Epidemiological Bases for Possible Air Quality Criteria for Carbon Monoxide

Exposures to adequate environmental levels of CO will increase COHb concentrations in human subjects. The amount of this increase is reasonably predictable, and must be considered in relation to exposure to CO in inhaled cigarette smoke as well as to occupational and domestic exposures. The increase in body COHb will result in some degree of impairment of tissue oxygenation.

Methods for estimating COHb levels in large populations are relatively simple. The assumption that an exposure to 30 ppm CO for eight hours will produce on the average, an increase in COHb of 5%, has been substantiated by available data.

Exposure for five hours to between 10 and 12 ppm of CO has been shown to increase the COHb levels in nonsmokers by at least 0.5%. Such an increase adds appreciably to the body burden of COHb in those who do not already have such a body burden from cigarette smoking. Longer exposures could have produced a somewhat greater increase.

Apart from increases in COHb, three possible effects have been a source of major consideration in epidemiologic studies. The first is the production of some persistent toxic reaction. This possibility has been examined with respect to occupational exposure, and the evidence for the occurrence of such a condition is insufficient.

The possible contribution of ambient community CO exposure to the mortality of persons hospitalized with myocardial infarction has been investigated. The evidence suggests that daily average CO values in excess of about 10 ppm may be associated with an increase in mortality in hospitalized patients with myocardial infarction. Substantiation of this impression will require a study of the prognosis of myocardial infarction patients in relationship to COHb levels measured at admission to the hospital.

Finally, in two studies, persons driving motor vehicles which were involved in accidents had higher COHb levels than "control" populations. Controls were not ideal, however. Possible mechanisms by which CO might affect the ability to drive a motor vehicle is suggested in the available data on CO effects upon visual sensitivity, psychological test performance and accurate estimation of time intervals. As little as 2 percent COHb can produce these effects in laboratory studies, and the available epidemiologic information confirms that such an increase in COHb levels among drivers might influence the frequency of accidents.

Specific areas where research is indicated to clarify uncertainties relating to health effects of CO are: 1. The increment in COHb which can be produced by exposures to an average of 20 ppm CO for an eight hour period and the increment which can be produced by 15 ppm for such a period and by 10 ppm for up to twenty-four hours.

2. The relationship of ambient CO levels and of COHb levels to the survival of hospitalized patients with myocardial infarction.

3. The prognostic significance with respect to cardiovascular conditions of elevated levels of COHb.

4. The relationship, if any, between ambient CO and COHb levels and the occurrence of motor vehicle accidents when weather and driving conditions, cigarette smoking, alcohol and drug use, and other factors are adjusted and controlled.

     

Real-time measurement of outdoor tobacco smoke particles

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.     

A Mercury Vapor Detector Based upon the Automatic Adjustment of Lamp Intensity to the Mercury Concentration

An office containing about 65 employees was found to have 8-h average CO concentrations of 18-26 ppm during a week in winter. On one Friday afternoon, 20 nonsmoking office workers had alveolar CO levels of 23 ± 3 ppm compared to levels of 8 ± 2 ppm in six nonsmoking workers in other offices in the same building. After a weekend at home, the affected office workers displayed reduced alveolar CO levels of 7 ± 2 ppm. The source of the high CO levels was attributed to a parking garage on the same level as the office. Closing fire doors and activating garage fans rectified the situation. The breath sampling method is found to require a correction factor based on the difference between the true alveolar CO and the CO level in the surrounding air. The methods and equipment employed in this study (personal air monitors, electronic data loggers, breath sampling) are recommended for screening and identifying potential CO problems in buildings with similar conditions.     

Real–Time Measurement of Outdoor Tobacco Smoke Particles

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 μg m^?3. OTS exhibited sharp spikes in particle mass concentration during smoking that sometimes exceeded 1000 μg 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 μg m^?3, with some average downwind levels exceeding 500 μg 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.     

Comparison of breath CO,CO exposure,and Coburn model predictions in the U.S. EPA Washington-Denver (CO) study

The U.S. EPA studied the carbon monoxide (CO) exposures and resulting breath CO concentrations of 625 non-smoking persons in Washington, D.C., and 454 non-smokers in Denver, CO, in the winter of 1982–83. Mean population-weighted breath concentrations were 5.1 ± 0.2 (SE) ppm in Washington and 7.2 ± 0.2 ppm in Denver. These values were correlated with the preceding personal air CO exposures (Spearman rank correlation coefficient r_s > 0.5, P < 0.0001) but not with the outdoor concentrations (r_s < 0.2). However, the breath measurements did not agree very closely with the personal exposures according to the current (Coburn) model relating alveolar CO to ambient CO. One reason for the discrepancy may have been the slight observed negative bias displayed by the personal monitors. A method of using the breath measurements to arrive at an improved estimate of personal exposures has been developed and applied. The method leads to an upward revision of exposure estimates: about 10% of the Washington target population of 1.22 million non-smokers are estimated to have exceeded the EPA 8-h ambient standard of 9 ppm during the winter of 1982–83, well above the 3.5% indicated by the personal monitor measurements.     

Particle Concentrations Inside a Tavern Before and After Prohibition of Smoking: Evaluating the Performance of an Indoor Air Quality Model

Abstract

Measurements were made of respirable suspended particles (RSP) in a large sports tavern on 26 dates over approximately two years in which smoking was allowed, followed by measurements on 50 dates during the year after smoking was prohibited. The smoking prohibition occurred without warning when the city government passed a regulation restricting smoking in local restaurants and taverns. Two follow-up field surveys, consisting of 24 and 26 visits, respectively, were conducted to measure changes in RSP levels after smoking was prohibited. No decrease in tavern attendance was evident after smoking was prohibited. During the smoking period, the average RSP concentration was 56.8 |ig/m3 above the outdoor concentrations, but the average abruptly dropped to 5.9 ug/m3 above outdoor levels—a 90% decrease— on 24 visits in the first two months immediately after smoking was prohibited (first follow-up study). A second set of 26 follow-up visits (matched by time of day, day of the week, and season to the earlier smoking visits) yielded an average concentration of 12.9 jig/m3 above the outdoor levels, or an overall decrease in the average RSP concentration of 77% compared with the smoking period. During the smoking period, RSP concentrations more than 100 ug/m3 above outdoor levels occurred on 30.7% of the visits. During the 50 nonsmoking visits, 92% of the RSP concentrations were less than 20 u,g/m3 above outdoor levels, and no concentration exceeded 100 ug/m3 on any nonsmoking visit. The data show there was a striking decline in indoor RSP concentrations in the tavern after smoking was prohibited. The indoor concentration observed in the nonsmoking periods (9.1 u.g/m3 average for all nonsmoking visits) was attributed to cooking and resuspended dust. A mathematical model based on the mass balance equation was developed that included smoking, cooking, and resuspended dust. Using cigarette emission rates from the literature, the tavern volume of 521 m3, and the air exchange rate measured in the tavern under conditions regarded by the management as "typical," the model predicted 42.5 ug/m3 for an average smoking count of 1.17 cigarettes, which compared favorably with the average concentration of 43.9 ng/m3 observed in the tavern. A regression analysis indicated that the active smoking count explained over 50% of the variation of the RSP concentrations measured on different dates. The mathematical model can be used to estimate RSP concentrations from smoking in other similar taverns under similar conditions.     

Improved Titrilog Sensitivity

ABSTRACT

A method was developed to reproducibly measure environmental tobacco smoke (ETS) components generated by different cigarettes. Measurements were carried out in an unventilated, controlled environment chamber. True ETS (the aged and diluted combination of exhaled mainstream plus sidestream smoke) was generated by human smokers. To reliably quantitate components normally present at trace levels, the comparisons were carried out at elevated ETS concentrations—greater than 40 times those typically encountered in “real-world” settings.

The method was applied to four commercially available cigarettes and a cigarette prototype that primarily heats tobacco. Forty-three properties and components of the gas and particulate phases of ETS generated by the different cigarettes were measured. Good precision of measurement was obtained both within and between tests. Statistically significant differences in the concentration of ETS components were observed among the different commercial cigarettes and between the commercial and prototype cigarettes. Most ETS components from the prototype cigarette were reduced by >90% when compared to the commercial cigarettes. The method was used to determine the effect of cigarette design changes on the generation of ETS.     

Consultant Guide/1978

Abstract

Biomarkers of methyl tertiary butyl ether (MTBE) exposure and the partitioning of inhaled MTBE into the body were investigated in a human chamber study. Two subjects were exposed to an environmentally relevant nominal 5,011 µg/m³ (1.39 ppm) MTBE for 1 hour, followed by clean–air exposure for 7 hours. Breath and blood were simultaneously sampled, while total urine was collected at prescribed times before, during, and after the exposure. Mass–balance and toxicokinetic analyses were conducted based upon the time series measurement of multiple body–burden endpoints, including MTBE in alveolar breath, and MTBE and tertiary butyl alcohol (TBA) in venous blood and urine.

The decay of MTBE in the blood was assessed by fitting the post–exposure data to a 2– or 3–exponential model that yielded residence times (τ) of 2–3 min, 15–50 min, and 3–13 h as measured by alveolar breath, and 5 min, 60 min, and 32 h as evaluated from venous blood measurements. Based on observations of lower than expected blood and breath MTBE during uptake and a decreasing blood–to–breath ratio during the post–exposure decay period, we hypothesize that the respiratory mucous membranes were serving as a reservoir for the retention of MTBE. The decay data suggest that 6–9% of the MTBE intake may be retained by this non–blood reservoir. The compartmental modeling was further used to estimate important parameters that define the uptake of inhaled MTBE. The first of these parameters is f, the fraction of C_air exhaled at equilibrium, estimated as 0.60 and 0.46 for the female and male subject, respectively. The second parameter is the blood–to–breath partition coefficient (P) estimated as ～18. The product of these parameters provides an estimate of the blood concentration at equilibrium as 8–11 times the air concentration. Blood TBA lagged MTBE levels and decayed more slowly (τ = 1.5–3 h), providing a more stable indication of longer term integrated exposure.

The concentration ranges of MTBE and TBA in urine were similar to that of the blood, ranging from 0.37 to 15 µg/L and 2 to 15 µg/L, respectively. In urine, MTBE and TBA by themselves bore little relationship to the exposure. However, the MTBE:TBA ratio followed the pattern of exposure, with peak values occurring at the end of the exposure (20– and 60–fold greater than pre–exposure values) before decaying back to pre–exposure levels by the end of the 7–h decay period. Urinary elimination accounted for a very small fraction of total MTBE elimination (<1%).     

Polycyclic aromatic hydrocarbons (PAHs) in human milk from Italian women: influence of cigarette smoking and residential area

The presence of PAH in breast milk collected from 32 smoking and non-smoking lactating women, residing in urban and rural areas of Tuscany (Italy) was investigated. The results indicated a significant contribution of tobacco smoke to the PAH contamination of milk: the condensate contained in the cigarettes smoked daily by each subject was strongly related with the polynuclear hydrocarbon content (R(2)=0.92, P<0.005). An experiment carried out under controlled exposure conditions to cigarette smoke allowed to demonstrate that individual metabolic activity and smoking habits affect the PAH concentration in milk samples. Mothers living in rural environments showed significantly lower PAH concentrations than those observed in urban subjects. The risk evaluation due to PAH ingestion via breast milk was assessed on the basis of the acceptable daily intake of Benzo(a)pyrene in drinking water, evidencing that a hazard cannot be excluded for heavy smokers residing in urban areas.     

Analytical solutions to compartmental indoor air quality models with application to environmental tobacco smoke concentrations measured in a house

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.     

Carcinogenic tryptophan pyrolysis products in cigarette smoke condensate and cigarette smoke-polluted indoor air

The carcinogenic tryptophan pyrolysis products, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido-[4,3-b]indole (Trp-P-2), have been measured in condensate of cigarette mainstream smoke by high-performance liquid chromatography. These carcinogens have been detected in indoor air as well as in the air of the outdoor environment. Levels of these carcinogens in indoor air were much higher than those in outdoor air. The source of these carcinogens in indoor air was determined to be cigarette smoke by the application of smoking machine studies. Concentrations of these carcinogens in indoor air increased markedly with an increase in cigarettes smoked. The results in this investigation suggest that cigarette smoking is a source of carcinogenic tryptophan pyrolysis products in the indoor environment. Our data also suggest that smokers are persistently exposed to the carcinogenic heterocyclic amines together with potent carcinogens such as polynuclear aromatic hydrocarbons and N-nitroso compounds.     

Environmental tobacco smoke particles in multizone indoor environments

Environmental tobacco smoke (ETS) is a major source of human exposure to airborne particles. To better understand the factors that affect exposure, and to investigate the potential effectiveness of technical control measures, a series of experiments was conducted in a two-room test facility. Particle concentrations, size distributions, and airflow rates were measured during and after combustion of a cigarette. Experiments were varied to obtain information about the effects on exposure of smoker segregation, ventilation modification, and air filtration. The experimental data were used to test the performance of an analytical model of the two-zone environment and a numerical multizone aerosol dynamics model. A respiratory tract particle deposition model was also applied to the results to estimate the mass of ETS particles that would be deposited in the lungs of a nonsmoker exposed in either the smoking or nonsmoking room. Comparisons between the experimental data and model predictions showed good agreement. For time-averaged particle mass concentration, the average bias between model and experiments was less than 10%. The average absolute error was typically 35%, probably because of variability in particle emission rates from cigarettes. For the conditions tested, the use of a portable air filtration unit yielded 65–90% reductions in predicted lung deposition relative to the baseline scenario. The use of exhaust ventilation in the smoking room reduced predicted lung deposition in the nonsmoking room by more than 80%, as did segregating the smoker from nonsmokers with a closed door.     

Impact of smoking on in-vehicle fine particle exposure during driving

Indoor smoking ban in public places can reduce secondhand smoke (SHS) exposure. However, smoking in cars and homes has continued. The purpose of this study was to assess particulate matter less than 2.5 μm (PM_2.5) concentration in moving cars with different window opening conditions. The PM_2.5 level was measured by an aerosol spectrometer inside and outside moving cars simultaneously, along with ultrafine particle (UFP) number concentration, speed, temperature and humidity inside cars. Two sport utility vehicles were used. Three different ventilation conditions were evaluated by up to 20 repeated experiments. In the pre-smoking phase, average in-vehicle PM_2.5 concentrations were 16–17 μg m^?3. Regardless of different window opening conditions, the PM_2.5 levels promptly increased when smoking occurred and decreased after cigarette was extinguished. Although only a single cigarette was smoked, the average PM_2.5 levels were 506–1307 μg m^?3 with different window opening conditions. When smoking was ceased, the average PM_2.5 levels for 15 min were several times higher than the US National Ambient Air Quality Standard of 35 μg m^?3. It took longer than 10 min to reach the level of the pre-smoking phase. Although UFP levels had a similar temporal profile of PM_2.5, the increased levels during the smoking phase were relatively small. This study demonstrated that the SHS exposure in cars with just a single cigarette being smoked could exceed the US EPA NAAQS under realistic window opening conditions. Therefore, the findings support the need for public education against smoking in cars and advocacy for a smoke-free car policy.     

Outdoor air pollution in close proximity to a continuous point source

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 backyard residential patio in which we released pure carbon monoxide (CO) as a tracer gas for continuous time periods lasting 0.5–2 h. The CO was emitted from a single outlet at a fixed per-experiment rate of 120–400 cc min^?1 (～140–450 mg min^?1). We measured CO concentrations every 15 s at up to 36 points around the source along orthogonal axes. The CO sensors were positioned at standing or sitting breathing heights of 2–5 ft (up to 1.5 ft above and below the source) and at horizontal distances of 0.25–2 m. We simultaneously measured real-time air speed, wind direction, relative humidity, and temperature at single points on the patio. The ground-level air speeds on the patio were similar to those we measured during a survey of 26 outdoor patio locations in 5 nearby towns. The CO data exhibited a well-defined proximity effect similar to the indoor proximity effect reported in the literature. Average concentrations were approximately inversely proportional to distance. Average CO levels were approximately proportional to source strength, supporting generalization of our results to different source strengths. For example, we predict a cigarette smoker would cause average fine particle levels of approximately 70–110 μg m^?3 at horizontal distances of 0.25–0.5 m. We also found that average CO concentrations rose significantly as average air speed decreased. We fit a multiplicative regression model to the empirical data that predicts outdoor concentrations as a function of source emission rate, source–receptor distance, air speed and wind direction. The model described the data reasonably well, accounting for ～50% of the log-CO variability in 5-min CO concentrations.     

Outdoor fine and ultrafine particle measurements at six bus stops with smoking on two California arterial highways—Results of a pilot study

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 heavily traveled California arterial highways with 3300–5100 vehicles per hour. At each bus stop, a smoker in the group smoked a cigarette. Gravimetrically calibrated continuous monitors were used to measure fine particle concentrations (aerodynamic diameter ≤2.5 µm; PM_2.5) in the breathing zones (within 0.2 m from the nose and mouth) of each participant. At each bus stop, ultrafine particles (UFP), wind speed, temperature, relative humidity, and traffic counts were also measured. For 13 cigarette experiments, the mean PM_2.5 personal exposure of the nonsmoker seated 0.5 m from the smoker during a 5-min cigarette ranged from 15 to 153 µg/m³. Of four persons seated on the bench, the smoker received the highest PM_2.5 breathing-zone exposure of 192 µg/m³. There was a strong proximity effect: nonsmokers at distances 0.5, 1.0, and 1.5 m from the smoker received mean PM_2.5 personal exposures of 59, 40, and 28 µg/m³, respectively, compared with a background level of 1.7 µg/m³. Like the PM_2.5 concentrations, UFP concentrations measured 0.5 m from the smoker increased abruptly when a cigarette started and decreased when the cigarette ended, averaging 44,500 particles/cm³ compared with the background level of 7200 particles/cm³. During nonsmoking periods, the UFP background concentrations showed occasional peaks due to traffic, whereas PM_2.5 background concentrations were extremely low. The results indicate that a single cigarette smoked outdoors at a bus stop can cause PM_2.5 and UFP concentrations near the smoker that are 16–35 and 6.2 times, respectively, higher than the background concentrations due to cars and trucks on an adjacent arterial highway.

Implications: Rules banning smoking indoors have been widely adopted in the United States and in many countries. Some communities are considering smoking bans that would apply to outdoor locations. Although many measurements are available of pollutant concentrations from secondhand smoke at indoor locations, few measurements are available of exposure to secondhand smoke outdoors. This study provides new data on exposure to fine and ultrafine particles from secondhand smoke near a smoker outdoors. The levels are compared with the exposure measured next to a highway. The findings are important for policies that might be developed for reducing exposure to secondhand smoke outdoors.     

Particulate matter emissions of different brands of mentholated cigarettes

Inhaling particulate matter (PM) in environmental tobacco smoke (ETS) endangers the health of nonsmokers. Menthol, an additive in cigarettes, attenuates respiratory irritation of tobacco smoke. It reduces perceptibility of smoke and therefore passive smokers may inhale ETS unnoticed. To investigate a possible effect of menthol on PM concentrations (PM₁₀, PM_2.5, and PM₁), ETS of four mentholated cigarette brands (Elixyr Menthol, Winston Menthol, Reyno Classic, and Pall Mall Menthol Blast) with varying menthol content was analyzed. ETS was generated in a standardized way using an automatic environmental tobacco smoke emitter (AETSE), followed by laser aerosol spectrometry. This analysis shows that the tested cigarette brands, despite having different menthol concentrations, do not show differences with regard to PM emissions, with the exception of Reyno Classic, which shows an increased emission, although the menthol level ranged in the midfield. More than 90% of the emitted particles had a size smaller than or equal to 1 µm. Regardless of the menthol level, the count median diameter (CMD) and the mass median diameter (MMD) were found to be 0.3 µm and 0.5 µm, respectively. These results point out that there is no effect of menthol on PM emission and that other additives might influence the increased PM emission of Reyno Classic.

Implications: Particulate matter (PM) in ETS endangers the health of nonsmokers and smokers. This study considers the effect of menthol, an additive in cigarettes, on PM emissions. Does menthol increase the amount of PM? Due to the exposure to secondhand smoke nearly 900,000 people die each year worldwide. The aim of the study is to measure the particle concentration (L^?1), mass concentration (µg m^?3), and dust mass fractions shown as PM₁₀, PM_2.5, and PM₁ of five different cigarette brands, including four with different menthol concentrations and one menthol-free reference cigarette, in a well-established standardized system.     

Vehicle Occupant Exposure to Carbon Monoxide

Abstract

This paper focuses on the auto commuting micro-environment and presents typical carbon monoxide (CO) concentrations to which auto commuters in central Riyadh, Saudi Arabia were exposed. Two test vehicles traveling over four main arterial roadways were monitored for inside and outside CO levels during eighty peak and off-peak hours extending over an eight month period. The relative importance of several variables which explained the variability in CO concentrations inside autos was also assessed. It was found that during peak hours auto commuters were exposed to mean CO levels that ranged from 30 to 40 ppm over trips that typically took between 25 to 40 minutes. The mean ratio of inside to outside CO levels was 0.84. Results of variance component analyses indicated that the most important variables affecting CO concentrations inside autos were, in addition to the smoking of vehicle occupants, traffic volume, vehicle speed, period of day and wind velocity. An increase in traffic volume from 1,000 to 5,000 vehicles per hour (vph) increased mean CO level exposure by 71 percent. An increase in vehicle speed from 14 to 55 km/h reduced mean CO exposure by 36 percent. The number of traffic interruptions had a moderate effect on mean concentrations of CO inside vehicles.     

Nicotine as a Marker for Environmental Tobacco Smoke: Implications of Sorption on Indoor Surface Materials

ABSTRACT

Recently developed models and data describing the interactions of gas-phase semi-volatile organic compounds with indoor surfaces are employed to examine the effects of sorption on nicotine's suitability as an environmental tobacco smoke (ETS) marker. Using parameters from our studies of nicotine sorption on carpet, painted wallboard, and stainless steel and previously published data on ETS particle deposition, the dynamic behavior of nicotine was modeled in two different indoor environments: a house and a stainless steel chamber. The results show that apparently contradictory observations of nicotine's behavior in indoor air can be understood by considering the effects of sorption under different experimental conditions. In indoor environments in which smoking has occurred regularly for an extended period, the sorbed mass of nicotine is very large relative to the mass emitted by a single cigarette. The importance of nicotine adsorption relative to ventilation as a gas-phase removal mechanism is reduced. Where smoking occurs less regularly or the indoor surfaces are cleaned prior to smoking (as in a laboratory chamber), nicotine deposition is more significant. Nicotine concentrations closely track the levels of other ETS constituents in environments with habitual smoking if the data are averaged over a period significantly longer than the period between cigarette combustion episodes. However, nicotine is not a suitable tracer for predicting ETS exposures at fine time scales or in settings where smoking occurs infrequently and irregularly.     

Interpreting the eight-hour national ambient air quality standard for carbon monoxide

There are two principal approaches to the 8-hour carbon monoxide standard: (1) 8-hour moving averages that culminate with every clock hour, and (2) nonoverlapping averages for consecutive 8-hour intervals. Examination of 1972 data for three example sites (Newark, NJ, Camden, NJ, and Spokane, WA) shows that the maximum and the “second high” control values derived from moving averages can be at least 20% higher than corresponding values detected by the consecutive 8-hour intervals. The natural fluctuation in the time of day when the maximum occurs and the variability in episode length make it doubtful that any framework of consecutive 8-hour intervals can adequately portray the essential characteristics of CO exposure. Prudence recommends choice of the moving 8-hour average as more sensitive to actual maximum levels and to short episodes, more faithful to the body’s integrating response to CO exposure, and more equitable in presenting comparisons among stations with differing patterns of daily variation.     

Reducing the Risk of Accidental Death Due to Vehicle-Related Carbon Monoxide Poisoning

ABSTRACT

Emissions of carbon monoxide (CO) from motor vehicles cause several hundred accidental fatal poisonings annually in the United States. The circumstances that could lead to fatal poisonings in residential settings with motor vehicles as the source of CO were explored. The risk of death in a garage (volume = 90 m³) and a single-family dwelling (400 m³) was evaluated using a Monte Carlo simulation with varying CO emission rates and ventilation rates. Information on emission rates was obtained from a survey of motor vehicle exhaust gas composition under warm idle conditions in California, and information on ventilation rates was obtained from a summary of published measurements in the U.S. housing stock. The risk of death ranged from 16 to 21% for a 3-hr exposure in a garage to 0% for a 1-hr exposure in a house. Older vehicles were associated with a disproportionately high risk of death. Removing all pre-1975 vehicles from the fleet would reduce the risk of death by one-fourth to two-thirds, depending on the exposure scenario. Significant efforts have been made to control CO emissions from motor vehicles with the goal of reducing CO concentrations in outdoor air. Substantial public health benefit could also be obtained if vehicle control measures were designed to take account of acute CO poisonings explicitly.