Asphyxiant Gases Research Articles

Ivanovo-Voznesensk War Industry Committee in 1915–1917: Problems and Achievements

The article examines the activities of the Ivanovo-Voznesensk military-industrial committee in 1915– 1917. Close attention to the object of study is determined by the fact that Ivanovo-Voznesensk was the center of the largest textile region in Russia, and the local military-industrial committee united enterprises with a total number of more than 30 thousand workers. On the basis of the analysis of the archival documents of the committee, the author comes to the conclusion that the sole direction of its activity was the supply of the army with military equipment: the production of grenade and shell cases, and the production of asphyxiant gas. For this, special enterprises (shell and phosgene plants) were founded, generously financed by the members of the Committee. They regularly carried out deliveries for the military department. On the other hand, the local textile enterprises, which fulfilled large defense orders for the supply of fabrics, found themselves outside the sphere of influence of the military-industrial committee. All factories received orders and reported on them independently. Based on this, the thesis is confirmed that the military-industrial committees were not monopolists in the distribution of military orders. Even the attempts of local manufacturers, with the help of the military-industrial committee, to ensure the allocation of additional labor, raw materials, fuel and equipment were not very successful. As a result, no more than 40 % of the capacities of the Ivanovo-Voznesensk textile industry were mobilized for “defense production”. In addition, there is absolutely no trace of the role of the local military-industrial committee in the political organization of the bourgeoisie in Ivanovo-Voznesensk. This can be attributed to the fact that, on the one hand, the committee solved mainly economic problems, and, on the other hand — that the local bourgeoisie had other economic and political organizations that had operated long before the committee was created.

A two-decade review of butane toxicity as a substance of abuse.

Butane, an aliphatic hydrocarbon with explosive and flammable properties, is widely misused especially by young people. Acting as an asphyxiant gas, butane mainly targets the central nervous and cardiovascular systems. We aimed to review butane-attributed toxicities due to its harmful use or misuse reported in a two-decade period. We searched English-language publications reporting butane toxicities from 2000 up to 2021 and collected data on age, gender, route and source of exposure, country of origin, clinical presentation and outcome. Among 54 butane's harmful use/misuse cases identified in the literature, there were 11 survivors successfully discharged from the hospital. Patients were predominantly males with a mean age ± SD of 23 ± 13 years. The main route of exposure was inhalation. Manifestations were mainly cardiac and neurological. Majority of the cases were reported from Europe and Japan. To conclude, butane exposure is at risk of severe central nervous system and cardiac toxicities, which may result in a fatal outcome. Therefore, in the event of a sudden or suspicious death in a young individual, our findings suggest that butane's harmful use/misuse should be considered as a potential differential diagnosis.

Experimental study on the thermal runaway and fire behavior of LiNi0.8Co0.1Mn0.1O2 battery in open and confined spaces

With the increasing deployment of large-scale lithium ion batteries (LIBs), thermal runaway (TR) and fire behavior are significant potential risks, especially for high energy density cells. A series of thermal abuse tests and hazard analysis on 117 Ah LiNi0.8Co0.1Mn0.1O2/graphite LIBs were performed under two conditions, “open space” and “confined space”. In open space tests, the fire behavior of LIBs was characterized with respect to the TR process, temperature characteristics, mass variation, voltage, heat release rate and gas release. To simulate the application scenarios in electric vehicles, a confined cabinet was introduced. The effects of state of charge and confined cabinet on the fire behavior of individual cell were analyzed. Furthermore, a real-scale scenario was considered for the evaluation of fire-induced toxicity using Fractional Effective Dose (FED) and Fractional Effective Concentration (FEC) models. The obtained results show that the effects of asphyxiant gases are more significant than those of irritant gases. The maximum FEC and FED values are greater than the critical threshold of 1, indicating the catastrophic toxicity in such fire scenarios. The minimum fresh air renewal rate required is computed to provide quantitative guides for ventilation management, firefighting and rescue.

Two cases of hypoxic encephalopathy caused by simple asphyxial gas poisoning

This article analyzes the clinical manifestations and magnetic resonance imaging (MRI) data of 2 patients with hypoxic encephalopathy after simple asphyxia gas poisoning. Both patients were in a moderate coma after being poisoned, and the arterial blood lactic acid level and carbon dioxide partial pressure were higher than the normal range within 1 week after poisoning. Two patients were cured and discharged after being treated with oxygen therapy and glucocorticoids. The prognosis was good.

Application of nasal high flow oxygen therapy in acute mass asphyxia poisoning with pulmonary bullae

Objective: To explore the observation and nursing of patients with acute mass asphyxia poisoning with pulmonary bullae treated by nasal high-flow humidification and oxygen therapy. Methods: Review and summarize the data of 5 patients with acute mass asphyxial gas poisoning with pulmonary vesicles who were admitted to the department of toxicology of this hospital in June 2019 and received nasal high-flow humidification and oxygen therapy. The oxygenation index, airway humidification and prognosis were observed. Results: All the 5 patients were successfully transferred to nasal catheter for oxygen inhalation after nasal high-flow humidification and orygen therapy without intubation. When discharged from the hospital without oxygen, pH: 7.36-7.42, PO(2):82-106 mmHg, PCO(2):32-39 mmHg. All the white blood cells and myocardial enzymes were normal, and there was no brain injury, perinasal skin damage and abdominal distension. Conclusion: Nasal high-flow humidification and oxygen therapy can effectively improve the efficacy of oxygen therapy for patients with acute mass asphyxial gas poisoning with pulmonary vacuoles.

Smoke toxicity of rainscreen façades

The toxic smoke production of four rainscreen façade systems were compared during large-scale fire performance testing on a reduced height BS 8414 test wall. Systems comprising ‘non-combustible’ aluminium composite material (ACM) with polyisocyanurate (PIR), phenolic foam (PF) and stone wool (SW) insulation, and polyethylene-filled ACM with PIR insulation were tested. Smoke toxicity was measured by sampling gases at two points - the exhaust duct of the main test room and an additional ‘kitchen vent’, which connects the rainscreen cavity to an occupied area. Although the toxicity of the smoke was similar for the three insulation products with non-combustible ACM, the toxicity of the smoke flowing from the burning cavity through the kitchen vent was greater by factors of 40 and 17 for PIR and PF insulation respectively, when compared to SW. Occupants sheltering in a room connected to the vent are predicted to collapse, and then inhale a lethal concentration of asphyxiant gases. This is the first report quantifying fire conditions within the cavity and assessing smoke toxicity within a rainscreen façade cavity.

A comprehensive investigation on the thermal and toxic hazards of large format lithium-ion batteries with LiFePO4 cathode

Toxic gases released from lithium-ion battery (LIB) fires pose a very large threat to human health, yet they are poorly studied, and the knowledge of LIB fire toxicity is limited. In this paper, the thermal and toxic hazards resulting from the thermally-induced failure of a 68 Ah pouch LIB are systematically investigated by means of the Fourier transform infrared spectroscopy (FTIR) and 1/2 ISO full scale test room. The LIBs with higher state of charge (SOC) are found to have greater fire risks in terms of their burning behavior, normalized heat release rate, and fire radiation, as well as the concentration of toxic gases. Specifically, the thermal hazards are evaluated by combining the effects of convective and radiative heat. The major toxic gases detected from the online analysis are CO, HF, SO2, NO2, NO and HCl. Furthermore, Fractional Effective Dose (FED) and Fractional Effective Concentration (FEC) models are used to quantitatively assess the overall gas toxicity. Results show that the effects of irritant gases are much more significant than those of asphyxiant gases. HF and SO2 have much greater toxicity than the other fire gases. The maximum FEC value is approaching the critical threshold in such fire scenarios.

Toxic Gases

This review looks at the potential causes, diagnoses, and possible treatments for three asphyxiant gases: carbon monoxide, hydrogen cyanide, and hydrogen sulfide, Exposure to these gases can lead to central nervous system depression, unconsciousness, and death due to tissue hypoxia. These gases are among the most common causes of fatalities related to toxic gas poisoning, with carbon monoxide responsible for 36% and hydrogen sulfide 7.7%. It is necessary to remove victims affected by poisoning immediately from the source of the toxic gas, administer oxygen, and assess their stability. As symptoms of these gases can differ widely, ranging from broad and unspecific to highly morbid, and may require different levels of care, the correct diagnosis should also rely on inferences from the patient history and the context of the admission, including evidence of fire and chemical reactions. Normobaric oxygen and hyperbaric oxygen are the two main treatments for carbon monoxide, although studies have been inconclusive in regards to the effectiveness of hyperbaric oxygen. The Cyanokit (containing hydroxocobalamin) is considered to be more effective for hydrogen cyanide when compared with the Cyanide Antidote Kit due to the former’s low toxicity and high effectiveness. Hydrogen sulfide is often used as a suicide agent, the mortality of which is close to 100%. Figures show the mechanisms by which the asphyxiant gases carry out their negative effects on the human body. Tables show the half-life of carboxyhemoglobin with oxygen therapy and a comparison between the Cyanide Antidote Kit and the Cyanokit. This review contains 3 figures, 13 tables, and 44 references. Keywords: Inhalation, poisoning, carbon monoxide, cyanide, methemoglobin, carboxyhemoglobin, hydrogen sulfide, smoke

Toxic Gases

This review looks at the potential causes, diagnoses, and possible treatments for three asphyxiant gases: carbon monoxide, hydrogen cyanide, and hydrogen sulfide, Exposure to these gases can lead to central nervous system depression, unconsciousness, and death due to tissue hypoxia. These gases are among the most common causes of fatalities related to toxic gas poisoning, with carbon monoxide responsible for 36% and hydrogen sulfide 7.7%. It is necessary to remove victims affected by poisoning immediately from the source of the toxic gas, administer oxygen, and assess their stability. As symptoms of these gases can differ widely, ranging from broad and unspecific to highly morbid, and may require different levels of care, the correct diagnosis should also rely on inferences from the patient history and the context of the admission, including evidence of fire and chemical reactions. Normobaric oxygen and hyperbaric oxygen are the two main treatments for carbon monoxide, although studies have been inconclusive in regards to the effectiveness of hyperbaric oxygen. The Cyanokit (containing hydroxocobalamin) is considered to be more effective for hydrogen cyanide when compared with the Cyanide Antidote Kit due to the former’s low toxicity and high effectiveness. Hydrogen sulfide is often used as a suicide agent, the mortality of which is close to 100%. Figures show the mechanisms by which the asphyxiant gases carry out their negative effects on the human body. Tables show the half-life of carboxyhemoglobin with oxygen therapy and a comparison between the Cyanide Antidote Kit and the Cyanokit. This review contains 3 figures, 13 tables, and 44 references. Keywords: Inhalation, poisoning, carbon monoxide, cyanide, methemoglobin, carboxyhemoglobin, hydrogen sulfide, smoke

Toxic Gases

This review looks at the potential causes, diagnoses, and possible treatments for three asphyxiant gases: carbon monoxide, hydrogen cyanide, and hydrogen sulfide, Exposure to these gases can lead to central nervous system depression, unconsciousness, and death due to tissue hypoxia. These gases are among the most common causes of fatalities related to toxic gas poisoning, with carbon monoxide responsible for 36% and hydrogen sulfide 7.7%. It is necessary to remove victims affected by poisoning immediately from the source of the toxic gas, administer oxygen, and assess their stability. As symptoms of these gases can differ widely, ranging from broad and unspecific to highly morbid, and may require different levels of care, the correct diagnosis should also rely on inferences from the patient history and the context of the admission, including evidence of fire and chemical reactions. Normobaric oxygen and hyperbaric oxygen are the two main treatments for carbon monoxide, although studies have been inconclusive in regards to the effectiveness of hyperbaric oxygen. The Cyanokit (containing hydroxocobalamin) is considered to be more effective for hydrogen cyanide when compared with the Cyanide Antidote Kit due to the former’s low toxicity and high effectiveness. Hydrogen sulfide is often used as a suicide agent, the mortality of which is close to 100%. Figures show the mechanisms by which the asphyxiant gases carry out their negative effects on the human body. Tables show the half-life of carboxyhemoglobin with oxygen therapy and a comparison between the Cyanide Antidote Kit and the Cyanokit. This review contains 3 figures, 13 tables, and 44 references. Keywords: Inhalation, poisoning, carbon monoxide, cyanide, methemoglobin, carboxyhemoglobin, hydrogen sulfide, smoke

Facing Emerging Risks in Carbon Sequestration Networks. A Comprehensive Source Modelling Approach

Tackling risks in emerging infrastructures is a key point in making them acceptable and safer. Carbon Sequestration pipeline networks, as part of the Carbon Capture and Storage chains, are linked to the handling of large amounts of CO2 and may be subjected to failures and ruptures. This results in large pressurized and multiphase releases of CO2 that behaves as a denser-than-air and asphyxiant gas. The lack of a comprehensive modelling approach in this sense makes employed risk safety procedures often unreliable and lacking.In this work, a comprehensive modelling approach, based on self-collected experimental data, is proposed with the aim of filling existing gaps. Results well match experimental data and the modelling procedure allows for the estimation of characteristic parameters linked to heat transfer phenomena and the incidence of geometry and operative conditions on the release evolution.The occurrence of the solid phase and the applicability of the isothermal hypothesis is discussed showing that specific geometric and operative conditions are required.

Epidemiological and occupational characteristics of occupational chemical poisoning in Tianjin city during 2006-2015

Objective: To provide scientific evidence for the prevention and control measures of acute and chronic occupational poisoning by analyzing the epidemiological and occupational characteristics of occupational chemical poisoning cases reported in Tianjin city during 2006-2015. Methods: In September 2016, based on the China Disease Control and Prevention Information System, a database of occupational poisoning cases in Tianjin from 2006 to 2015 was established. The epidemiological characteristics of occupational poisoning were analyzed including three distributions firstly, and then the occupational characteristics were analyzed such as length of service, industry distribution and source of poison. Results: There were 174 occupational poisoning patients in Tianjin from 2006 to 2015, including 16 cases of acute poisoning (9.20%) and 158 cases of chronic poisoning (90.8%) , and the proportion of occupational poisoning cases reported in Binhai New Area is the highest. The number of reported cases of chronic occupational poisoning shows a downward trend. Occupational poisoning cases are concentrated mainly in the age of 40-60 years and length of service of 10-20 years. The high incidence of occupational poisoning mainly exists in the chemical raw materials and chemical manufacturing industry and general, professional equipment manufacturing industry. Acute poisoning was mainly by asphyxial gas (50.00%) , and chronic poisoning was mainly by organic solvent (43.67%) . Conclusion: The distribution of occupational poisoning cases in diverse toxic types and regions in Tianjin are quite different. The occupational safety precautions of the chemical raw materials and chemical products manufacturing and occupational poisoning control work in Binhai new area should be strengthened to reduce the occurrence of occupational poisoning.

Risk assessment in combustion toxicology: Should carbon dioxide be recognized as a modifier of toxicity or separate toxicological entity?

To characterize the accumulated hazards associated with the inhalation of gases typical of combustion products, a time-integrated value known as the fractional effective dose (FED) is used. This FED is maintained by the International Organization for Standardization (ISO) and made publicly available as the Standard ISO 13571. The current FED calculation related to asphyxiant gases is based on non-human primate data to estimate the 50% probability of humans to be incapacitated or not being able to execute any escape paradigm from fires. The objective of this paper was to compare two to calculate FEDs of the most common mixture of asphyxiant fire gases CO, HCN, and CO2. The first was based on the current ISO 13571 (draft) standard, the alternative second method applied the conceptual principles established for the derivation of Acute Emergency Response Planning Guideline values. The alternative approach applied one third of the non-lethal threshold concentration (LC01) as the most suitable and robust Point of Departure (POD) to estimate the threshold characterizing ‘impairment of escape’ in the absence of post-exposure mortality. The hyperventilation correction factor for CO2 of ISO 13571 was replaced by a separate term that accounts for the inherent acute toxicity of CO2. This analysis supports the conclusion that the current ISO 13571 standard misjudges the impact of the acute toxicity elicited by concentrations of CO2 exceeding ≈6%. While underestimating the hazards attributable to CO2, the hyperventilation adjustment factor suggested by this standard is biased to markedly overestimate the hazards assigned to CO and HCN in fire effluents.

Acute inhalation toxicity of carbon monoxide and hydrogen cyanide revisited: Comparison of models to disentangle the concentration × time conundrum of lethality and incapacitation

Contemporary emergency response planning guidelines are stratified to consider the threshold for serious toxicity and/or impairment of escape, relative to the potentially lethal level above this threshold and the lower level at which individuals should not experience or develop effects more serious than mild irritation. While harmonized testing guidelines and risk assessment paradigms are available for the quantification of thresholds for lethality or establishing no adverse effect levels, the quantification of ‘impairment of escape’ appears to be a more elusive goal. Approaches were explored in context with CO and HCN in past experimental combustion toxicology studies to estimate the time available for escape. This point of departure (POD) was compared with the non-lethal threshold (LC01) and one third thereof from published recent acute inhalation studies in rats examining the Cxt-matrix of both CO and HCN. The findings from this analysis suggest that the rat delivers the most consistent data. However, it remains challenging yet to bridge the behavioral variables of human behavior typical of escape to any surrogate animal model. For the asphyxiant gases examined, the PODs characterizing ‘impairment of escape’ were difficult to distinguish from those indicative of impending death. No specific modeled carboxyhemoglobin (COHb) level could be linked to onset of incapacitation. In summary, the higher ventilation of rats (kg body weight adjusted) renders this species even more susceptible than heavy breathing humans. LCt01 × 1/3 values derived from the comprehensive Cxt matrix of rat inhalation studies are considered to be most suitable and robust to estimate the human equivalent threshold (POD) of ‘impairment of escape’.

Toxic Gases

This review looks at the potential causes, diagnoses, and possible treatments for three asphyxiant gases: carbon monoxide, hydrogen cyanide, and hydrogen sulfide, Exposure to these gases can lead to central nervous system depression, unconsciousness, and death due to tissue hypoxia. These gases are among the most common causes of fatalities related to toxic gas poisoning, with carbon monoxide responsible for 36% and hydrogen sulfide 7.7%. It is necessary to remove victims affected by poisoning immediately from the source of the toxic gas, administer oxygen, and assess their stability. As symptoms of these gases can differ widely, ranging from broad and unspecific to highly morbid, and may require different levels of care, the correct diagnosis should also rely on inferences from the patient history and the context of the admission, including evidence of fire and chemical reactions. Normobaric oxygen and hyperbaric oxygen are the two main treatments for carbon monoxide, although studies have been inconclusive in regards to the effectiveness of hyperbaric oxygen. The Cyanokit (containing hydroxocobalamin) is considered to be more effective for hydrogen cyanide when compared with the Cyanide Antidote Kit due to the former’s low toxicity and high effectiveness. Hydrogen sulfide is often used as a suicide agent, the mortality of which is close to 100%. Figures show the mechanisms by which the asphyxiant gases carry out their negative effects on the human body. Tables show the half-life of carboxyhemoglobin with oxygen therapy and a comparison between the Cyanide Antidote Kit and the Cyanokit. This review contains 3 highly rendered figures, 2 tables, 43 references, and 5 MCQs.

Hydrogen Sulfide Intoxication with Dilated Cardiomyopathy

Hydrogen sulfide (H 2 S) is a colorless, heavier-than-air, inflammable, highly toxic irritant and chemical asphyxiant gas, which has a characteristic rotten-egg odor that is detectable at concentrations as low as 0.5 ppb, but this warning property may be lost in 2 to 15 min at concentrations over 100 ppm through olfactory fatigue . Hydrogen sulfide is generated naturally by decaying sulfur-containing proteins and is released from sewage sludge, liquid manure, sulfur hot springs, and natural gas. It is also a by-product of many industrial processes, including petroleum refining, sewage disposal, mining, wood pulp processing, rayon manufacturing, manure processing, sugar-beet processing, fish processing and hot-asphalt paving . Hydrogen sulfide is especially risky in confined spaces such as fishing-ship holders, manure pits, and sewers. In the United States, 52 deaths related to hydrogen sulfide were reported from 1993 to 1999 in various industries. The toxic mechanism of hydrogen sulfide comprises inactivating cytochrome oxidase in mitochondria and then preventing the cellular metabolism of oxygen. Via this mechanism, hydrogen sulfide can induce hypoxic brain damage and hypoxic cardiac damage as well as mucosal irritation and pulmonary edema. Nevertheless, few cases of cardiac damage following hydrogen sulfide exposure have been reported. We here report a case of dilated cardiomyopathy after hydrogen sulfide inhalation in a sewer worker, the first case report of dilated cardiomyopathy caused by hydrogen sulfide. Case Presentation

Clinical and Diagnostic Features of Delayed Hypoxic Leukoencephalopathy

Clinical and Diagnostic Features of Delayed Hypoxic Leukoencephalopathy

An Assessment of Gases in Oxygen-Deficient Hay Silos and the Effects of Forced Ventilation

Many modern tower silos used in the agricultural industry for hay and grain storage are oxygen-limiting by design. Forced-air ventilation using a forage blower is a method commonly used to decrease concentrations of toxic and asphyxiant gases and to increase the O2 content within a silo headspace prior to worker entry. This article describes the methods used to measure gas concentrations and the results obtained from a pilot study by the Washington Fatality Assessment and Control Evaluation (FACE) program of two oxygen-limiting forage tower silos in eastern Washington State. The silos were monitored for oxygen (O2), nitrogen dioxide (NO2), and carbon dioxide (CO2). Measured O2 concentrations were low in all areas of the headspaces monitored for both silos. After beginning forced-air ventilation, O2 concentrations within the silo headspace returned to ambient levels within 8 to 20 min. Nitrogen dioxide levels exceeded the Washington Industrial Safety and Health Act (WISHA) short-term exposure limit (STEL) in the silo that was filled six days earlier (silo 2), but not in the silo that was filled four days earlier (silo 1). The NO2 concentration in silo 2 decreased to below the WISHA STEL within 15 min of starting ventilation but began to rise shortly after ventilation was stopped. Carbon dioxide, which was only measured in silo 1, was detected at 2% within the headspace of this silo. The carbon dioxide concentration decreased to <1% within 3 min of starting ventilation.

Toxicity Assessment Of Products Of Combustion Of Flexible Polyurethane Foam

The scientific literature on the toxicity of products of combustion of flexible polyurethane foam is reviewed to assess its potential for use in toxic hazard analysis. Combustion modes examined include pyrolysis/thermal decomposition, smoldering, and open flaming, and under ventilated flaming combustion. The body of work indicates that victims exposed to products of combustion from flaming polyurethane will result in %COHb’s generally consistent with simple CO exposure, despite the clear toxicological role of HCN. The N-gas fractional effective dose methodology for asphyxiant gases is an appropriate methodology for prediction of incapacitation due to exposure to products of combustion from flaming polyurethane. Conversely, there is significant scientific evidence that smoldering polyurethane foam produces as yet unidentified toxic species that results in deaths during the exposure and that the N-gas fractional effective dose methodology is not appropriate for smoldering combustion. Pyrolysis/thermal decomposition results in post-exposure deaths, consistent with irritant gases. The N-gas model is also not appropriate for pyrolysis/thermal decomposition. There are significant limitations in the experimental methods available that have had a negative impact on the study of toxic hazards. Adsorption and transport of toxicants on smoke particles, loss of toxicants to walls, and more chemically complex toxicants tend to be little studied or considered. There is a need to encourage more sophisticated chemical and physical analysis of fire effluents for complex toxic organic species. It can be argued that there is still a place for animal models when analytical methods and our mechanistic understanding of toxicology of complex organic species are lacking.

Ventilatory responses to rebreathing in infants exposed to maternal smoking

This study assessed the effect of maternal smoking during pregnancy on ventilatory and waking responses of infants to a respiratory challenge. This challenge mimicked the time-course and concentration of gases that an infant would experience rebreathing face-down into soft bedding. Control (C; n= 97) and smokers' infants (SM; n= 96) were studied at ages 1 and 3 mo. Asphyxial gas (hypercapnia/hypoxia) was delivered to the supine sleeping baby via a hood by slowly altering the inspired air: CO2 maximum 5% and O2 minimum 13.5%. Respiratory pattern was recorded by inductive plethysmography as the sum of ribcage and abdominal movements. The change in ventilation with inspired CO2 was measured over 5–6 min of the test. The slope of a linear curve fit relating inspired CO2 to the logarithm of ventilation was taken as a quantitative measure of ventilatory asphyxial sensitivity (VAS). Protective responses were graded from 1: no waking and an estimated arterial carbon dioxide tension (PaCO2) ±60mmHg (least protective), to 4: fully awake (most protective). The results showed VAS was higher in SM infants than controls: +0.03 (p= 0.04). The oxygen saturation (SaO2) of SM infants fell -0.4% (p= 0.02) more than SaO2 of controls despite a greater tidal volume increase: +13.0% (p= 0.04). Overall protective responses were the same between groups, but grade 1, although rare, was found in 7 SM infants and only 4 control infants; this difference was not significant. Conclusion: The study did not confirm the postulate that infants of mothers who smoked during pregnancy have a reduced ventilatory response or raised waking thresholds.