Carbon Monoxide: A Hazard to Fire Fighters

Carbon monoxide levels were measured in twenty-five fires in the city of Los Angeles to obtain information about fire fighters exposure to carbon monoxide. Levels as high as 3,000 ppm were observed for some fires. In general, when carbon monoxide levels were significantly elevated (> 100 ppm) the smoke was quite heavy and noxious, but in some cases the smoke was heavy and carbon monoxide levels were minimal. In two-story structures, the highest concentrations of carbon monoxide were found on the second-floor level and were usually (still elevated after the fire had been “knocked down” but was still smoldering. These data show that fire fighters are exposed to levels of carbon monoxide which could be a serious health hazard and may be related to the high incidence of heart disease in fire fighters.     

COHb% as a marker of cardiovascular risk in never smokers: results from a population-based cohort study

AIM: Carbon monoxide (CO) in blood as assessed by the COHb% is a marker of the cardiovascular (CV) risk in smokers. Non-smokers exposed to tobacco smoke similarly inhale and absorb CO. The objective in this population-based cohort study has been to describe inter-individual differences in COHb% in never smokers and to estimate the associated cardiovascular risk. METHODS: Of the 8,333 men, aged 34-49 years, from the city of Malm?, Sweden, 4,111 were smokers, 1,229 ex-smokers, and 2,893 were never smokers. Incidence of CV disease was monitored over 19 years of follow up. RESULTS: COHb% in never smokers ranged from 0.13% to 5.47%. Never smokers with COHb% in the top quartile (above 0.67%) had a significantly higher incidence of cardiac events and deaths; relative risk 3.7 (95% CI 2.0-7.0) and 2.2 (1.4-3.5), respectively, compared with those with COHb% in the lowest quartile (below 0.50%). This risk remained after adjustment for confounding factors. CONCLUSION: COHb% varied widely between never-smoking men in this urban population. Incidence of CV disease and death in non-smokers was related to COHb%. It is suggested that measurement of COHb% could be part of the risk assessment in non-smoking patients considered at risk of cardiac disease. In random samples from the general population COHb% could be used to assess the size of the population exposed to second-hand smoke.     

Effect of protective filters on fire fighter respiratory health during simulated bushfire smoke exposure

BACKGROUND: Bushfire fighters are potentially subject to risks from bushfire smoke. Although many different protective masks and filters are available, it is not clear which is the most effective from a health and safety perspective. The effect of protective filters on the respiratory health of Western Australian urban career fire fighters under controlled simulated conditions is investigated. METHODS: Sixty-four healthy Fire and Emergency Services Authority of Western Australia (FESA) urban career fire fighters were subjected to controlled simulated bushfire smoke in an open smoke chamber for 15 min. The fire fighters were allocated one of the three types of protective filters: particulate only (P), particulate/organic vapor (POV), and a particulate/organic vapor/formaldehyde (POVF) filter using a double-blind randomized procedure. Personal air sampling inside the fire fighters' masks, spirometry, oximetry, and self-reported symptom data were collected at baseline and at two time intervals after the smoke exposure. RESULTS: A significant decline in oxygen saturation was seen immediately after exposure, however, the decline was small and no significant relationships could be established between this and the type of filter used. A significantly higher number of participants in the P and POV filter groups self-reported an increase in coughing, wheezing, and shortness of breath compared to the POVF group. Air sampling demonstrated a significantly higher level of formaldehyde and acrolein inside the masks fitted with P filters compared to POV and POVF filters. CONCLUSIONS: Testing the effectiveness of P, POV, and POVF filters under controlled conditions has demonstrated that the POVF filter provides statistically significant better protection for the fire fighters' airways in a simulated bushfire exposure chamber.     

Mortality and cancer incidence in stockholm fire fighters

Fire fighters are exposed to irritating, asphyxiating, and toxic gases and aerosols, to psychological stress, and to physically demanding work. Due to differences in fire fighting techniques, exposure conditions for fire fighters differ among different countries. The purpose of this investigation was to study cancer incidence and mortality in fire fighters who have been working with fire fighting methods used in Sweden from the beginning of this century onwards. All male fire fighters employed for at least 1 year in the City of Stockholm during 1931–1983 were traced, and an index of the number of fires fought was calculated for each individual. The mortality during 1951–1986 (among 1, 116 fire fighters) was lower than expected (SMR = 82; 95% confidence interval 72–91) compared with local mortality rates, with a low mortality in circulatory diseases, obstructive lung diseases, violent deaths, and suicides. The cancer incidence in 1958–1986 was equal to the expected (SMR = 100; 95% confidence interval 83–119). However, an excess of stomach cancer (18 observed vs. 9.37 expected: SMR = 192, 95% CI 114–304) was observed. There was also a tendency for higher incidence and mortality in stomach and brain cancer with increasing number of fires. There were four deaths from brain cancer compared to 0.8 expected (SMR = 496; 95% CI 135–1270) in the highest exposure category. Fire fighters are, however, not systematically exposed to known stomach or brain carcinogens, and the results need confirmation in further studies with extensive exposure evaluations. © 1994 Wiley-Liss, Inc.     

Occupational exposures in California wildland fire fighting.

Industrial hygiene measurement of exposures to wildland fire fighters was conducted in northern California during three consecutive fire seasons (1986-1989) in conjunction with three separate health effects studies. Chemicals that were monitored included carbon monoxide, total and respirable particulates, polyaromatic hydrocarbons (PAHs), crystalline silica, aldehydes, and benzene. Measurements were taken at both wildland fires and prescribed (planned) burns. A variety of collection methods were employed--colorimetric detector tubes and a CO monitor were used for direct-reading area measurements; colorimetric diffusion tubes, filter cassettes, sorbent tubes, and passive vapor monitors were used for determining personal time-weighted average exposures. A new screening method (National Institute for Occupational Safety and Health Method 2539) was used to identify the presence of specific aldehydes. Results show that wildland fire fighters may at times be exposed to concentrations of carbon monoxide, total or respirable particulates, or silica at levels near or higher than recommended occupational exposure limits, although group means were generally well below the limits. Time-weighted average formaldehyde levels, measured in a few instances above 0.37 mg/m3 (0.3 ppm), indicate a potential for formaldehyde-induced eye or respiratory irritation under these conditions. Certain characteristics of the work such as high altitude, temperature, and breathing rate; extended work shifts; and additional off-shift exposures suggest that adjustment of 8-hr exposure limits may be necessary to provide adequate protection. In part, because of the rigors of performing industrial hygiene measurements under fire fighting conditions, data are limited and could not be considered representative of the full range of exposures fire fighters may encounter.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transient decrease of exhaled nitric oxide after acute exposure to passive smoke in healthy subjects

Nitric oxide (NO) is produced and detected in the exhalate from the respiratory tract where it plays important regulatory functions. Exhaled nitric oxide (eNO) concentrations are reduced in active cigarette smokers between cigarettes and in nonsmoking subjects during short-term exposure to environmental tobacco smoke. In this study, the authors evaluated eNO before and after an acute exposure to environmental tobacco smoke in healthy, nonsmoking subjects (n = 12). Baseline eNO levels were measured by chemiluminescence at baseline (1 hr before exposure), shortly after the end of exposure, and 10 and 30 min after the end of exposure. Mean room air NO concentration increased from 3 ppb to 4 ppm (range, 560 ppb-8.5 ppm) during the exposure period. Carboxyhemoglobin levels were assessed before and after the exposure with spectrophotometry. All subjects had decreased eNO with exposure to environmental tobacco smoke (mean +/- standard error of the mean: 16.65 +/- 1.35 ppb to 13.86 +/- 1.33 ppb; p < .001). These concentrations remained significantly decreased at 10 min and recovered within 30 min. No modifications in airway resistance or increase in carboxyhemoglobin levels were observed. Exposure to environmental tobacco smoke transiently--but consistently--decreased eNO concentration in healthy, nonsmoking subjects, suggesting that second-hand smoke can directly affect NO in the airway environment.     

Carbon monoxide levels in the breath of smokers and nonsmokers: effect of domestic heating systems.

Breath and ambient (room) carbon monoxide (CO) levels were measured in a random sample of 168 adults in their own homes. The levels of breath CO in the 69 smokers ranged from 3 ppm to over 100 ppm, 74% being above 10 ppm; mean levels in the 99 nonsmokers were lower than in the smokers, 79% being below 6 ppm. In the remaining 21% of nonsmokers with higher breath levels than expected, the ambient CO was also found to be elevated, ranging up to 38 ppm. A close correlation in the nonsmokers was found between the breath and ambient CO levels (r = 0.952, p less than 0.001). The rooms with the elevated ambient CO levels (above 5 ppm) were those which, at the time of testing, were being heated by gas radiant heaters, open fires or stoves. The maximum ambient CO in the rooms of smokers with non CO generating heating was 16 ppm. The results suggest that many people, both smokers and nonsmokers, may be at risk from CO generated by certain domestic heating systems and that nonsmokers are far more likely to be exposed to high levels of CO from these sources than from being in a room with a heavy smoker. Poor ventilation associated with the current trend towards excluding all draughts is likely to exacerbate the situation for both smokers and nonsmokers.     

Heart rates in fire fighters using light and heavy breathing equipment: similar near-maximal exertion in response to multiple work load conditions

Intense exertion is an occupational hazard inherent to fire fighting. This study was designed to look at the exertion levels that fire fighters attain during a fire fighting exercise when using (1) no self-contained breathing apparatus (SCBA), (2) light SCBA, and (3) heavy SCBA. Exertion levels were measured as a function of the heart rate increase relative to the maximum predicted heart rate determined by a standard treadmill exercise test. Five fire fighters wore electrocardiographic monitors during a routine fire fighting exercise. Heart rates increased rapidly to 70% to 80% of maximum within the first minute and then plateaued at 90% to 100% until the attack on the fire was completed. There was no significant difference between exertion levels when using no SCBA, light SCBA, and heavy SCBA (split-plot analysis of variance, p greater than .25). These results suggest that fire fighters attain an intense level of physical activity quickly and maintain that level as long as they are actively engaged in fighting fire. These results also suggest that regardless of the weight of the SCBA, if employed, fire fighters exert themselves from 85% to 100% of their maximum and adjust their work output to maintain that near-maximal level.     

Transient Decrease of Exhaled Nitric Oxide after Acute Exposure to Passive Smoke in Healthy Subjects

Nitric oxide (NO) is produced and detected in the exhalate from the respiratory tract where it plays important regulatory functions. Exhaled nitric oxide (eNO) concentrations are reduced in active cigarette smokers between cigarettes and in nonsmoking subjects during short-term exposure to environmental tobacco smoke. In this study, the authors evaluated eNO before and after an acute exposure to environmental tobacco smoke in healthy, nonsmoking subjects (n = 12). Baseline eNO levels were measured by chemiluminescence at baseline (1 hr before exposure), shortly after the end of exposure, and 10 and 30 min after the end of exposure. Mean room air NO concentration increased from 3 ppb to 4 ppm (range, 560 ppb-8.5 ppm) during the exposure period. Carboxyhemoglobin levels were assessed before and after the exposure with spectrophotometry. All subjects had decreased eNO with exposure to environmental tobacco smoke (mean ± standard error of the mean: 16.65 ± 1.35 ppb to 13.86 ± 1.33 ppb; p < .001). These concentrations remained significantly decreased at 10 min and recovered within 30 min. No modifications in airway resistance or increase in carboxyhemoglobin levels were observed. Exposure to environmental tobacco smoke transiently–but consistently–decreased eNO concentration in healthy, nonsmoking subjects, suggesting that second-hand smoke can directly affect NO in the airway environment.     

A longitudinal study of pulmonary function in fire fighters

Pulmonary function changes among fire fighters were evaluated by re-examining 632 Baltimore city fire fighters six to ten years after a baseline examination. Spirometry was used to determine forced expiratory volume in 1 second (FEV1). Information about exposures was obtained by questionnaire and by combining data from fire department records regarding the number of fires fought by fire fighting units with individual work histories. Men who never wore a mask while extinguishing fires experienced a 1.7 times greater rate of FEV1 decline than mask wearers. Men with ammonia exposure experienced a rate of decline 1.7 times greater than non-exposed men. Neither length of time spent in exposed jobs nor number of responses were associated with the rate of decline. Active fire fighters experienced a rate of decline 2.5 times greater than those who had retired or resigned. Some effects differed between men who were able to perform repeatable pulmonary function tests and those who were not.     

Exhaled carbon monoxide levels correlate with incidence of oral mucosal lesions independent of smoking status

Carbon monoxide (CO) is an important component of tobacco smoke, but also environmental toxicity. This study analyzed possible correlation between exhaled CO level and oral health indicators in two geographically distributed populations during health-promoting public events organized for local communities in cities with high and low environmental pollution in Poland (907 patients). Self-reported, instructor-led, oral health questionnaire was developed to monitor current and previous mucosal lesion incidence. Exhaled CO correlated with subjects smoking status and environmental CO exposure: highest in smoking inhabitants of Krakow (12 ppm), with lower levels in smokers from Kozienice (6.5 ppm) and non-smokers from Krakow (6 ppm), and lowest for Kozienice non-smokers (2 ppm) (p < 0.001). After propensity score matching and adjustment for smoking status, demography and comorbidities odds ratio for mucosal lesion incidence was 1.46 (1.31–1.63), p < 0.001) per 1 ppm increase of exhaled CO level. This result might implicate a possible role of environmental pollution factors in oral health pathology.     

Reproductive hazards of fire fighting. II. Chemical hazards

Studies of the health of fire fighters have historically focused on non-malignant respiratory disease and cancer. More recently, concerns have surfaced about reproductive health effects in many areas of the workforce, including fire fighting. These concerns prompted this review of chemical exposures that may contribute to adverse reproductive health outcomes in male as well as female fire fighters. A review of the industrial hygiene literature was undertaken to identify agents commonly found in fire smoke. These agents were then examined for evidence of reproductive toxicity or mutagenicity/carcinogenicity. This profile of chemical agents and their reproductive toxicities permits a qualitative determination that fire fighters are exposed to potential reproductive toxicants as a part of their normal fire fighting duties. Considerations for mitigating these risks are also discussed.     

Annoyance and irritation by passive smoking

The acute irritating and annoying effects of smoke have been investigated in field and laboratory studies by examining the concentration of some smoke components in air. In the workplace, 30 to 70% of the indoor carbon monoxide, nitrogen oxide, and particulate concentrations are due to tobacco smoke; 25-40% of the employees are disturbed and/or annoyed by smoke and 25% suffer from eye irritation at work. Subjective eye, nose, and throat irritations and eye blink rate increase with increasing smoke concentration and increasing exposure duration. Irritation is due mainly to the particulate phase of environmental tobacco smoke, whereas the gas phase is, to a large extent, responsible for annoyance. It is concluded that healthy individuals can tolerate an environmental tobacco smoke level that corresponds to a carbon monoxide concentration of 1.5 to 2.0 ppm. Above these limits, countermeasures to protect passive smokers are necessary. In order not to exceed the upper tolerable threshold limit of 2.0 ppm carbon monoxide, it is necessary to have a fresh air supply of 33 m3 per hour per cigarette smoked. Special attention should be paid to groups of people with increased sensitivity to environmental tobacco smoke, e.g., asthmatics, allergic individuals, chronic bronchitis sufferers, and children.     

Impact of the improved patsari biomass stove on urinary polycyclic aromatic hydrocarbon biomarkers and carbon monoxide exposures in rural Mexican women

Background: Cooking with biomass fuels on open fires results in exposure to health-damaging pollutants such as carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs), and particulate matter.Objective: We compared CO exposures and urinary PAH biomarkers pre- and postintervention with an improved biomass stove, the Patsari stove.Methods: In a subsample of 63 women participating in a randomized controlled trial in central Mexico, we measured personal CO exposure for 8 hr during the day using continuous monitors and passive samplers. In addition, first-morning urine samples obtained the next day were analyzed for monohydroxylated PAH metabolites by gas chromatography/isotope dilution/high-resolution mass spectrometry. Exposure data were collected during the use of an open fire (preintervention) and after installation of the improved stove (postintervention) for 47 women, enabling paired comparisons.Results: Median pre- and postintervention values were 4 and 1 ppm for continuous personal CO and 3 and 1 ppm for passive sampler CO, respectively. Postintervention measurements indicated an average reduction of 42% for hydroxylated metabolites of naphthalene, fluorene, phenanthrene, and pyrene on a whole-weight concentration basis (micrograms per liter of urine), and a 34% reduction on a creatinine-adjusted basis (micrograms per gram of creatinine). Pre- and postintervention geometric mean values for 1-hydroxypyrene were 3.2 and 2.0 μg/g creatinine, respectively.Conclusion: Use of the Patsari stove significantly reduced CO and PAH exposures in women. However, levels of many PAH biomarkers remained higher than those reported among smokers.     

Respiratory Irritants in Australian Bushfire Smoke: Air Toxics Sampling in a Smoke Chamber and During Prescribed Burns

Bushfire smoke contains an array of organic and inorganic compounds, including respirable and inspirable particles, aldehydes, and carbon monoxide. These compounds have been found to be a health hazard for firefighters in the United States. Despite the high frequency of bushfires in Australia, analyses of bushfire smoke components are scarce. As part of an occupational health study investigating the respiratory health effects of bushfire smoke in firefighters, air toxics sampling was undertaken in a smoke chamber and during prescribed burns. Levels of formaldehyde and acrolein were demonstrated at respectively 60% and 80% of the Short Term Exposure Limit in the smoke chamber. Carbon monoxide levels exceeded the peak limit of 400 ppm significantly. Although concentrations were lower during the prescribed burns, the study shows that Australian bushfire smoke contains air toxics of concern and provides justification for further research into the levels of air toxics measured at bushfires and the associated health impacts.     

Repeated validation of parental self-reported smoking during pregnancy and infancy: a prospective cohort study of infants at high risk for allergy development

Exposure to environmental tobacco smoke (ETS) during fetal life and infancy is closely related to the smoking habits of the parents. Estimates of exposure to ETS require valid and detailed information on changes in cigarette smoking over time. The objective was to test the validity of self-reported smoking among parents during pregnancy and early childhood in a cohort of children at high risk for allergy development by measurement of exhaled carbon monoxide (CO). The cohort comprised 117 families enrolled from the general population of pregnant women at admission to antenatal care. Data on parental tobacco smoking were obtained by interview and exhaled CO was measured (Micro-Smokerlyzer(R)) in parents twice during pregnancy and when the child was 6 and 18 months old. The median (range) exhaled CO levels were 3 (0-10) parts per million (ppm) for non-smokers and 15 (1-39) ppm for smokers (P < 0.0005). A receiver operating characteristic (ROC) analysis was performed at each examination. The areas under the ROC curve were high for both mothers (between 0.88 and 0.99) and fathers (between 0.87 and 0.89), indicating exhaled CO as a good diagnostic tool for determining smoking status. Comparing the ROC areas obtained for mothers from late pregnancy and during infancy with the area from early pregnancy showed no statistical differences (P = 0.21, 0.43 and 0.44 respectively) and the same was true for fathers during infancy (P = 0.81). The level of 8 ppm was used as the cut-off between smokers and non-smokers, based on data from a pilot study. Using CO as a diagnostic tool for smoker status showed very high specificity (between 97 and 100%), indicating that very few persons claiming to be non-smokers had CO levels higher than 8 ppm. In conclusion, the validity of interview-obtained self-reported smoking among parents during pregnancy and early childhood was high. Repeated interviews and CO measurements in a prospective study design did not change the validity, indicating a low risk of information bias. A structured interview combined with measurement of exhaled CO is a valid and reliable method for estimating ETS exposure to the fetus and young infant.     

Sidestream tobacco smoke exposure acutely alters human nasal mucociliary clearance.

Nasal mucociliary clearance (NMC) is a biomarker of nasal mucosal function. Tobacco smokers have been shown to have abnormal NMC, but the acute effect of environmental tobacco smoke (ETS) on nonsmokers is unknown. This study evaluated acute tobacco smoke-induced alterations in NMC in 12 healthy adults. Subjects were studied on 2 days, separated by at least 1 week. Subjects underwent a 60-min controlled exposure at rest to air or sidestream tobacco smoke (SS) (15 ppm CO) in a controlled environmental chamber. One hour after the exposure, 99mTc-sulfur colloid was aerosolized throughout the nasal passage and counts were measured with a scintillation detector. Six out of 12 subjects showed more rapid clearance after smoke exposure than after air exposure, and 3/12 had rapid clearance on both days. However, substantial decreases in clearance occurred in 3/12 subjects, all of whom had a history of ETS rhinitis. In two subjects, more than 90% of the tracer remained 1 hr after tracer administration (2 hr after smoke exposure). Understanding the basis for biologic variability in the acute effect of tobacco smoke on NMC may advance our understanding of pathogenesis of chronic effects of ETS.     

Smoke exposure among women in Haiti: The case for improved stoves

Indoor smoke exposure is responsible for two million deaths per year and has been studied globally, but the impacts of exposure have not yet been evaluated in Haiti, the Western hemisphere's poorest nation. This study measures the disproportionate impact of indoor smoke exposure on the women and children of Haiti. We studied 2296 clinic patients in four Haitian villages to determine the extent of carbon monoxide (CO) exposure, using carboxyhemoglobin saturation in the blood as a proxy for overall smoke exposure. We predicted CO levels to be higher in women, who traditionally perform the majority of cooking duties, and in children who accompany their mothers. CO levels averaged 4.9% in women and 3.4% in men. Women of child-bearing age carried a minimum relative risk (RR) for CO exposure of 1.22, relative to all males and younger females. Older females carried no significant difference in risk. Children averaged the lowest CO exposure among all cohorts. These findings demonstrate the burden of indoor smoke exposure that falls disproportionately on women in these regions of Haiti. Global efforts to mitigate indoor exposure have demonstrated the health, economic, environmental and social improvements that are possible by tackling this problem.     

Environmental carbon monoxide from cigarette smoking—a critique

It is often asserted that tobacco smoke in the atmosphere of public places constitutes a health hazard to exposed nonsmokers because of the environmental carbon monoxide generated during the burning of a cigarette. Cigarette smoking is an insignificant source of carbon monoxide in the overall atmosphere as compared with other natural and man-made sources. Even in tightly closed spaces with a large percentage of smokers, only rarely is it possible to build up concentrations which would exceed the established threshold limiting values for extended exposures. Examples include meeting rooms, houses, buses, and aircraft. Carboxyhemoglobin levels in nonsmokers resulting from carbon monoxide in environmental tobacco smoke are below the amount needed to produce the maximum allowable limit of 4% carboxyhemoglobin in the blood, as suggested by the World Health Organization. No strong evidence has been found indicating adverse effects in healthy individuals from concentrations of carboxyhemoglobin at or below these levels.     

Passive and active maternal smoking as measured by serum cotinine: the effect on birthweight.

To determine how maternal exposure to environmental tobacco smoke affects birthweight, maternal sera obtained from 3529 pregnant women around 27 weeks gestation were analyzed for cotinine, a metabolite of nicotine. Based on cotinine levels, nonsmokers were divided into those exposed to environmental tobacco smoke (2-10 ng/mL) and those unexposed (< 2 ng/mL), and smokers were divided into tertiles. Compared with unexposed nonsmokers' infants, infants of exposed nonsmokers averaged 45 g less (P = .28) after adjustment for confounders, and smokers' infants averaged 78, 191, and 233 g less for the first, second, and third cotinine tertiles, respectively. Birthweight decreased 1 g for every nanogram per milliliter of cotinine increase (P < .001).