Response of ciliated epithelium to ozone and sulfuric acid

The effects of ozone (O₃), sulfuric acid (H₂SO₄), and their interaction on ciliary activity were investigated. Following in vivo exposure to various concentrations of O₃ and H₂SO₄, ciliary activity of isolated tracheal ring cultures was microscopically determined under stroboscopic illumination. Assay of tracheal rings immediately after a 2-hr exposure to 880 μg H₂SO₄/m³ showed a significant decrease (P < 0.0001) in ciliary beating frequency from controls. Following 72 hr in vitro maintenance, there was still a significant depression (P < 0.01) in ciliary activity of treatment cultures. In vivo recovery studies indicated that ciliary activity had returned to the normal range 72 hr after exposure. Exposure to 196 μg O₃/m³ for 3 hr resulted in no significant difference from controls in ciliary activity. Experiments designed to investigate the effects of a sequential exposure to O₃ followed by H₂SO₄ indicated a significant decrease (P < 0.05) in the ciliary beating frequency of exposed animals which was less than that observed with H₂SO₄ alone. As indicated by the results of these studies, combined action experiments are extremely relevant in assessing the toxicity of environmental pollutants.     

Short-term effect of ozone on the pulmonary function of children in primary school.

The objective of this study was to evaluate the short-term effect of ambient air pollution on the pulmonary function of schoolchildren. We sampled 941 children in primary school in three communities in Taiwan (Sanchun, Taihsi, and Linyuan). The nearby stations of the Taiwan air quality monitoring network provided the hourly ambient concentrations of sulfur dioxide, carbon monoxide, ozone, particulate matter < or = to 10 microm in aerodynamic diameter, and nitrogen dioxide. Spirometry was performed once for each sampled child. We also obtained the status of indoor air pollution and chronic respiratory disease history by using a structured questionnaire. Multivariate linear model analysis was used to evaluate pulmonary function effects of each pollutant in addition to determinants of indoor air pollution and meteorologic conditions. We found a significantly negative association of peak O(3) concentration on the day before spirometry with individual forced vital capacity and forced expiratory volume in 1 sec. The decrease in children's lung function can occur at peak hourly O(3) concentrations < 80 ppb. The slope of lung function decrease for Taiwanese children is approximately 1 mL/ppb for peak hourly O(3) exposure.     

Similarity between man and laboratory animals in regional pulmonary deposition of ozone

Predicted pulmonary ozone (O₃) does curves obtained by model analysis of the transport and removal of O₃ in the lungs of guinea pigs, rabbits, and man indicate that a general similarity exists among these species in the shapes of the dose curves. An overview of the major features of the lower airway mathematical model used is presented. This model predicts that the respiratory bronchioles receive the maximum O₃ dose. For exposures corresponding to tracheal O₃ concentrations greater than 100 μg/m³ (0.05 ppm), the predicted respiratory bronchiolar dose for rabbits was found to be twice that for guinea pigs and 80% of that for man. Sensitivity analyses are presented for model parameters relating to the treatment of the chemical reactions of O₃ in man is examined. The consistency and similarity of the dose curves for the three species lend strong support to the validity of extrapolating to man the results obtained on animals exposed to O₃.     

The effect of duration of exposure on sulfuric acid-induced pulmonary function changes in asthmatic adolescent subjects: a dose-response study.

To evaluate the pulmonary effects of varying doses of sulfuric acid, adolescent subjects with asthma were exposed to 35 or 70 micrograms/m3 sulfuric acid for 45 or 90 min. Exposure was carried out during intermittent moderate exercise. The pulmonary functions measured before and after exposure were FEV1, FVC, and total respiratory resistance. The 45 min exposures were associated with larger decreases in FEV1 (-6% or -3%) than the 90 min exposures (-1% or +2%). Analysis of variance of the change in FEV1 among the exposures revealed that the 45 min exposure to 35 micrograms/m3 was significant (p = 0.03). The p value for 45 min exposure to 70 micrograms/m3 was not significant (p = 0.08). Using analysis of variance, neither of the 90 min exposures was associated with a significant decrease in FEV1 compared to air exposure. Also, none of the changes in FVC or RT was significant. When baseline to post-exposure changes were compared for each of the five test atmospheres using paired t tests, both of the 45 min exposures were associated with statistical significance (p < 0.001 for 35 micrograms/m3 and p < 0.005 for 70 micrograms/m3). This baseline to post exposure change was not statistically significant for the 90 min exposures. The reason for the lesser effect on pulmonary function at increased exposure duration is not known; it may be due to changes in either varying deposition patterns or changes in buffering capacity of the cells lining the airways. With respect to individual sensitivities to H2SO4, the data showed a significant consistency across test atmospheres.     

Acute effects of ozone on pulmonary function of cyclists receiving antioxidant supplements

OBJECTIVES: To identify whether acute lung function effects of ozone can be modulated by antioxidant vitamin supplementation. METHODS: Amateur cyclists (n = 26) were studied in the summer of 1994 in The Netherlands. Repeated lung function measurements were performed with a rolling seal spirometer after training sessions or competitive races on four to 14 occasions. The cyclists were assigned to two study groups. The supplementation group (n = 12) received antioxidant supplements (15 mg beta-carotene, 75 mg vitamin E, and 650 mg vitamin C) once a day for three months. The control group did not receive supplementation. For each subject, lung function after exercise was regressed on the previous eight hour mean ozone concentration. The individual regression coefficients were pooled for each study group and weighted with the inverse of the variance. RESULTS: The eight hour mean ozone concentration was 101 micrograms/m3 (30 to 205 micrograms/m3). For the supplementation group, there was no effect of ozone on FVC, FEV1, peak expiratory flow (PEF), and maximal mid-expiratory flow (MMEF). For the control group the mean coefficients were negative, except for MMEF. The difference between the groups was 2.08 (95% confidence interval (95% CI) 1.31 to 2.85) ml/microgram/m3 for FVC, 1.66 (95% CI 0.62 to 2.70) for FEV1, 6.83 (95% CI 3.17 to 10.49) for PEF, and 0.42 (95% CI -1.38 to 2.22) for MMEF. CONCLUSION: The results suggest that antioxidant vitamin supplementation protects against acute effects of ozone on lung function in heavily exercising amateur cyclists.

 

     

The effect of controlled ozone exposure on human lymphocyte function

The effects of ozone (O₃) on cell-mediated immunity were studied in 16 human subjects exposed to 1176 μg/m³ O₃ (0.6 ppm) for 2 hr in an environmentally controlled exposure chamber. Venous blood samples were taken before and immediately after controlled air and O₃ exposures, as well as at 72 hr, 2 and 4 weeks, and at one random time at least 1 month after treatment. The relative frequency of T lymphocytes in blood and the in vitro blastogenic response of lymphocytes to phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), and Candida albicans were determined. During the course of the experiment, no statistically significant changes were observed in the number of T lymphocytes that form spontaneous rosettes with sheep erythrocytes. The response of T lymphocytes to PHA was significantly reduced (P < 0.05) in samples taken at 2 and 4 weeks following O₃ exposure. Normal response to PHA was observed at 2 months post-O₃ exposure. No statistically significant changes in lymphocyte responses to Con A. PWM, or Candida were seen. These results show that one 2 hr exposure of humans to 0.6 ppm O₃ may lead to a transient suppression of the PHA-stimulated blastogenic transformation of peripheral blood lymphocytes. The data indicate that the blastogenic response to PHA of human lymphocytes is exquisitely sensitive to O₃ exposure and could serve as a bioassay for evaluating subtle changes in cellular immunity induced by O₃ and possibly other pollutants.     

The effect of starvation on skeletal muscle function in man

Measuring skeletal muscle function may be a diagnostic aid to detect malnutrition. To evaluate this hypothesis 11 lean women were studied before and after 5 days of total starvation. Skeletal muscle function was assessed as hand grip strength and as adductor pollicis muscle function after electrical stimulation of the ulnar nerve. The muscle function variables were force of contraction at 5, 10, 20 and 50 Hz stimulation, relaxation rate and endurance. In addition some currently used anthropometric and biochemical nutritional indices were serially determined. Hand grip strength was decreased (p < 0.05) and the function of the adductor pollicis muscle was altered with a higher contraction force at 10 Hz (p < 0.01), a slower relaxation rate (p < 0.05) and a reduced endurance (p < 0.05). These changes were all within the normal ranges. Triceps skin fold and arm muscle circumference were not changed after a mean weight loss of 3.3 kg (p < 0.05). However blood glucose, insulin and triiodothyronine all decreased (p < 0.01) indicating a metabolic adaptation to starvation. Prealbumin (p < 0.05) and fibronectin (p < 0.01) were also lowered. In conclusion, skeletal muscle function was significantly altered after five days of total starvation. However, to identify short term nutritional depletion in clinical practice the changes in muscle function were too small to be diagnostically useful.     

Effects of ozone and other pollutants on the pulmonary function of adult hikers.

This study evaluated the acute effects of ambient ozone (O3), fine particulate matter (PM2.5), and strong aerosol acidity on the pulmonary function of exercising adults. During the summers of 1991 and 1992, volunteers (18-64 years of age) were solicited from hikers on Mt. Washington, New Hampshire. Volunteer nonsmokers with complete covariates (n = 530) had pulmonary function measured before and after their hikes. We calculated each hiker's posthike percentage change in forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), the ratio of these two (FEV1/FVC), forced expiratory flow between 25 and 75% of FVC(FEF25-75%), and peak expiratory flow rate (PEFR). Average O3 exposures ranged from 21 to 74 ppb. After adjustment for age,sex, smoking status (former versus never), history of asthma or wheeze, hours hiked, ambient temperature, and other covariates, there was a 2.6% decline in FEV1 [95% confidence interval (CI), 0.4-4.7; p = 0.02] and a 2.2% decline in FVC (CI, 0.8-3.5; p =0.003) for each 50 ppb increment in mean O3. There were consistent associations of decrements in both FVC (0.4% decline; CI,0.2-0.6, p = 0.001) and PEFR (0.8% decline; CI, 0.01-1.6; p = 0.05) with PM2.5 and of decrements in PEFR (0.4% decline; CI, 0.1-0.7; p = 0.02) with strong aerosol acidity across the interquartile range of these exposures. Hikers with asthma or a history of wheeze (n = 40) had fourfold greater responsiveness to ozone than others. With prolonged outdoor exercise, low-level exposures to O3, PM2.5, and strong aerosol acidity were associated with significant effects on pulmonary function among adults. Hikers with a history of asthma or wheeze had significantly greater air pollution-related changes in pulmonary function.     

Exposure-effect relationship of selected pulmonary function measurements in subjects exposed to ozone

Summary Healthy adult male volunteer subjects were exposed to 0.15, 0.3, 0.45 and 0.5 ppm ozone (O₃) with and without intermittent light exercise. The results suggest that the subject's level of exercise during exposure is considerably related to the magnitude of changes in lung function and the occurrence rate of respiratory symptoms at any given O₃ concentration, and that among healthy subjects there is a considerable range of reactivity to O₃ exposure. A level of 0.15 ppm O₃ with intermittent light exercise produced a significant decrease of specific airway conductance in most subjects and coughing during deep inspiration in five of 15 subjects, while a level of 0.5 ppm O₃ produced fewer effects when the subject did not exercise. The nonsmoker is more reactive to O₃ than the smoker. The subject's level of exercise during exposure and his smoking habit are two important factors in evaluating the exposure-effect relationship of O₃.     

Double-blind intervention trial on modulation of ozone effects on pulmonary function by antioxidant supplements

The aim of this study was to investigate whether the acute effects of ozone on lung function could be modulated by antioxidant vitamin supplementation in a placebo-controlled study. Lung function was measured in Dutch bicyclists (n = 38) before and after each training session on a number of occasions (n = 380) during the summer of 1996. The vitamin group (n = 20) received 100 mg of vitamin E and 500 mg of vitamin C daily for 15 weeks. The average ozone concentration during exercise was 77 microg/m3 (range, 14-186 microg/m3). After exclusion of subjects with insufficient compliance from the analysis, a difference in ozone exposure of 100 microg/m3 decreased forced expiratory volume in 1 second (FEV1) 95 ml (95% confidence interval (CI) -265 to -53) in the placebo group and 1 ml (95% CI -94 to 132) in the vitamin group; for forced vital capacity, the change was -125 ml (95% CI -384 to -36) in the placebo group and -42 ml (95% CI -130 to 35) in the vitamin group. The differences in ozone effect on lung function between the groups were statistically significant. The results suggest that supplementation with the antioxidant vitamins C and E confers partial protection against the acute effects of ozone on FEV1 and forced vital capacity in cyclists.     

Duration of increased pulmonary function sensitivity to an initial ozone exposure

The metabolic and pulmonary function effects were investigated in six non-smoking young adults who were exposed for 2 hours (22 degrees C WBGT) to: filtered air (FA) 0.45 ppm ozone (DAY1); and two days later to a second exposure to 0.45 ppm ozone (DAY2). The subjects alternated 20-minute periods of rest and 20-minute periods of bicycle ergometer exercise at a workload predetermined to elicit a ventilatory minute volume (VE) of 27 L/min (BTPS). Functional residual capacity (FRC) was determined pre- and post-exposure. Forced vital capacity (FVC) was determined before and after exposure, as well as 5 minutes after each exercise period. Heart rate was monitored throughout the exposure, and VE, oxygen uptake (VO2), respiratory rate (fR), and tidal volume (VT) were measured during the last 2 minutes of each exercise period. There were no changes in any variable consequent to FA exposure. Both ozone exposures induced significant (P less than 0.05) decrements in FVC; FEV1.0 (forced expiratory volume in 1 second); FEV3.0 (forced expiratory volume in 3 seconds); FEF25-75% (average flow rate between 25% and 75% of FVC); and total lung capacity (TLC). The decrements following the DAY2 ozone exposure were significantly greater than following DAY1, and averaged 7.2 percentage points greater than those following the DAY1 exposure.     

Effects of ozone on pulmonary function: the relationship of response to dose.

A dose-response relationship for the effects of ozone on pulmonary function in humans has been derived using the concept of internal thoracic dose. This quantity, which represents the dose of inhaled pollutant capable of reaching and affecting target sites in the lower respiratory tract, was estimated using a mathematical model derived in part from theory and in part from data obtained using human and animal subjects. The model was applied to ozone exposures of individuals ranging in age from infants to adults over age 65 and for exercise conditions ranging from rest to heavy exercise (greater than 6 times resting minute ventilation). The dose model was successfully used to compare results from clinical studies in which subjects were exposed under disparate conditions of exercise, exposure concentration and exposure duration. The model can also be applied to estimate doses to populations exposed to ambient pollution. The effects of ozone on pulmonary function in adults and children were evaluated using the model. On the basis of dose of ozone (micrograms O3 per kg body mass), children, aged 8 to 15 years, and adults were equally sensitive. When dose is analyzed as a function of age, the data suggest that children, under the age of 6 years, receive greater doses to respiratory tract tissues than do older children or adults, under equivalent conditions of exposure.     

Combined exposure to carbon disulfide and sulfuric acid simultaneously increases the risk of hand dermatitis in rayon industry

OBJECTIVE: To evaluate the association between hand dermatitis (HD) and occupational exposure to CS(2) and to determine whether combined exposure to CS(2) and H(2)SO(4) exhibits a higher risk of HD. METHODS: In all, 110 subjects from a rayon factory were recruited and their exposure was classified into CS(2) exclusively, H(2)SO(4) exclusively, combined exposure, and nonexposure control based on workers' job characteristics. A dermatologist was designated in the diagnosis of HD on palm and dorsal sites for each subject. Other confounding factors including detergent, glove wearing, and participation in wet work were determined using a person-to-person questionnaire interview from 37 randomly selected subjects. RESULTS: Significant elevated odds ratios (ORs) for HD were found in CS(2) exclusively (44.8, P < 0.01) and combined exposure (49.0, P < 0.001) compared with control. Dose-response trends of ORs for HD were found across control, single exposure, and combined exposure for both CS(2) and H(2)SO(4). CONCLUSIONS: HD could occur resulting from occupational exposure to CS(2) alone. This study was unable to affirm that the exposure to H(2)SO(4) alone is associated with HD due to limited H(2)SO(4) exposure subjects. The combined exposure to both CS(2) and H(2)SO(4) simultaneously could increase the risk of HD. The control remedy in preventing dermal contact with either CS(2) or H(2)SO(4) among the rayon workers should be performed immediately.     

Lack of ozone effect on plasma concentrations of retinol,ascorbic acid,and tocopherol

Plasma concentrations of vitamin A, C, and E were measured in mature female rabbits exposed to 0.1 to 0.6 ppm of ozone for 3 h. No significant changes were found in the plasma concentration of any of the measured vitamins.