Wayne Ott

• PhD
• Stanford University at Stanford University

Low-cost monitors make it possible now for the first time to collect long-term (months to years) measurements of potential indoor exposure to fine particles. Indoor exposure is due to two sources: particles infiltrating from outdoors and those generated by indoor activities. Calculating the relative contribution of each source requires identifying...

Low-cost monitors make it possible now for the first time to collect long-term (months to years) measurements of potential indoor exposure to fine particles. Indoor exposure is due to two sources: particles infiltrating from outdoors and those generated by indoor activities. Calculating the relative contribution of each source requires identifying...

The widespread legalization of recreational marijuana raises growing concerns about exposure to secondhand marijuana smoke. An important location for marijuana smoking is the home, but few measurements of air pollutant concentrations in the home are available for a marijuana joint fully smoked in one of its rooms. We used research grade calibrated...

The widespread legalization of recreational marijuana raises growing concerns about exposure to secondhand marijuana smoke. An important location for marijuana smoking is the home, but few measurements of air pollutant concentrations in the home are available for a marijuana joint fully smoked in one of its rooms. We used research grade calibrated...

We conducted 35 experiments for spatial measurement of marijuana aerosols in a current smoker's residential spaces. Fine particulate matter (PM2.5) concentrations were measured every second at 1, 2, and 3 m horizontal distances from the smoker who performed prescribed 5-min smoking and vaping activities. In each experiment, five SidePak monitors me...

PM2.5 hourly average measurements from 33 outdoor PurpleAir particle monitors were compared with hourly measurements from 27 nearby US EPA Air Quality System (AQS) stations employing Federal Equivalent Method (FEM) monitors in California over an 18-month (77-week) period. A transparent and reproducible alternative method (ALT) of calculating PM2.5...

We present a new method to estimate the fraction of an aerosol mixture that is volatile, as well as the time required for evaporation from a collecting surface. The method depends on an instrument (the Piezobalance) designed to measure the accumulated mass on a quartz crystal that can also measure the subsequent loss of mass due to evaporation. Com...

A new method for determining the volatility of any aerosol mixture < 2.5 um in diameter is presented. The method employs a Piezobalance modified to record mass loss from the quartz surface. Two examples are explored: vapor from e-cigarettes and marijuana liquids. The volatility fraction was 88% (CI 77-99%) for the e-cigarettes. It was <7% for marij...

Supplementary information for Atmospheric Environment article on Method for Estimating Volatility of Aerosol Mixtures

Eleven states have legalized the sales of recreational marijuana, and California has the largest sales of any state. Cannabis is most often smoked indoors, but few measurements have been made of fine particle mass concentrations produced by secondhand cannabis smoke in indoor settings. We conducted 60 controlled experiments in a 43 m³ room of a res...

A popular method of inhaling marijuana is by heating marijuana liquid (vaping). We study exhaled aerosol within experimental rooms in two inhabited homes and determine peak concentrations, decay and removal rates, and source emissions. These parameters allow a simple exposure model to be developed. The experimental approach was to measure particle...

The widespread legalization of recreational cannabis use raises growing concerns about exposure to secondhand cannabis smoke (SCS). However, few studies are characterizing fine particulate matter (PM2.5) exposure from SCS. Here, we determined PM2.5 calibration factors (CFs) for SCS from four common cannabis consuming methods—glass pipe smoking, joi...

It appears your request is for my chapter "Dispersion and Diffusion of Pollutants" in my textbook "Environmental Statistics and Data Analysis." I regret that I do not have copies of this copyrighted book available, which was published by CRC Press in 1995. It is possible that you will find copies of this book available on line or in libraries.

This paper describes a long-term trend study of passenger exposure to carbon monoxide (CO) inside a vehicle travelling on an arterial highway in Northern California. CO exposure was measured during four field surveys on State Route #82 (El Camino Real) on the San Francisco Peninsula in 1980-1981, 1991-1992, 2001-2002, and 2010-2011. Each field surv...

This paper presents a review of the published scientific literature on air pollution from water pipe smoking. An earlier review by Kumar et al (2015) discusses 11 studies in the literature on water pipe smoking, and this review includes 29 references on this topic. This October 12, 2017, review has seven sections: (1) Introduction, (2) Trends in Ho...

Ultrafine particles (UFP) produced by electric heating of stoves and metal cooking pans, absent food, have been hypothesized to be created from a surface film of semivolatile organic compounds (SVOCs) sorbed from the surrounding air. This study tests that hypothesis by size-resolved measurements extending the lower range of the UFP studied from 10...

The following 5 sections describe: (1) Summary data table for indoor measurements on 73 restaurant visits, (2) Collocation study of the TSI 3007 condensation particle counter (CPC) monitor, (3) Relationship between mean ultrafine particle counts (UFP down to 10 nm) and mean fine particle (FP) PM2.5 mass concentrations indoors in restaurants on the...

A number of studies indicate cooking is a major source of exposure to particulate matter, but few studies have measured indoor air pollution in restaurants, where cooking predominates. We made 73 visits by car to 65 different nonsmoking restaurants in 10 Northern California towns while carrying portable continuous monitors that unobtrusively measur...

Most casinos owned by sovereign American Indian nations allow smoking, even in U.S. states such as California where state laws restrict workplace smoking. Collaborations between casinos and public health workers are needed to promote smoke-free policies that protect workers and patrons from secondhand tobacco smoke (SHS) exposure and risks. Over se...

Real-time particle monitors are essential for accurately estimating exposure to fine particles indoors. However, many such monitors tend to be prohibitively expensive for some applications, such as a tenant or homeowner curious about the quality of the air in their home. A lower cost version (the Dylos Air Quality Monitor) has recently been introdu...

This presentation describes measurements of fine particles (PM-2.5) and ultrafine particles (UFP) in a large California tribal casino before a smoking ban as well as after the smoking ban was implemented. The results show that PM-2.5 mass concentrations decreased by 95% and UFP decreased by 91.5% after the smoking ban was implemented in this casino...

We investigated nicotine levels associated with residents’ complaints of secondhand smoke infiltration in multi-unit housing and the nature of those complaints. Using active (n=5) and passive (n=38) monitors, we measured nicotine in a volunteer sample of 43 nonsmokers’ apartments (condominiums, co-operatives, and rental units) whose residents had s...

Ultrafine particles (UFP) are observed when metal surfaces, such as heating elements in electric appliances, or even empty cooking pans, are heated. The source of the particles has not been identified. We present evidence that particles > 10 nm are not emitted directly from the heating elements or the metal surfaces. Using repeated heating of an el...

Unlabelled: As indoor smoking bans have become widely adopted, some U.S. communities are considering restricting smoking outdoors, creating a need for measurements of air pollution near smokers outdoors. Personal exposure experiments were conducted with four to five participants at six sidewalk bus stops located 1.5-3.3 m from the curb of two heav...

For an actively emitting source such as cooking or smoking, indoor measurements have shown a strong "proximity effect" within 1 m. The significant increase in both the magnitude and variation of concentration near a source is attributable to transient high peaks that occur sporadically-and these "microplumes" cause great uncertainty in estimating p...

Indoor sources can greatly contribute to personal exposure to particulate matter less than 2.5 mm in diameter (PM 2.5). To accurately assess PM 2.5 mass emission factors and concentrations, real-time particle monitors must be calibrated for individual sources. Sixty-six experiments were conducted with a common, real-time laser photometer (TSI SideP...

This report is supplementary material for the article, "Carbon Monoxide Exposures Inside an Automobile Traveling on an Urban Arterial Highway," by W. Ott, P. Switzer, and N. Willits (1994) J. Air & Waste Manag. Assoc. 44:1010-1018. It presents details of a highway CO exposure measurement study of 88 standardized drives on an urban arterial highway...

Few measurements of exposure to secondhand smoke (SHS) in close proximity to a smoker are available. Recent health studies have demonstrated an association between acute (< 2 h) exposures to high concentrations of SHS and increased risk for cardiovascular and respiratory disease. We performed 15 experiments inside naturally-ventilated homes and 16...

Identifying and quantifying secondhand tobacco smoke (SHS) that drifts between multiunit homes is critical for assessing exposure. Twenty-three different gaseous and particulate measurements were collected during controlled emissions from smoked cigarettes and six other common indoor source types in 60 single-room and 13 two-room experiments. We us...

This report analytically derives the solutions to the 2-compartment indoor mass balance model from basic principles. It also provides examples of the concentration time series predicted by the model for a variety of different cases, showing the effect on the resulting time series in two adjacent rooms of different inter-zonal flow rates, different...

h i g h l i g h t s < We monitored 5 multiunit homes with secondhand smoke (SHS) odor complaints. < We measured particle size, particle composition, and VOCs. < Logistic regression models correctly identified SHS in 8 smoke odor periods. < Chemical mass balance analysis produced estimates of SHS in 6 of the 8 periods. < Identification and quantific...

We estimate ambient air PM2.5 time series from US EPA outdoor air monitoring data. We estimate the time series for population exposure to PM2.5 from secondhand smoke using CDC cotinine data. using a pharmacokinetic model Our analysis suggests that: • PM2.5 ambient air concentrations nationwide decreased from ~16 μg/m3 by 38% to 10 μg/m3 over 20 yea...

Personal exposure to air pollutants can be substantially higher in close proximity to an active source due to non-instantaneous mixing of emissions. The research presented in this paper quantifies this proximity effect for a non-buoyant source in 2 naturally ventilated homes in Northern California (CA), assessing its spatial and temporal variation...

The amount of light scattered by airborne particles inside an aerosol photometer will vary not only with the mass concentration, but also with particle properties such as size, shape, and composition. This study conducted controlled experiments to compare the measurements of a real-time photometer, the SidePak AM510 monitor (SidePak), with gravimet...

We sought all published or unpublished final reports of indoor and outdoor measurements of fine particulate matter (PM2.5) for commercial and tribal casinos in the US. This yielded data for 91 smoking casinos and 3 smoke-free casinos in 7 States: California (Jiang et al. 2010), Nevada (Achutan et al., 2009; York and Lee, 2010; Repace et al., in pre...

For modeling exposure close to an indoor air pollution source, an isotropic turbulent diffusion coefficient is used to represent the average spread of emissions. However, its magnitude indoors has been difficult to assess experimentally due to limitations in the number of monitors available. We used 30-37 real-time monitors to simultaneously measur...

Smoking bans often exempt casinos, exposing occupants to fine particles (PM(2.5)) from secondhand smoke. We quantified the relative contributions to PM(2.5) from both secondhand smoke and infiltrating outdoor sources in US casinos. We measured real-time PM(2.5), particulate polycyclic aromatic hydrocarbons (PPAH), and carbon dioxide (CO(2)) (as an...

This presentation describes a study of indoor air quality and exposures for a California casino

Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement pe...

Electrochemical sensors are commonly used to measure concentrations of gaseous air pollutants in real time, especially for personal exposure investigations. The monitors are small, portable, and have suitable response times for estimating time-averaged concentrations. However, for transient exposures to air pollutants lasting only seconds to minute...

Despite California's 1994 statewide smoking ban, exposure to secondhand smoke (SHS) continues in California's Indian casinos. Few data are available on exposure to airborne fine particles (PM2.5) in casinos, especially on a statewide basis. We sought to measure PM2.5 concentrations in Indian casinos widely distributed across California, exploring d...

Data are lacking on human exposure to air pollutants occurring in ground-level outdoor environments within a few meters of point sources. To better understand outdoor exposure to tobacco smoke from cigarettes or cigars, and exposure to other types of outdoor point sources, we performed more than 100 controlled outdoor monitoring experiments on a ba...

Cited By (since 1996): 7 , Export Date: 4 February 2013 , Source: Scopus , The following values have no corresponding Zotero field: Author Address: Department of Civil and Environmental Engineering, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699-5710, United States Author Address: Department of Civil and Environmental Engineering, Stan...

This poster presets measurements using the TSI 3007 condensation particle monitor of ultrafine particle concentrations (UFP, size 10-1,000 nm) measured in homes, restaurants, and automobiles. Time series graphs are included as well as a table of in-vehicle UFP concentrations measured on 17 drives on highways on the East and West Coast and a table o...

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 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...

Written by experts, Exposure Analysis is the first complete resource in the emerging scientific discipline of exposure analysis. A comprehensive source on the environmental pollutants that affect human health, the book discusses human exposure through pathways including air, food, water, dermal absorption, and, for children, non-food ingestion. The...

This study employed two continuous particle monitors operating on different measurement principles to measure concentrations simultaneously from common combustion sources in indoor, outdoor, and in-transit settings. The pair of instruments use (a) photo-charging (PC) operating on the principle ionization of fine particles that responds to surface p...

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 interconn...

Previous research on a continuously emitting source in a room has observed a “proximity effect,” or higher concentrations near the source. The pollutant is transported from the source throughout the room on thin, rapidly moving strands called “microplumes.” In 12 experiments in a home, we used a combustion source (a cigarette or an incense stick) n...

More than 300 air change rate experiments were completed in two occupied residences: a two-story detached house in Redwood City, CA, and a three-story townhouse in Reston, VA. A continuous monitor was used to measure the decay of SF6 tracer gas over periods of 1-18 hr. Each experiment first included a measurement of the air change rate with all ext...

Averaging time models based on empirical measurements have been developed for ambient data, but most averaging time models have lacked a theoretical basis, and few averaging time models have been developed for indoor air quality and exposure assessment applications. Previous human activity pattern-exposure models have required improved ways for han...

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-...

This paper presents a new statistical model designed to extend our understanding from prior personal exposure field measurements of urban populations to other cities where ambient monitoring data, but no personal exposure measurements, exist. The model partitions personal exposure into two distinct components: ambient concentration and nonambient c...

Personal monitoring studies have indicated that environmental tobacco smoke (ETS) and cooking are major indoor particulate sources in residential and nonindustrial environments. Continuous monitoring of fine particles improves exposure assessment by characterizing the effect of time-varying indoor sources. We evaluated a portable nephelometer as a...

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 exposure...

To provide new information on environmental tobacco smoke (ETS) levels from cigars, we conducted three types of experiments: (1) Measurements of carbon monoxide (CO) during 15 controlled experiments in an office where several cigar brands were machine -smoked; (2) Measurements of CO or respirable suspended particles (RSP) and particle -bound polycy...

Much progress has been made over four decades in developing, testing, and evaluating the performance of mathematical models for predicting pollutant concentrations from smoking in indoor settings. Although largely overlooked by the regulatory community, these models provide regulators and risk assessors with practical tools for quantitatively estim...

This paper develops a unified theoretical framework for understanding exposure to environmental pollutants and other agents. It reviews the scientific literature to describe the many diverse and often confusing ways in which the term "exposure" is being used. Using six criteria proposed for a useful framework, a set of quantitative definitions, whi...

INTRODUCTION Smoking in enclosed spaces exposes occupants to indoor air pollution from the by-products of tobacco combustion in confined spaces where airborne contaminant removal is slow and uneven. This chapter investigates the factors determining the indoor environmental tobacco smoke exposure from cigar smoking. Mathematical models allow the pre...

This article was published as a follow-up to the Feature Article, "A Quantitative Definition of Exposure and Related Concepts," published in the Journal of Exposure Analysis and Environmental Epidemiology, Volume 7, No. 4, pp. 411-138, 1997. This short article responds to various points raised by our fellow-scientist, Dr. David Mage about these qua...