Paul Switzer

All Publications

• Reassessing the relationship between ozone and short-term mortality in US urban communities INHALATION TOXICOLOGY Smith, R. L., Xu, B., Switzer, P. 2009; 21: 37-61

  Abstract

  Time-series studies that use daily mortality and ambient ozone concentrations exhibit estimates of ozone effects that are variable across cities. We investigate this intercity variability, as well as the sensitivity of the ozone- mortality associations to modeling assumptions and choice of daily ozone metric, based on reanalysis of data from the National Morbidity, Mortality and Air Pollution Study (NMMAPS). Previous work from NMMAPS reported a statistically significant association between ambient 24-h ozone and short-term mortality when averaged across 98 U.S. cities. Separation of ozone health associations from effects due to weather and co-pollutants is central to their interpretation. We examined the sensitivity of city-specific ozone-mortality estimates to adjustments for confounders and effect modifiers, showing substantial sensitivity. We examined ozone-mortality associations in different concentration ranges, finding a larger incremental effect in higher ranges, but also larger uncertainty. Alternative ozone exposure metrics defined by maximum 8-h averages or 1-h maxima show different ozone-mortality associations that cannot be explained by simple scaling relationships. The emphasis in earlier studies based on NMMAPS has been on the reporting of "national" effects, together with prediction intervals that suggest that these national values are precisely estimated. Our view is that ozone-mortality associations, based on time-series epidemiologic analyses of daily data from multiple cities, reveal still-unexplained inconsistencies and show sensitivity to modeling choices and data selection that contribute to serious uncertainties when epidemiological results are used to discern the nature and magnitude of possible ozone-mortality relationships or are applied to risk assessment.

  View details for DOI 10.1080/08958370903161612

  View details for Web of Science ID 000270271200002

  View details for PubMedID 19731973

• Observed 1970-2005 Cooling of Summer Daytime Temperatures in Coastal California JOURNAL OF CLIMATE Lebassi, B., Gonzalez, J., Fabris, D., Maurer, E., Miller, N., Milesi, C., Switzer, P., Bornstein, R. 2009; 22 (13): 3558-3573

  View details for DOI 10.1175/2008JCLI2111.1

  View details for Web of Science ID 000268127300003

• Outdoor air pollution in close proximity to a continuous point source ATMOSPHERIC ENVIRONMENT Klepeis, N. E., Gabel, E. B., Ott, W. R., Switzer, P. 2009; 43 (20): 3155-3167

  View details for DOI 10.1016/j.atmosenv.2009.03.056

  View details for Web of Science ID 000267117100001

• Effect of interior door position on room-to-room differences in residential pollutant concentrations after short-term releases ATMOSPHERIC ENVIRONMENT Ferro, A. R., Klepeis, N. E., Ott, W. R., Nazaroff, W. W., Hildemann, L. M., Switzer, P. 2009; 43 (3): 706-714

  View details for DOI 10.1016/j.atmosenv.2008.09.032

  View details for Web of Science ID 000262737900027

• Estimating disease prevalence using census data EPIDEMIOLOGY AND INFECTION Choy, M., Switzer, P., de Martel, C., Parsonnet, J. 2008; 136 (9): 1253-1260

  Abstract

  We describe a method of working on publicly available data to estimate disease prevalence in small geographic areas using Helicobacter pylori as a model infection. Using data from the Third National Health and Nutrition Examination Survey, risk parameters for H. pylori infection were obtained by logistic regression and validated by predicting 737.5 infections in an independent cohort with 736 observed infections. The prevalence of H. pylori infection in the San Francisco Bay Area was estimated with the probabilities obtained from a predictive logistic model, using risk parameters with individual-level 1990 U.S. Census data as input. Predicted H. pylori prevalence was also compared to gastric cancer incidence obtained from the Northern California Cancer Center and showed a positive correlation with gastric cancer incidence (P<0.001, R2=0.87), and no statistically significant association with other malignancies. By exclusively using publicly available data, these methods may be applied to selected conditions with strong demographic predictors.

  View details for DOI 10.1017/S0950268807009752

  View details for Web of Science ID 000259332400014

  View details for PubMedID 18047747

• Air change rates of motor vehicles and in-vehicle pollutant concentrations from secondhand smoke JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY Ott, W., Klepeis, N., Switzer, P. 2008; 18 (3): 312-325

  Abstract

  The air change rates of motor vehicles are relevant to the sheltering effect from air pollutants entering from outside a vehicle and also to the interior concentrations from any sources inside its passenger compartment. We made more than 100 air change rate measurements on four motor vehicles under moving and stationary conditions; we also measured the carbon monoxide (CO) and fine particle (PM(2.5)) decay rates from 14 cigarettes smoked inside the vehicle. With the vehicle stationary and the fan off, the ventilation rate in air changes per hour (ACH) was less than 1 h(-1) with the windows closed and increased to 6.5 h(-1) with one window fully opened. The vehicle speed, window position, ventilation system, and air conditioner setting was found to affect the ACH. For closed windows and passive ventilation (fan off and no recirculation), the ACH was linearly related to the vehicle speed over the range from 15 to 72 mph (25 to 116 km h(-1)). With a vehicle moving, windows closed, and the ventilation system off (or the air conditioner set to AC Max), the ACH was less than 6.6 h(-1) for speeds ranging from 20 to 72 mph (32 to 116 km h(-1)). Opening a single window by 3'' (7.6 cm) increased the ACH by 8-16 times. For the 14 cigarettes smoked in vehicles, the deposition rate k and the air change rate a were correlated, following the equation k=1.3a (R(2)=82%; n=14). With recirculation on (or AC Max) and closed windows, the interior PM(2.5) concentration exceeded 2000 microg m(-3) momentarily for all cigarettes tested, regardless of speed. The concentration time series measured inside the vehicle followed the mathematical solutions of the indoor mass balance model, and the 24-h average personal exposure to PM(2.5) could exceed 35 microg m(-3) for just two cigarettes smoked inside the vehicle.

  View details for DOI 10.1038/sj.jes.7500601

  View details for Web of Science ID 000255057100010

  View details for PubMedID 17637707

• Error analysis for the evaluation of model performance: rainfall-runoff event summary variables HYDROLOGICAL PROCESSES Pebesma, E. J., Switzer, P., Loague, K. 2007; 21 (22): 3009-3024

  View details for DOI 10.1002/hyp.6529

  View details for Web of Science ID 000250662900004

• Real-time measurement of outdoor tobacco smoke particles JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Klepeis, N. E., Ott, W. R., Switzer, P. 2007; 57 (5): 522-534

  Abstract

  The current lack of empirical data on outdoor tobacco smoke (OTS) levels impedes OTS exposure and risk assessments. We sought to measure peak and time-averaged OTS concentrations in common outdoor settings near smokers and to explore the determinants of time-varying OTS levels, including the effects of source proximity and wind. Using five types of real-time airborne particle monitoring devices, we obtained more than 8000 min worth of continuous monitoring data, during which there were measurable OTS levels. Measurement intervals ranged from 2 sec to 1 min for the different instruments. We monitored OTS levels during 15 on-site visits to 10 outdoor public places where active cigar and cigarette smokers were present, including parks, sidewalk cafés, and restaurant and pub patios. For three of the visits and during 4 additional days of monitoring outdoors and indoors at a private residence, we controlled smoking activity at precise distances from monitored positions. The overall average OTS respirable particle concentration for the surveys of public places during smoking was approximately 30 microg m(-3). OTS exhibited sharp spikes in particle mass concentration during smoking that sometimes exceeded 1000 microg m(-3) at distances within 0.5 m of the source. Some average concentrations over the duration of a cigarette and within 0.5 m exceeded 200 microg m(-3), with some average downwind levels exceeding 500 microg m(-3). OTS levels in a constant upwind direction from an active cigarette source were nearly zero. OTS levels also approached zero at distances greater than approximately 2 m from a single cigarette. During periods of active smoking, peak and average OTS levels near smokers rivaled indoor tobacco smoke concentrations. However, OTS levels dropped almost instantly after smoking activity ceased. Based on our results, it is possible for OTS to present a nuisance or hazard under certain conditions of wind and smoker proximity.

  View details for DOI 10.3155/1047-3289.57.5.522

  View details for Web of Science ID 000246257100001

  View details for PubMedID 17518219

• Stochastic space-time regional rainfall modeling adapted to historical rain gauge data WATER RESOURCES RESEARCH Zhang, Z., Switzer, P. 2007; 43 (3)

  View details for DOI 10.1029/2005WR004654

  View details for Web of Science ID 000245557000002

• Evaluating detection of an inhalational anthrax outbreak EMERGING INFECTIOUS DISEASES Buckeridge, D. L., Owens, D. K., Switzer, P., Frank, J., Musen, M. A. 2006; 12 (12): 1942-1949

  Abstract

  Timely detection of an inhalational anthrax outbreak is critical for clinical and public health management. Syndromic surveillance has received considerable investment, but little is known about how it will perform relative to routine clinical case finding for detection of an inhalational anthrax outbreak. We conducted a simulation study to compare clinical case finding with syndromic surveillance for detection of an outbreak of inhalational anthrax. After simulated release of 1 kg of anthrax spores, the proportion of outbreaks detected first by syndromic surveillance was 0.59 at a specificity of 0.9 and 0.28 at a specificity of 0.975. The mean detection benefit of syndromic surveillance was 1.0 day at a specificity of 0.9 and 0.32 days at a specificity of 0.975. When syndromic surveillance was sufficiently sensitive to detect a substantial proportion of outbreaks before clinical case finding, it generated frequent false alarms.

  View details for Web of Science ID 000242301900022

  View details for PubMedID 17326949

  View details for PubMedCentralID PMC3291344

• Filter-based classification of training image patterns for spatial simulation MATHEMATICAL GEOLOGY Zhang, T., Switzer, P., Journel, A. 2006; 38 (1): 63-80

  View details for DOI 10.1007/s11004-005-9004-x

  View details for Web of Science ID 000238343600005

• An evaluation model for syndromic surveillance: assessing the performance of a temporal algorithm. MMWR. Morbidity and mortality weekly report Buckeridge, D. L., Switzer, P., Owens, D., SIEGRIST, D., Pavlin, J., Musen, M. 2005; 54: 109-115

  Abstract

  Syndromic surveillance offers the potential to rapidly detect outbreaks resulting from terrorism. Despite considerable experience with implementing syndromic surveillance, limited evidence exists to describe the performance of syndromic surveillance systems in detecting outbreaks.To describe a model for simulating cases that might result from exposure to inhalational anthrax and then use the model to evaluate the ability of syndromic surveillance to detect an outbreak of inhalational anthrax after an aerosol release.Disease progression and health-care use were simulated for persons infected with anthrax. Simulated cases were then superimposed on authentic surveillance data to create test data sets. A temporal outbreak detection algorithm was applied to each test data set, and sensitivity and timeliness of outbreak detection were calculated by using syndromic surveillance.The earliest detection using a temporal algorithm was 2 days after a release. Earlier detection tended to occur when more persons were infected, and performance worsened as the proportion of persons seeking care in the prodromal disease state declined. A shorter median incubation state led to earlier detection, as soon as 1 day after release when the incubation state was < or =5 days.Syndromic surveillance of a respiratory syndrome using a temporal detection algorithm tended to detect an anthrax attack within 3-4 days after exposure if >10,000 persons were infected. The performance of surveillance (i.e., timeliness and sensitivity) worsened as the number of persons infected decreased.

  View details for PubMedID 16177701

• Error analysis for the evaluation of model performance: rainfall-runoff event time series data HYDROLOGICAL PROCESSES Pebesma, E. J., Switzer, P., Loague, K. 2005; 19 (8): 1529-1548

  View details for DOI 10.1002/hyp.5587

  View details for Web of Science ID 000229232800001

• Merging prior structural interpretation and local data: The Bayes updating of multiple-point statistics Annual Conference of the International-Association-for-Mathematical-Geology Zhang, T., Switzer, P., Journel, A. YORK UNIV. 2005: 615–620

  View details for Web of Science ID 000233264200103

• Sequential conditional simulation using classification of local training patterns 7th International Geostatistics Congress Zhang, T., Switzer, P., Journel, A. SPRINGER. 2005: 265–273

  View details for Web of Science ID 000234961400027

• Mortality displacement and distributed lag models INHALATION TOXICOLOGY Roberts, S., Switzer, P. 2004; 16 (14): 879-888

  Abstract

  Numerous time-series studies have investigated the association between daily mortality and daily ambient particulate air pollution concentrations (PM). The consensus from these studies is that increases in PM are associated with increases in daily mortality. However, it may be that increases in PM only hasten the deaths of individuals in a small, frail subset of the population whose longevity is short even in the absence of particulate air pollution. This hypothesis has been termed mortality displacement or harvesting. Distributed lag models (DLM) have been used to explore mortality effects of air pollution that are spread over multiple days, and DLM coefficients have been proposed as indicators of mortality displacement. We investigate statistical properties of DLM coefficients in the context of mortality displacement using simulation studies with frail population models. Our simulations use actual PM time series, as well as actual weather time series included as confounders. Our simulations show that DLM coefficients can have large bias when the mean lifetime of individuals in the frail subset of the population is more than a few weeks, and that the magnitude of this bias increases as the mean lifetime of individuals in the frail subset of the population increases. We conclude that DLM coefficients may be misleading as an indicator of mortality displacement, in the context of the frail population models that we explored.

  View details for DOI 10.1080/08958370490519598

  View details for Web of Science ID 000225159600002

  View details for PubMedID 15764475

• Estimation of geological attributes from a well log: An application of hidden Markov chains MATHEMATICAL GEOLOGY Eidsvik, J., Mukerji, T., Switzer, P. 2004; 36 (3): 379-397

  View details for Web of Science ID 000221531400006

• Analytical solutions to compartmental indoor air quality models with application to environmental tobacco smoke concentrations measured in a house JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Ott, W. R., Klepeis, N. E., Switzer, P. 2003; 53 (8): 918-936

  Abstract

  This paper derives the analytical solutions to multi-compartment indoor air quality models for predicting indoor air pollutant concentrations in the home and evaluates the solutions using experimental measurements in the rooms of a single-story residence. The model uses Laplace transform methods to solve the mass balance equations for two interconnected compartments, obtaining analytical solutions that can be applied without a computer. Environmental tobacco smoke (ETS) sources such as the cigarette typically emit pollutants for relatively short times (7-11 min) and are represented mathematically by a "rectangular" source emission time function, or approximated by a short-duration source called an "impulse" time function. Other time-varying indoor sources also can be represented by Laplace transforms. The two-compartment model is more complicated than the single-compartment model and has more parameters, including the cigarette or combustion source emission rate as a function of time, room volumes, compartmental air change rates, and interzonal air flow factors expressed as dimensionless ratios. This paper provides analytical solutions for the impulse, step (Heaviside), and rectangular source emission time functions. It evaluates the indoor model in an unoccupied two-bedroom home using cigars and cigarettes as sources with continuous measurements of carbon monoxide (CO), respirable suspended particles (RSP), and particulate polycyclic aromatic hydrocarbons (PPAH). Fine particle mass concentrations (RSP or PM3.5) are measured using real-time monitors. In our experiments, simultaneous measurements of concentrations at three heights in a bedroom confirm an important assumption of the model-spatial uniformity of mixing. The parameter values of the two-compartment model were obtained using a "grid search" optimization method, and the predicted solutions agreed well with the measured concentration time series in the rooms of the home. The door and window positions in each room had considerable effect on the pollutant concentrations observed in the home. Because of the small volumes and low air change rates of most homes, indoor pollutant concentrations from smoking activity in a home can be very high and can persist at measurable levels indoors for many hours.

  View details for Web of Science ID 000184554900002

  View details for PubMedID 12943312

• An analytic framework fo space-time aberrancy detection in public health surveillance data. AMIA ... Annual Symposium proceedings / AMIA Symposium. AMIA Symposium Buckeridge, D. L., Musen, M. A., Switzer, P., Crubézy, M. 2003: 120-124

  Abstract

  Public health surveillance is changing in response to concerns about bioterrorism, which have increased the pressure for early detection of epidemics. Rapid detection necessitates following multiple non-specific indicators and accounting for spatial structure. No single analytic method can meet all of these requirements for all data sources and all surveillance goals. Analytic methods must be selected and configured to meet a surveillance goal, but there are no uniform criteria to guide the selection and configuration process. In this paper, we describe work towards the development of an analytic framework for space-time aberrancy detection in public health surveillance data. The framework decomposes surveillance analysis into sub-tasks and identifies knowledge that can facilitate selection of methods to accomplish sub-tasks.

  View details for PubMedID 14728146

• Graphical assessment of dependence: Is a picture worth 100 tests? AMERICAN STATISTICIAN Fisher, N. I., Switzer, P. 2001; 55 (3): 233-239

  View details for Web of Science ID 000170299300013

• The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY Klepeis, N. E., Nelson, W. C., Ott, W. R., Robinson, J. P., Tsang, A. M., Switzer, P., Behar, J. V., Hern, S. C., Engelmann, W. H. 2001; 11 (3): 231-252

  Abstract

  Because human activities impact the timing, location, and degree of pollutant exposure, they play a key role in explaining exposure variation. This fact has motivated the collection of activity pattern data for their specific use in exposure assessments. The largest of these recent efforts is the National Human Activity Pattern Survey (NHAPS), a 2-year probability-based telephone survey (n=9386) of exposure-related human activities in the United States (U.S.) sponsored by the U.S. Environmental Protection Agency (EPA). The primary purpose of NHAPS was to provide comprehensive and current exposure information over broad geographical and temporal scales, particularly for use in probabilistic population exposure models. NHAPS was conducted on a virtually daily basis from late September 1992 through September 1994 by the University of Maryland's Survey Research Center using a computer-assisted telephone interview instrument (CATI) to collect 24-h retrospective diaries and answers to a number of personal and exposure-related questions from each respondent. The resulting diary records contain beginning and ending times for each distinct combination of location and activity occurring on the diary day (i.e., each microenvironment). Between 340 and 1713 respondents of all ages were interviewed in each of the 10 EPA regions across the 48 contiguous states. Interviews were completed in 63% of the households contacted. NHAPS respondents reported spending an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles. These proportions are fairly constant across the various regions of the U.S. and Canada and for the California population between the late 1980s, when the California Air Resources Board (CARB) sponsored a state-wide activity pattern study, and the mid-1990s, when NHAPS was conducted. However, the number of people exposed to environmental tobacco smoke (ETS) in California seems to have decreased over the same time period, where exposure is determined by the reported time spent with a smoker. In both California and the entire nation, the most time spent exposed to ETS was reported to take place in residential locations.

  View details for Web of Science ID 000170077100008

  View details for PubMedID 11477521

• Untitled JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Switzer, P. 2001; 51 (3): 322-323

  View details for Web of Science ID 000167521500002

• Multiple simulation of spatial fields 4th International Symposium on Spatial Accuracy Assessment in Natural Resources and Environmental Sciences Switzer, P. DELFT UNIV PRESS DUP SCI. 2000: 629–635

  View details for Web of Science ID 000177422100095

• Investigations of the proximity effect for pollutants in the indoor environment JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY McBride, S. J., Ferro, A. R., Ott, W. R., Switzer, P., Hildemann, L. M. 1999; 9 (6): 602-621

  Abstract

  More than a dozen indoor air quality studies have reported a large discrepancy between concentrations measured by stationary indoor monitors (SIMs) and personal exposure monitors (PEMs). One possible cause of this discrepancy is a source proximity effect, in which pollutant sources close to the respondent cause elevated and highly variable exposures. This paper describes three sets of experiments in a home using real-time measurements to characterize and quantify the proximity effect relative to a fixed distant location analogous to a SIM. In the first set of experiments, using sulfur hexafluoride (SF6) as a continuously emitting tracer pollutant from a point source, measurements of pollutant concentrations were made at different distances from the source under different air exchange rates and source strengths. A second set of experiments used a continuous point source of carbon monoxide (CO) tracer pollutant and an array of high time resolution monitors to collect simultaneous concentration readings at different locations in the room. A third set of experiments measured particle count density and particle-bound polycyclic aromatic hydrocarbon (PAH) concentrations emitted from a continuous particle point source (an incense stick) using two particle counters and two PAH monitors, and included human activity periods both before and during the source emission period. Results from the SF6 and CO experiments show that while the source is emitting, a source proximity effect can be seen in the increases in the mean and median and in the variability of concentrations closest to the source, even at a distance of 2.0 m from the source under certain settings of air exchange rate and source strength. CO concentrations at locations near the source were found to be higher and more variable than the predictions of the mass balance model. For particles emitted from the incense source, a source proximity effect was evident for the fine particle sizes (0.3 to 2.5 microm) and particle-bound PAH up to at least 1.0 m from the source. Analysis of spatial and temporal patterns in the data for the three tracer pollutants reveal marked transient elevations of concentrations as seen by the monitor, referred to as "microplumes," particularly at locations close to the source. Mixing patterns in the room show complex patterns and directional effects, as evidenced by the variable intensity of the microplume activity at different locations. By characterizing the spatial and temporal variability of pollutant concentrations in the home, the proximity effect can be quantified, leading to improved indoor monitoring designs and models of human exposure to air pollutants.

  View details for Web of Science ID 000086103600008

  View details for PubMedID 10638846

• Human exposure to particles due to indoor cleaning activities 7th International Air Pollution Conference Ferro, A., Hildemann, L. M., McBride, S. J., Ott, W., Switzer, P. WIT PRESS. 1999: 487–496

  View details for Web of Science ID 000083991000047

• Differential exposure misclassification in case control studies of environmental tobacco smoke and lung cancer JOURNAL OF CLINICAL EPIDEMIOLOGY Levois, M., Switzer, P. 1998; 51 (1): 37-54

  Abstract

  We review some of the literature on the effects of exposure misclassification on the statistical analysis of case-control studies. In particular, we focus on evidence for exposure misclassification which may be different for cases and controls in studies of environmental tobacco smoke (ETS). For example, such misclassification could induce relative risk estimates below unity for low exposure which appears to be the case in U.S. lung cancer and ETS studies. We describe procedures for systematically examining the sensitivity of dose-response statistics on exposure misclassification. The procedures demonstrate how p-values for the null hypothesis of no dose-response trend could be adjusted to account for exposure misclassification. The adjustment procedures were applied to an example based on a recently published large study of ETS and lung cancer in which a p-value for trend was reported as 0.03. In this example it is seen that modest differential exposure misclassification can induce substantial increases in the actual p-value, changing what appears to be statistically significant to decidedly nonsignificant.

  View details for Web of Science ID 000071231700005

  View details for PubMedID 9467633

• Particle concentrations inside a tavern before and after prohibition of smoking: Evaluating the performance of an indoor air quality model - Response JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Ott, W., Switzer, P. 1997; 47 (4): 452-454

  View details for Web of Science ID A1997WU26400005

• Particle concentrations inside a tavern before and after prohibition of smoking: Evaluating the performance of an indoor air quality model JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Ott, W., Switzer, P., Robinson, J. 1996; 46 (12): 1120-1134

  View details for Web of Science ID A1996VY40900006

• A multiple-smoker model for predicting indoor air quality in public lounges ENVIRONMENTAL SCIENCE & TECHNOLOGY Klepeis, N. E., Ott, W. R., Switzer, P. 1996; 30 (9): 2813-2820

  View details for Web of Science ID A1996VE88300033

• Daily exposure to environmental tobacco smoke: Smokers vs nonsmokers in California AMERICAN JOURNAL OF PUBLIC HEALTH Robinson, J. P., Switzer, P., Ott, W. 1996; 86 (9): 1303-1305

  Abstract

  This study examined the differences in environmental tobacco smoke exposure between smokers and non-smokers.A probability sample of 1579 California adults completed a 1-day time diary of a full day's activities in which they reported whether any smoker was present during each activity.Some 61% of respondents reported at least some environmental tobacco smoke exposure in these diary accounts (for an average of up to 5 hours per day), and potential exposure rose monotonically with number of cigarettes actively smoked. Heaviest smokers reported about four times as much such exposure as nonsmokers.Because smokers lead life-styles that expose them to far higher levels of environmental tobacco smoke exposure, that factor needs to be controlled in studies estimating the effects of active smoking.

  View details for Web of Science ID A1996VH21200020

  View details for PubMedID 8806385

• Ambient sulfate concentrations near grand canyon as a function of fluctuating loads at the Mohave Power Project: An exploratory analysis of an atmospheric experiment ATMOSPHERIC ENVIRONMENT Switzer, P., Enger, L., HOFFER, T. E., Koracin, D., White, W. H. 1996; 30 (14): 2551-2564

  View details for Web of Science ID A1996UK36300009

• Time trend estimation for a geographic region JOURNAL OF THE AMERICAN STATISTICAL ASSOCIATION Solna, K., Switzer, P. 1996; 91 (434): 577-589

  View details for Web of Science ID A1996UP55200027

• SPATIAL INTERPOLATION ERRORS FOR MONITORING DATA JOURNAL OF THE AMERICAN STATISTICAL ASSOCIATION Host, G., Omre, H., Switzer, P. 1995; 90 (431): 853-861

  View details for Web of Science ID A1995RQ57800006

• CARBON-MONOXIDE EXPOSURES INSIDE AN AUTOMOBILE TRAVELING ON AN URBAN ARTERIAL HIGHWAY JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION Ott, W., Switzer, P., Willits, N. 1994; 44 (8): 1010-1018

  Abstract

  Carbon monoxide (CO) exposures were measured inside a motor vehicle during 88 standardized drives on a major urban arterial highway, El Camino Real (traffic volume of 30,500-45,000 vehicles per day), over a 13-1/2 month period. On each trip (lasting between 31 and 61 minutes), the test vehicle drove the same 5.9-mile segment of roadway in both directions, for a total of 11.8 miles, passing through 20 intersections with traffic lights (10 in each direction) in three California cities (Menlo Park, Palo Alto, and Los Altos). Earlier tests showed that the test vehicle was free of CO intrusion. For the 88 trips, the mean CO concentration was 9.8 ppm, with a standard deviation of 5.8 ppm. Of nine covariates that were examined to explain the variability in the mean CO exposures observed on the 88 trips (ambient CO at two fixed stations, atmospheric stability, seasonal trend function, time of day, average surrounding vehicle count, trip duration, proportion of time stopped at lights, and instrument type), a fairly strong seasonal trend was found. A model consisting of only a single measure of traffic volume and a seasonal trend component had substantial predictive power (R2 = 0.68); by contrast, the ambient CO levels, although partially correlated with average exposures, contributed comparatively little predictive power to the model. The CO exposures experienced while drivers waited at the red lights at an intersection ranged from 6.8 to 14.9 ppm and differed considerably from intersection to intersection.(ABSTRACT TRUNCATED AT 250 WORDS)

  View details for Web of Science ID A1994PD11600007

  View details for PubMedID 7921891

• ENVIRONMENTAL TOBACCO-SMOKE AND LUNG-CANCER RISK IN NONSMOKING WOMEN JOURNAL OF THE NATIONAL CANCER INSTITUTE Switzer, P. 1993; 85 (9): 749-750

  View details for Web of Science ID A1993LA67200019

  View details for PubMedID 8478963

• A COMMENT ON THE COEFFICIENT OF DETERMINATION FOR BINARY RESPONSES - COMMENT AMERICAN STATISTICIAN Switzer, P. 1992; 46 (3): 243-243

  View details for Web of Science ID A1992JE81900025

• Averaging time modeling of exposure simulation with application to the El Camino Real vehicle data. Journal of exposure analysis and environmental epidemiology Switzer, P., Ott, W. R., Willits, N. H. 1991; 1 (1): 109-121

  Abstract

  When profiles of activity patterns are used to generate time series of simulated exposure, one typically samples from exposure distributions which are microenvironment-specific to each activity. If the simulation time step is short, then independent sampling at each time step, ignoring autocorrelation, will result in aggregates with too little variability from one simulation to another. Autocorrelation can often be modeled with one or two extra parameters and then used in the simulation. Furthermore, one may substantially reduce computation by generating a single averaged exposure for each activity segment whose distribution depends in a simple way on the activity duration and the modeled autocorrelation. The process is illustrated using the El Camino Real commuting exposure study data of Ott, Switzer, and Willits.

  View details for PubMedID 1726712

• AN ANALYSIS OF HOURLY DEPOSITION DATA CANADIAN JOURNAL OF STATISTICS-REVUE CANADIENNE DE STATISTIQUE Switzer, P. 1988; 16 (1): 39-50

  View details for Web of Science ID A1988P113300004

• A STATISTICAL-METHOD FOR ESTIMATING RATES OF SOIL DEVELOPMENT AND AGES OF GEOLOGIC DEPOSITS - A DESIGN FOR SOIL-CHRONOSEQUENCE STUDIES MATHEMATICAL GEOLOGY Switzer, P., Harden, J. W., MARK, R. K. 1988; 20 (1): 49-61

  View details for Web of Science ID A1988L822800003

• A TRANSFORMATION FOR ORDERING MULTISPECTRAL DATA IN TERMS OF IMAGE QUALITY WITH IMPLICATIONS FOR NOISE REMOVAL IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING Green, A. A., Berman, M., Switzer, P., Craig, M. D. 1988; 26 (1): 65-74

  View details for Web of Science ID A1988L419100009

• ORDERING OF TIME DIFFERENCE DATA FROM MULTISPECTRAL IMAGERY REMOTE SENSING OF ENVIRONMENT Switzer, P., Ingebritsen, S. E. 1986; 20 (1): 85-94

  View details for Web of Science ID A1986D380700005

• PROJECTION PURSUIT - DISCUSSION ANNALS OF STATISTICS Switzer, P. 1985; 13 (2): 515-517

  View details for Web of Science ID A1985AKQ9500014

• VARIABILITY OF ELEMENTAL CONCENTRATIONS IN POWER-PLANT ASH ENVIRONMENTAL SCIENCE & TECHNOLOGY Holcombe, L. J., Eynon, B. P., Switzer, P. 1985; 19 (7): 615-620

  View details for Web of Science ID A1985AKW9000009

  View details for PubMedID 22148304

• CHI-PLOTS FOR ASSESSING DEPENDENCE BIOMETRIKA Fisher, N. I., Switzer, P. 1985; 72 (2): 253-265

  View details for Web of Science ID A1985AMZ4700003

• THE EFFECTS OF ADDITIVE RADIANCE TERMS ON RATIOS OF LANDSAT DATA PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING KOWALIK, W. S., Lyon, R. J., Switzer, P. 1983; 49 (5): 659-669

  View details for Web of Science ID A1983QQ82900006

• NONPARAMETRIC GEOSTATISTICS - HENLEY,S (Book Review) JOURNAL OF THE AMERICAN STATISTICAL ASSOCIATION Book Review Authored by: Switzer, P. 1983; 78 (382): 510-510

  View details for Web of Science ID A1983QU74700079

• A PRIOR PROBABILITY METHOD FOR SMOOTHING DISCRIMINANT-ANALYSIS CLASSIFICATION MAPS JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR MATHEMATICAL GEOLOGY Switzer, P., KOWALIK, W. S., Lyon, R. J. 1982; 14 (5): 433-444

  View details for Web of Science ID A1982PG37500004

• ESTIMATION OF ATMOSPHERIC PATH-RADIANCE BY THE COVARIANCE-MATRIX METHOD PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING Switzer, P., KOWALIK, W. S., Lyon, R. J. 1981; 47 (10): 1469-1476

  View details for Web of Science ID A1981MK62200004

• SOME CHALLENGING APPLICATIONS OF STATISTICAL-METHODS IN THE EARTH SCIENCES JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR MATHEMATICAL GEOLOGY Switzer, P. 1980; 12 (5): 417-423

  View details for Web of Science ID A1980KR16800002

• EXTENSIONS OF LINEAR DISCRIMINANT-ANALYSIS FOR STATISTICAL CLASSIFICATION OF REMOTELY SENSED SATELLITE IMAGERY JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR MATHEMATICAL GEOLOGY Switzer, P. 1980; 12 (4): 367-376

  View details for Web of Science ID A1980KQ85500006

• RESOLVING THE PERCENTAGE OF COMPONENT TERRAINS WITHIN SINGLE RESOLUTION ELEMENTS PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING Marsh, S. E., Switzer, P., KOWALIK, W. S. 1980; 46 (8): 1079-1086

  View details for Web of Science ID A1980KD60000006

• STATISTICAL CONSIDERATIONS IN NETWORK DESIGN WATER RESOURCES RESEARCH Switzer, P. 1979; 15 (6): 1712-1716

  View details for Web of Science ID A1979JC38700065

• STATISTICAL-ANALYSIS OF SPATIAL PATTERN - BARTLETT,MS (Book Review) JOURNAL OF THE AMERICAN STATISTICAL ASSOCIATION Book Review Authored by: Switzer, P. 1978; 73 (363): 684-684

  View details for Web of Science ID A1978FQ99600055

• DISTRIBUTION OF REDSHIFTS OF QUASARS AND RELATED OBJECTS ASTROPHYSICAL JOURNAL Knight, J. W., Sturrock, P. A., Switzer, P. 1976; 203 (2): 286-290

  View details for Web of Science ID A1976BG60600002

• GEOMETRICAL MEASURES OF SMOOTHNESS OF RANDOM FUNCTIONS JOURNAL OF APPLIED PROBABILITY Switzer, P. 1976; 13 (1): 86-95

  View details for Web of Science ID A1976BS38500010

• CONFIDENCE PROCEDURES FOR 2-SAMPLE PROBLEMS BIOMETRIKA Switzer, P. 1976; 63 (1): 13-25

  View details for Web of Science ID A1976BL81800002

• MODEL RELATING UNDETECTED GEOMAGNETIC POLARITY INTERVALS TO OBSERVED RATE OF REVERSALS JOURNAL OF GEOPHYSICAL RESEARCH TACIER, J. D., Switzer, P., Cox, A. 1975; 80 (32): 4446-4448

  View details for Web of Science ID A1975AX55800006

• Karyometry in the estimation of nuclear population in pulmonary carcinomas. Journal of the National Cancer Institute Switzer, P., GERSTL, B., Greenspoon, J. 1974; 52 (6): 1699-1704

  View details for PubMedID 4365386

• MORPHOMETRIC STUDY OF PULMONARY CANCER CANCER RESEARCH GERSTL, B., Switzer, P., Yesner, R. 1974; 34 (1): 248-254

  View details for Web of Science ID A1974R745900039

  View details for PubMedID 4588547

• KARYOMETRY IN ESTIMATION OF NUCLEAR POPULATION IN PULMONARY CARCINOMAS JOURNAL OF THE NATIONAL CANCER INSTITUTE Switzer, P., GERSTL, B., GREENSPO, J. 1974; 52 (6): 1699-1704

  View details for Web of Science ID A1974T403000003

  View details for PubMedID 4365386

• PROPOSED SAMPLING CONSTANT FOR USE IN GEOCHEMICAL ANALYSIS TALANTA INGAMELL, C. O., Switzer, P. 1973; 20 (6): 547-568

  View details for Web of Science ID A1973P598800005

• STATISTICAL ANALYSIS OF GEOLOGICAL DATA .2. KOCH,GS AND LINK,RF (Book Review) JOURNAL OF THE AMERICAN STATISTICAL ASSOCIATION Book Review Authored by: Switzer, P. 1973; 68 (341): 243-243

  View details for Web of Science ID A1973P259500057

• PERIODICITY IN RADIOFREQUENCY SPECTRUM OF PULSAR CP 0328 ASTROPHYSICAL JOURNAL Sturrock, P. A., Switzer, P., Vallee, J., Antiochos, S. 1972; 171 (1): L27-?

  View details for Web of Science ID A1972L469800006

• Possible high-frequency modulation of light from the Crab pulsar. Nature Sturrock, P. A., Bracewell, R. N., Switzer, P. 1971; 229 (5281): 186-187

  View details for PubMedID 16059140

• POSSIBLE HIGH-FREQUENCY MODULATION OF LIGHT FROM CRAB PULSAR NATURE Sturrock, P. A., BRACEWEL, R. N., Switzer, P. 1971; 229 (5281): 186-?

  View details for Web of Science ID A1971I254100030

• LONGITUDE DISTRIBUTION OF SOLAR FLARES SOLAR PHYSICS Fung, P. C., Sturrock, P. A., Switzer, P., VANHOVEN, G. 1971; 18 (1): 90-?

  View details for Web of Science ID A1971J642200013