Effects of long-term exposure to low levels of ozone: a review.

Available literature regarding long-term effects of ozone on animals and humans is reviewed. Emphasis is placed on reports that have appeared since 1976, but some earlier reports are cited for completeness and perspective. This review shows that ozone concentration is more important than duration of exposure in determining the effects of an ozone exposure (dose). This conclusion calls into question the validity of the Time-Weighted Average (TWA) as an index of severity of ozone exposure. The literature review further reveals a wide variation in susceptibility of different animal species to ozone, making it difficult to apply results of animal experiments to humans. It further appears that a dose of ozone that is acutely innocuous is also innocuous over the long term. The effects of a symptom-producing dose of ozone are initially cumulative for the first two or three exposures; then an adaptive response may ensue that involves a plateau of response or even reversal. These effects are shown by both animals and humans. The mechanisms are unknown. Ozone probably causes damage by the free radical formation. Free radical scavengers, such as vitamin E and C, may provide protection against ozone damage.

Pulmonary and symptom threshold effects of ozone in airline passenger and cockpit crew surrogates.

Previous studies showed that the ozone concentration for pulmonary and symptom threshold effects in flight attendant surrogates lies between 0.20 and 0.30 ppmv for a 3-h exposure with intermittent treadmill exercise at 1829 m (MSL) stimulated cabin altitude. In the present study of sedentary occupants of the in-flight airline cabin, the same protocol was used except for omitting all treadmill exercise. Symptoms were assessed with a standardized questionnaire. Pulmonary function was assessed using standardized quantitative spirometry. Male smoker and nonsmoker airline passanger and cockpit crew surrogates 40-59 years of age were used. Small but statistically significant displacements occurred in symptoms and in some spirometry parameters. In general, the younger subjects appeared more sensitive to ozone than the older subjects. No significant differences appeared between smokers' and nonsmokers' responses to ozone exposure. It is concluded that the ozone threshold of these sedentary surrogates under these experimental conditions is right at 0.30 ppmv.

Effects of ozone on symptoms and cardiopulmonary function in a flight attendant surrogate population.

Two studies were conducted to ascertain the lowest ozone concentration threshold for statistically significant adverse effects on cardiopulmonary function and symptoms in male and female surrogates of the flight attendant population. Both studies simulated in-flight environmental conditions at 1,829 m mean sea level (MSL) chamber altitude. The ozone exposures were 0.2 parts per million by volume (ppmv) for 4 h in the first study and 0.3 ppmv for 3 h in the second study. Each subject was similarly exposed to air only (no ozone) on another occasion. Treadmill exercise, equivalent to workloads of on-duty flight attendants, was performed at altitude. Cardiorespiratory measurements were made during ozone exposure, whereas spirometry and symptom assessments were made immediately before and after exposure. The ozone threshold for reversible adverse effects on symptoms and spirometry function was reached by a 3-h exposure to 0.3 ppmv. The data suggest a greater symptomatic sensitivity to ozone in females.

Stress in air traffic personnel: low-density towers and flight service stations.

Stress and anxiety levels were measured in 10 air traffic control specialists (ATCS) at two low traffic-density towers in Fayetteville (FYV), Ar, and Roswell (ROW), NM, and in 24 flight service (FS) specialists at those airports and at Okalhoma City (OKC), Ok. Physiological measurements consisted of heart rate and urine biochemical analysis for 17-ketogenic steroids, epinephrine, and norepinephrine. On-duty arousal in ATCSs and FS specialists was evident both physiologically and psychologically; such arousal was within psychologically normal limits and was generally low physiologically compared to other air traffic control (ATC) facilities studied in the past. Physiological stress levels at these low-density towers and flight service stations were also low compared to other ATC facilities studied previously. Therefore, it is inappropriate to describe all air traffic control work, as is commonly done in the popular press, as unusually stressful. Such accounts in the popular press tend to deal with the exceptional, rather than with the typical, controller or facility.

Effects of ground trainer use on the anxiety of students in private pilot training.

The self-reported anxiety levels of student pilot instruction entirely in an aircraft were compared to the anxiety levels of students who received a portion of their training in a ground trainer. It was found that experience in the trainer had little effect on student pilot anxiety. It was determined, however, that reported anxiety levels did vary as a function of the type of flight (solo, dual, or evaluation) undertaken.

Stress in air traffic controllers: effects of ARTS-III.

Physiological, biochemical, and psychological assessments of stress in air traffic controllers were made at Los Angeles (LAX) and Oakland (OAK) Terminal Radar Approach Control (TRACON) facilities before and after installation of Automated Radar Terminal Systems-III (ARTS-III). Heart rates of controllers on duty or at rest scarcely changed from before to after ARTS-III installation. Total stress increased at both TRACONs, and the increase was entirely due to elevated catecholamine excretion. Steroid excretion was significantly reduced at both facilities after ARTS-III had no appreciable effect on work-related anxiety levels of controllers. The post-ARTS-III A-State means for both facilities were not significantly elevated. A-Trait was unchanged at LAX but decreased significantly at OAK. Assessments of A-State showed significant work-related increments but tended to be low. There were no correlations between anxiety and physiological data.

Effect of a general aviation trainer on the stress of flight training.

Sixteen students were given flight training according to a highly standardized and rigidly controlled 35-h syllabus. Eight of the group (TG) recieved 10 h of their training in a Link GAT-1 ground trainer and 25 h in a Cherokee 140B. the other eight (AG) recieved all of their training in the airplane. The resting heart rate (HR) of group TG was significantly lower when the ground trainer was to be used than was the resting HR of group AG on equivalent lessons. The difference disappeared when group TG was to fly the airpland. In flight, group AG'S HR was significantly higher than group TG's in the ground trainer. Again the difference disappeared when group TG flew the airpland. Physcial work, as indicated by O2 consumption, was greater in the airplane than in the ground trainer. Urine chemistry indicated only a few and inconsistent points of significant differece between the groups. However, pre- and post-flight differences showed highly significant differences for both TG and AG. Objective flight tests administered four times during the syllabus indicated insignigicant differences between TG and AG, likewise, a check pilot who did not know to which group a student belonged could not differentiate between groups TG and AG. It was concluded that 10 h training in the GAT-1 did not compromise the flying skill as judged by the check pilot.