpiSample v1 in the field to guide teams to each building, without duplications or omissions. The particular characteristics of the selected ward underscore the importance of using standardized shape files to draw precise boundaries for enumeration micro-plans. While the use of this methodology did not resolve the discrepancy between independent and administrative vaccination coverage rates, a simplified application can better define the target population for routine immunization services and estimate the number of children still unprotected from vaccine-preventable diseases.

Census-independent population mapping in northern Nigeria.

Although remote sensing has long been used to aid in the estimation of population, it has usually been in the context of spatial disaggregation of national census data, with the census counts serving both as observational data for specifying models and as constraints on model outputs. Here we present a framework for estimating populations from the bottom up, entirely independently of national census data, a critical need in areas without recent and reliable census data. To make observations of population density, we replace national census data with a microcensus, in which we enumerate population for a sample of small areas within the states of Kano and Kaduna in northern Nigeria. Using supervised texture-based classifiers with very high resolution satellite imagery, we produce a binary map of human settlement at 8-meter resolution across the two states and then a more refined classification consisting of 7 residential types and 1 non-residential type. Using the residential types and a model linking them to the population density observations, we produce population estimates across the two states in a gridded raster format, at approximately 90-meter resolution. We also demonstrate a simulation framework for capturing uncertainty and presenting estimates as prediction intervals for any region of interest of any size and composition within the study region. Used in concert with previously published demographic estimates, our population estimates allowed for predictions of the population under 5 in ten administrative wards that fit strongly with reference data collected during polio vaccination campaigns.

Mapping for Health in Cameroon: Polio Legacy and Beyond.

During the poliovirus outbreak in Cameroon from October 2013 to April 2015, the Ministry of Public Health's Expanded Program on Immunization requested technical support to improve mapping of health district boundaries and health facility locations for more effective planning and analysis of polio program data. In December 2015, teams collected data on settlements, health facilities, and other features using smartphones. These data, combined with high-resolution satellite imagery, were used to create new health area and health district boundaries, providing the most accurate health sector administrative boundaries to date for Cameroon. The new maps are useful to and used by the polio program as well as other public health programs within Cameroon such as the District Health Information System and the Emergency Operations Center, demonstrating the value of the Global Polio Eradication Initiative's legacy.

Advancing digital methods in the fight against communicable diseases.

Important advances are being made in the fight against communicable diseases by using new digital tools. While they can be a challenge to deploy at-scale, GPS-enabled smartphones, electronic dashboards and computer models have multiple benefits. They can facilitate program operations, lead to new insights about the disease transmission and support strategic planning. Today, tools such as these are used to vaccinate more children against polio in Nigeria, reduce the malaria burden in Zambia and help predict the spread of the Ebola epidemic in West Africa.

Improving polio vaccination coverage in Nigeria through the use of geographic information system technology.

BACKGROUND: Historically, microplanning for polio vaccination campaigns in Nigeria relied on inaccurate and incomplete hand-drawn maps, resulting in the exclusion of entire settlements and missed children. The goal of this work was to create accurate, coordinate-based maps for 8 polio-endemic states in northern Nigeria to improve microplanning and support tracking of vaccination teams, thereby enhancing coverage, supervision, and accountability. METHODS: Settlement features were identified in the target states, using high-resolution satellite imagery. Field teams collected names and geocoordinates for each settlement feature, with the help of local guides. Global position system (GPS) tracking of vaccination teams was conducted in selected areas and daily feedback provided to supervisors. RESULTS: Geographic information system (GIS)-based maps were created for 2238 wards in the 8 target states. The resulting microplans included all settlements and more-efficient team assignments, owing to the improved spatial reference. GPS tracking was conducted in 111 high-risk local government areas, resulting in improved team performance and the identification of missed/poorly covered settlements. CONCLUSIONS: Accurate and complete maps are a necessary part of an effective polio microplan, and tracking vaccinators gives supervisors a tool to ensure that all settlements are visited.

Progress toward poliomyelitis eradication in Nigeria.

BACKGROUND: Transmission of wild poliovirus (WPV) has never been interrupted in Afghanistan, Pakistan, and Nigeria. Since 2003, infections with WPV of Nigerian origin have been detected in 25 polio-free countries. In 2012, the Nigerian government created an emergency operations center and implemented a national emergency action plan to eradicate polio. The 2013 revision of this plan prioritized (1) improving the quality of supplemental immunization activities (SIAs), (2) implementing strategies to reach underserved populations, (3) adopting special approaches in security-compromised areas, (4) improving outbreak response, (5) enhancing routine immunization and activities implemented between SIAs, and (6) strengthening surveillance. This report summarizes implementation of these activities during a period of unprecedented insecurity and violence, including the killing of health workers and the onset of a state of emergency in the northeast zone. METHODS: This report reviews management strategies, innovations, trends in case counts, vaccination and social mobilization activities, and surveillance and monitoring data to assess progress in polio eradication in Nigeria. RESULTS: Nigeria has made significant improvements in the management of polio eradication initiative (pei) activities with marked improvement in the quality of SIAs, as measured by lot quality assurance sampling (LQAS). Comparing results from February 2012 with results from December 2013, the proportion of local government areas (LGAs) conducting LQAS in the 11 high-risk states at the ≥90% pass/fail threshold increased from 7% to 42%, and the proportion at the 80%-89% threshold increased from 9% to 30%. During January-December 2013, 53 polio cases were reported from 26 LGAs in 9 states in Nigeria, compared with 122 cases reported from 13 states in 2012. No cases of WPV type 3 infection have been reported since November 2012. In 2013, no polio cases due to any poliovirus type were detected in the northwest sanctuaries of Nigeria. In the second half of 2013, WPV transmission was restricted to Kano, Borno, Bauchi, and Taraba states. Despite considerable progress, 24 LGAs in 2012 and 7 LGAs in 2013 reported ≥2 cases, and WPV continued to circulate in 8 LGAs that had cases in 2012. Campaign activities were negatively impacted by insecurity and violence in Borno and Kano states. CONCLUSIONS: Efforts to interrupt transmission remain impeded by poor SIA implementation in localized areas, anti-polio vaccine sentiment, and limited access to vaccinate children because of insecurity. Sustained improvement in SIA quality, surveillance, and outbreak response and special strategies in security-compromised areas are needed to interrupt WPV transmission in 2014.

Development and application of a sensitive method to determine concentrations of acrolein and other carbonyls in ambient air.

Acrolein, an unsaturated aldehyde, has been identified as one of the most important toxic air pollutants in recent assessments of ambient air quality. Current methods for determining acrolein concentrations, however, suffer from poor sensitivity, selectivity, and reproducibility. The collection and analysis of unsaturated carbonyls, and acrolein in particular, is complicated by unstable derivatives, coelution of similar compounds, and ozone interference. The primary objective of this research was to develop an analytical method to measure acrolein and other volatile carbonyls present in low part-per-trillion concentrations in ambient air samples obtained over short sampling periods. The method we devised uses a mist chamber in which carbonyls from air samples form water-soluble adducts with bisulfite in the chamber solution, effectively trapping the carbonyls in the solution. The mist chamber methodology proved effective, with collection efficiency for acrolein of at least 70% for each mist chamber at a flow rate of approximately 17 L/min. After the sample collection, the carbonyls are liberated from the bisulfite adducts through the addition of hydrogen peroxide, which converts the bisulfite to sulfate, reversing the bisulfite addition reaction. The free carbonyls are then derivatized by o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA*), which stabilizes the analytes and makes them easier to detect by electron-capture negative ionization mass spectrometry (ECNI-MS). The derivatives are then extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The mist chamber method was applied in a field test to determine the extent of acrolein in ambient air near the Peace Bridge plaza in Buffalo, New York, an area of heavy traffic near a major border crossing between the United States and Canada. In addition, XAD-2 adsorbent cartridges coated with 2-(hydroxymethyl)piperidine (2-HMP) according to Occupational Safety and Health Administration (OSHA) Method 52 and passive samplers based on the use of dansylhydrazine (DNSH) were deployed at this location at the same time, which provided the opportunity to compare methods. The mist chamber results showed that the Peace Bridge traffic was clearly a source of acrolein, with an average concentration of 0.26 microg/m3 at a site 152.4 m downwind (northeast) of the plaza. The OSHA cartridges proved to be too insensitive to determine ambient acrolein concentrations. The DNSH passive samplers returned concentrations near the limit of detection; hence the values were a little higher and less consistent than those in the mist chamber results. The optimized mist chamber method was then applied to determine atmospheric acrolein concentrations at three sites in northern California: a site chosen to reflect the hemispheric background, a region dominated by biogenic sources, and an urban environment. The resulting average acrolein concentrations were 0.056, 0.089, and 0.290 microg/m3, respectively, and the limit of detection was 0.012 microg/m3 The consistency of the replicate samples obtained in the field was good, with the relative standard deviations (RSDs) ranging from 19% at the hemispheric background site to 3% at the urban site. The advantage of the current mist chamber method is that it can determine ambient acrolein concentrations over short time periods with enough sensitivity to be effective even in relatively "clean" environments. This allows for the determination of temporal patterns related to acrolein concentrations, such as diurnal cycles of reaction kinetics. The main disadvantages of the method are that it is laborious and time-consuming and requires specialized equipment that makes it difficult to utilize for routine monitoring of acrolein.

A multidisciplinary investigation of a polycythemia vera cancer cluster of unknown origin.

Cancer cluster investigations rarely receive significant public health resource allocations due to numerous inherent challenges and the limited success of past efforts. In 2008, a cluster of polycythemia vera, a rare blood cancer with unknown etiology, was identified in northeast Pennsylvania. A multidisciplinary group of federal and state agencies, academic institutions, and local healthcare providers subsequently developed a multifaceted research portfolio designed to better understand the cause of the cluster. This research agenda represents a unique and important opportunity to demonstrate that cancer cluster investigations can produce desirable public health and scientific outcomes when necessary resources are available.

Use of molecular testing to identify a cluster of patients with polycythemia vera in eastern Pennsylvania.

BACKGROUND: The role of the environment in the origin of polycythemia vera has not been well documented. Recently, molecular diagnostic tools have been developed to facilitate the diagnosis of polycythemia vera. A cluster of patients with polycythemia vera was suspected in three countries in eastern Pennsylvania where there have long been a concern about environment hazards. METHODS: Rigorous clinical criteria and JAK2 617V>F testing were used to confirm the diagnosis of polycythemia vera in patients in this area. Participants included cases of polycythemia vera from the 2001 to 2005 state cancer registry as well as self- and physician-referred cases. FINDING: A diagnosis of polycythemia vera was confirmed in 53% of 62 participants using WHO criteria, which includes JAK2 617V>F testing. A statistically significant cluster of cases (P < 0.001) was identified where the incidence of polycythemia vera was 4.3 times that of the rest of the study area. The area of the cluster contained numerous sources of hazardous material including waste-coal power plants and U.S. Environmental Protection Agency Superfund sites. INTERPRETATION: The diagnosis of polycythemia vera based solely on clinical criteria is frequently erroneous, suggesting that our prior knowledge of the epidemiology of this disease might be inaccurate. The JAK2 617V>F mutational analysis provides diagnostic clarity and permitted the confirmation of a cluster of polycythemia vera cases not identified by traditional clinical and pathologic diagnostic criteria. The close proximity of this cluster to known areas of hazardous material exposure raises concern that such environmental factors might play a role in the origin of polycythemia vera.

Origin, occurrence, and source emission rate of acrolein in residential indoor air.

Acrolein, a volatile, unsaturated aldehyde, is a known respiratory toxicant and one of the 188 most hazardous air pollutants identified by the U.S. EPA. A newly developed analytical method was used to determine residential indoor air concentrations of acrolein and other volatile aldehydes in nine homes located in three California counties (Los Angeles, Placer, Yolo). Average indoor air concentrations of acrolein were an order of magnitude higher than outdoor concentrations at the same time. All homes showed similar diurnal patterns in indoor air concentrations, with acrolein levels in evening samples up to 2.5 times higherthan morning samples. These increases were strongly correlated with temperature and cooking events, and homes with frequent, regular cooking activity had the highest baseline (morning) acrolein levels. High acrolein concentrations were also found in newly built, uninhabited homes and in emissions from lumber commonly used in home construction, suggesting indoor contributions from off-gassing and/or secondary formation. The results provide strong evidence that human exposure to acrolein is dominated by indoor air with little contribution from ambient outdoor air.

A sensitive method for the quantification of acrolein and other volatile carbonyls in ambient air.

Acrolein, an unsaturated aldehyde found in both indoor and outdoor air, is considered one of the greatest noncancer health risks of all organic air pollutants. Current methods for determining acrolein often employ sorbent-filled cartridges containing a carbonyl derivatizing agent (e.g., dinitrophenylhydrazine). These methods are of limited use for unsaturated compounds due to the formation of unstable derivatives, coelution of similar compounds, long sample collection times, and ozone interferences that result in poor sensitivity, selectivity, and reproducibility. The goal of this research was to develop an analytical method for determining ppt concentrations of acrolein and other carbonyls in air with short sampling times (10 min). The method uses a mist chamber to collect carbonyls by forming water-soluble carbonyl-bisulfite adducts. The carbonyls are then liberated from the bisulfite, derivatized, and quantified by gas chromatography/electron capture negative ionization mass spectrometry. The method was applied to determine atmospheric acrolein concentrations at three sites in northern California reflecting hemispheric background concentrations, biogenic-dominated regions, and urban environments. The resulting acrolein concentrations were 0.056, 0.089, and 0.29 microg/m3, respectively, which are all above the EPA Reference Concentration of 0.02 microg/m3. The minimum detection limit of 0.012 microg/m3 is below that of other published methods. Methacrolein, methyl vinyl ketone, crotonaldehyde, glyoxal, methyl glyoxal, and benzaldehyde were also quantified.