ozone toxicity symptoms among flight attendants

American Journal of Industrial Medicine 1:43-54 (1 980)

Ozone Toxicity Symptoms Among Flight Attendants Dwayne Reed, MD, PhD, Sally Glaser, MS, and John Kaldor, MA

Epidemiological Studies 1 aboratory Section, California State Department of Health Services, Berkeley

Because of persistent complaints of ozone-toxicity type symptoms among crew members of commercial airlines, we undertook a survey to determine the extent of the problem and the associated flight factors. Self-reported questionnaires and flight diaries were completed by 1,330 flight attendants, (FAs) working for three different airlines. Ozone-toxicity type symptoms were reported three or four times more frequently by FAs with airlines flying at high altitudes than by those with low-flying airlines. When examined by characteristics of flights, the ozone-toxicity type symptoms were significantly associated with flight altitude, duration and type of aircraft, but not with years worked, sex, medical history, or home residence. Other symptoms indicative of fatigue or stress were mainly associated with flight duration. While these indirect data cannot implicate ozone specifically, they offer evidence that ozone-related health problems do exist among a large proportion of FAs.

Key words: ozone toxicity, flight attendants, high-flying aircraft

INTRODUCTION

During 1976 and 1977 commercial airlines received hundreds of complaints from passangers and crew members describing serious physical symptoms including chest pain, shortness of breath, coughing, wheezing, and burning sensations in the throat and eyes [1] . Originally, these reports came from persons flying the new B-747-SP high altitude aircraft, but similar reports came later from persons on other high altitude aircraft. During this same period the NASA Global Atmospheric Sampling Program (GASP) had equipped several commercial aircraft with special equipment to measure atmospheric ozone, and when it was noted that high concentrations of atmospheric ozone correlated well with the reports of physical symptoms, ozone became the suspected cause of the symptoms.

often exceeded the limits for human exposure currently recommended by the Occupational Safety and Health Administration [2], and because of the persistent complaints of physical symptoms [3,4] we were requested in March, 1978, by the Independent Union of Flight Attendants, to investigate the extent of reported health problems among flight attendants ( F A ) and the factors associated with them.

Because it has been known for many years that ozone levels in commercial aircraft

Address rcprint requests to Dr. Dwayne Reed, Honolulu Heart Program, NHLBI, 347 North Kuakini Street, €Ionolulu, HI 9681 7.

0271-3586/8O/OlOl-0043$02.30 0 1980 Alan R. Liss, Inc.

44 Reed, Glaser, and Kaldor

Background

oxygen. The concentration of this gas increases gradually in the troposphere to about 1 ppm at 40,000 feet and then increases sharply in the stratosphere to a peak of over 10 ppm at 70,000 to 90,000 feet. Because of seasonal, latitudinal, and meteorological variations in the tropopause boundary between troposphere and stratosphere there are consider- able variations in ozone concentrations. In the northern hemisphere, the highest concentrations generally occur in the high latitudes during the spring months.

Ozone is an unstable oxidizing gas which has a potential to damage living tissue in proportion to concentration and duration of exposure. Studies of pulmonary function among exposed humans show a direct relationship between the concentration of ozone and both mechanical lung function and frequency of reported symptoms [S-1 11 . Exposure of healthy adult volunteers to levels of 0.25 ppm for two or more hours resulted in a small but consistent decrease in flow rates and increased airway resistance as measured by mid- maximal expiratory flow rate, forced expiratory volume, and forced vital capacity. These changes were accompanied by occasional complaints of cough and chest discomfort. A t levels of 0.75 ppm there was a significant decrease in mechanical lung function including increased airflow resistance, decreased transpulmonary pressure, and maximum lung volume. The symptoms reported at this level included shortness of breath, substernal chest pain, wheezing, cough, and mild nausea.

Explanations of the altered lung function point to constriction of small airways and decreased elastic recoil of the alveolar region. As recovery is only partial 24 hours after exposure, an inflammatory response is probably involved.

Laboratory studies of exposed animals have provided information about the morphological effects of ozone exposure [12-141. In general, the higher the concentration of ozone the more extensive the damage and the deeper the penetration of damage into the respiratory tract. The process starts with focal damage to the ciliated epithelial tissue lining the major airways, followed by hyperplastic proliferation of nonciliated cells and deposits of connective tissue on the walls of the bronchioles. The alveolar septa become swollen andindividual cells become vacuolized. When exposure in mice was extended to several months the damage included epithelial hyperplasia, rupture of endothelial lining of alveolar capillaries, emphysematous enlargement of the alveoli, and progressive metaplasia of tracheal mucosa.

In addition to the direct effects upon the respiratory system, ozone has been shown to affect human v isua l response or the brain at exposures of 0.2 to 1 .O ppm [ 151 ; to increase susceptibility to bacterial infections among animals exposed to 0.1 ppm [16, 171 ; to cause congenital abnormalities and neonatal deaths in mice [18] ; and to cause chromosomal abnormalities in human tissue culture cells [19]. Chromosomal studies of hamsters and of humans have also been reported but the results are conflicting [20,21]. It appears that ozone is mutagenic, but it is doubtful that these effects extend beyond the site of the injury.

of 0.1 ppm recommended for occupational exposure. As early as 1963 studies of flights made by U.S. airline companies using a variety of aircraft showed that ozone in excess of 0.1 ppm was encountered “a significant amount of time,” and that peak levels were as high as 0.35 to 0.4 ppm [2,22].

Ozone is formed in the atmosphere by the action of ultraviolet light on molecules of

The ozone concentration in the cabins of commercial aircraft often exceeds the limit

Ozone Toxicity 45

In 1973, Bischof monitored cabin levels of ozone on 14 polar flights between Seattle and Copenhagen or Bergen [23], Ozone levels in excess of 0.5 ppm were found during some of these flights with peaks of 0.8 ppm on one flight. The author estimated that a time-weighted average of 0.1 ppm would be exceeded about 75% of the time on polar flights in the spring.

between Amsterdam and Toronto [24]. During more than 50% of the flying time cabin ozone levels exceeded 0.2 ppm, with peak concentrations of about 0.6 ppm. In general, the cabin level was found to be 70% of the atmospheric level of ozone.

NASA GASP Program [25-271. Beginning in early 1977, simultaneous measurements of cabin and atmospheric ozone concentrations were made on routine commercial flights of B-747 and B-747-SP aircraft. Initial analysis indicated that on the average 82% of atmospheric ozone entered the cabin of the B-747-SP and 39% entered the B-747. On one B-747-SP flight, the cabin ozone level was greater than 0.4 ppm for over 2% hours. In general, the cabin ozone levels approached those of the atmosphere as the flight pro- gressed; that is, the longer the duration of the flight, the higher the cabin levels of ozone.

Preliminary tabulation of 197 flights made by the B-747-SP shows that the average cabin ozone level exceeded 0.1 ppm for 11 1 (58%) of the flights and that the maximum cabin levels exceeded 0.3 ppm on 11 8 (60%) and 0.5 ppm on 45 (23%) of the flights [27] .

Similar high levels of ozone were found in a recent study of a DC-10 round trip

The most extensive measurements of cabin ozone levels are those made by the

MATERIALS AND METHODS

In order to determine the extent of symptoms, and their association with the Characteristics of commercial flights, the study focused upon FAs working for three airlines which have different types of flights in regard to atmospheric ozone exposure. Pan American World Airways (PAN AM) usually flies long distances at high altitudes, Trans World Airlines (TWA) flies both long distances at high altitude and shorter, lower altitude flights, and Pacific Southwest Airlines (PSA) fhes only short duration, low altitude fights.

out a mailed questionnaire and a flight diary. The questionnaire included background information about demographic and occupational characteristics, history of medical problems, smoking habits, medication use, and flight-related symptoms during the previous year. The flight diary covered five flight-days and elicited information about each flight including the type of aircraft, flight duration, cruising altitude, and a check- list of symptoms experienced during and within 24 hours after each flight-day.

The list of symptoms included those usually reported after experimental exposure to ozone such as chest pain or tightness, and difficulty breathing. The symptoms of cough, burning eyes, and sore throat were included with the understanding that while they are reported after ozone exposure, they could also be related to low humidity and cigarette smoke in the aircraft cabin. For contrast we also included symptoms which could be related to exertion and stress from long working lmurs, time zone changes, turbulence or cabin pressurization. These included extreme fatigue, backache, pain in legs or feet, headache, neck pain or tightness, numb or tingling fingers, nausea or vomiting, nose bleeding, and dizziness or fainting.

FAs stationed on the West Coast were invited to participate in the study by filling

The questionnaires were mailed to 3,280 FAs thought to be on active status from


union records. Of these, 1,330 completed the questionnaire, 206 refused to participate, and 1,744 did not respond. In order to determine the reasons for not responding, we contacted a sample of 125 persons. Of these, 49% were on extended leave or had resigned, 14% had not received the questionnaire, and the remaining 37% were not interested in participating. From the results of this sample, we estimated that 61% of the FAs who were on active status completed the questionnaires, with little difference among the different airline groups.

Of the 1,330 FAs who completed the questionnaire, 1,080 were on active flying status during the months of April and May, 1978 - the time period for which we requested completion of the diaries. These FAs reported information for a total of 5,074 flight-days (an average of 4.7 per person). When required in the analysis, age adjustment (based upon the total study population) and standardization of rates for altitude or duration were performed using the direct method of adjustment. Estimated variances of the adjusted rates were obtained by considering the category-specific rates as binomial ran- dom variables, and 95% confidence intervals were constructed using the normal approximation. Differences in rates were considered statistically significant when the 95% confidence intervals did not overlap for rates based upon individuals, and when the 99% confidence intervals did not overlap for rates based upon flight-day data.

A multiple logistic analysis was used to examine the statistical relationship of reported symptoms with individual variables independent of the effect of other variables. The data in this analysis were taken from the flight diaries, and in addition to a positive or negative response to the symptoms under consideration, measures of each of the following risk variables were included: age of the FA making the flight, current smoking status, maximum cruising altitude of the aircraft (in thousands of feet), duration of the flight (in hours), type of aircraft (B-747, B-747-SP, LlOll, B-707 coded categorically, relative to the B-727), and home base of the FA.

For each flight-day, the risk R of a symptom in an individual was modeled as:

-(Bo + BlXl . . . . BkXk) R = 1/(1 + e )

where Bo . . . Bk are the k + 1 logistic coefficients in the model for the symptom, and Xi . . . X, are the levels of the factors described above for that person flight-day.

For each symptom, the coefficients were estimated by the maximum likelihood method using an iterative procedure for solving the maximum likelihood equations as programmed for computer by Brand and Sholtz [ 2 8 ] . For each coefficient, a test based on the asymptotic normality of coefficient estimates provided a significance level for the test that the coefficient is equal to zero; that is, that the corresponding risk variable had no independent effect on the risk of the symptom.

as it is not necessarily valid that the outcomes for different flights made by the same individual are independent. If these outcomes are not independent, but are treated as such, then the sample size and thus the statistical significance would be artificially inflated. On the grounds that although the standard errors of the coefficients may be artificially small, the coefficients and their relative significance levels would probably not be biased, we decided to use a conservative level of significance (p < 0.01) to judge the strength of the relationships.

There is a statistical problem involved in using this method of maximum likelihood,

Ozone Toxicity 47

RESULTS

The numbers of FAs who completed the questionnaire are shown in Table I by age and airline. Over 95% were female, and 92% were white. As separate analysis showed little difference in symptoms by sex and e t h i c group, these factors were not considered in subsequent analyses. There were no significant differences among the airline groups for llistory of prior serious medical problems including cardiovascular, respiratory, and aller- gic diseases, nor for smoking habits, or current medication use except that the FAs with PAN AM and TWA reported using sleeping pills more frequently than did those with PSA.

Table I1 shows the age-adjusted percentages of FAs who reported flight-related symptoms during the 12 months prior to the survey, by airline. There were clear differences among the airlines for the ozone-toxicity type symptoms with a gradient of the

TABLE I. Numbers of Flight Attendants by Age and Airline

Airline Age PAN AM TWA PSA Total

20-24 yr 0 5 69 74 25-29 yr 79 183 1 04 366 30-34 YI 289 274 42 605 35 + yr 145 119 4 268 unknown 7 8 2 17

Total 5 20 589 221 1,330

TABLE 11. Age-Adjusted Percentages of Flight Attendants Reporting Flight-Related Symptoms During the Past Twelve Months, by Airlines

Airline

PAN AM ‘WA PSA Total Symptoms n = 513” n = 581a n = 219a n = 1,330

Chest pain or tightness 64% 34 * 16* 44 Difficulty breathing 59* 42* 25 * 48 Persistent cough 42* 28* 27 34 Sore or dry throat 75 74 67 75 Nose bleeding 21* 12* 11 16 Eye problems 57 56 67 60 Extreme fatigue 86 83 78 85 Backache 65 69 64 69 Extreme leg pain 44 * 52 61* 53 Frequent headaches 47 50 48 50 Neck pain or tightness 52 59 52 57 Numb or tingling fingers 19 22* 9* 20 Nausea or vomiting 20 28 21 25 Ear pain 35* 56 59* 48 Dizziness 33 36 32 35

”Does not include flight attendants of unknown age. *Differences of frequencies are statistically significant at P = 0.05.


rates being highest for PAN AM, intermediate for TWA, and lowest for PSA. The differences for chest pain, difficulty breathing and persistent cough were statistically significant at the 0.05 level, as indicated.

In contrast, there was little difference among the airline groups for symptoms of extreme fatigue, backache, headache, or neck pain. Ear pain and extreme leg pain were reported significantly more frequently by FAs with PSA than by those with PAN AM.

Separate analysis of symptom frequencies by cigarette smoking status indicated that the symptoms of chest pain, difficulty breathing, persistent cough, burning eyes, and frequent headaches were reported 5%8% more frequently by nonsmokers than smokers. We also analyzed the frequencies of reported symptoms by area of residence, number of years worked as an FA, and past history of allergies, cardiac or respiratory disease, and found no meaningful differences. Finally, we examined the frequencies of upper respiratory infections by airline and found no significant differences.

The next step of the analysis focused on the flight diaries in order to examine the relationship between symptoms and the charactersitics of flights during which symptoms occurred. Initial tabulation by airline company showed symptom patterns similar to those described above; namely, that chest pain, difficulty breathing, persistent cough and nose bleeding were reported two to three times more frequently by FAs with PAN AM than by those with PSA, while those with TWA reported intermediate rates. There were no significant differences for the other symptoms except that extreme leg pain and b u m g eyes were reported most frequently by FAs with PSA.

Altitude and duration of flight are two of the major determinants of aircraft cabin ozone levels, but these two variables are strongly related to each other. We, therefore, used the direct method of adjustment to control the effect of one while examining the other. Table I11 shows the percentages of fhght-days during which symptoms were re-

TABLE 111. Percentages of Flight Days During Which Symptoms Were Reported by Maximum Cruising Altitude, Adjusted for Flight Duration

Cruising altitude

Symptoms <34,999 35,000-38,999 39,000 + Total n = 1,074a n = 2,356a n = 1,15Sa n = 5,074

Chest pain or tightness Difficulty breathing Persistent cough Sore or dry throat Nose bleeding Burning eyes Extreme fatigue Backache Extreme leg pain Headache Neck pain or tightness Numb or tingling fingers Nausea or vomiting Dizziness or fainting

12* 14* 17 26

3 54 45 * 26 48** 29 22

3 14 12

14* 14* 15 22

5 50 47 26 40* 28 * 23 4

11 1 o*

23** 25** 20 27

5 54 51** 32 44 35** 27 7

15 17**

15 17 17 25 4

51 48 28 43 30 24

5 13 12

aDoes not include unknowns. **, *Rates with double asterisks are significantly different from those with single asterisks at P < 0.01.

Ozone Toxicity 49

ported by maximum cruising altitude, adjusted for flight duration, and Table IV shows the percentages by flight duration, adjusted for altitude.

Among the ozone-toxicity type symptoms, both chest pain and difficulty breathing increased significantly in the highest altitude category. Among the other symptoms, fatigue, headache, and dizziness or fainting increased with altitude, while leg pain was significantly higher at lower altitudes.

When examined by flight duration all of the symptoms except neck pain, nausea or vomiting, and dizziness or fainting increased with duration of flight. There were different patterns, however, as the ozone-toxicity type symptoms were significantly lugher in only the longest duration category, while symptoms such as fatigue, backache, and leg pain were significantly higher in the duration categories of four hours or greater.

As the NASA GASP data indicated cabin ozone level differences between the B-747-SP and the B-747, we also examined the frequency of symptoms reported in the flight diaries by type of aircraft as shown in Table V. As some types of aircraft are usually flown at different altitudes than others, the percentages were adjusted for altitude using the maximum cruising altitude distribution of all 5,074 flight days as a standard. Of the symptoms indicating respiratory tract irritation, all but sore throat followed a pattern of being highest on the B-747-SP and B-747 and lower on the other aircraft. Asterisks indicate those rates which are significantly higher than rates for the €3-727. There were no significant differences among the other reported symptoms except for burning eyes and extreme leg or foot pain which were highest on the 727.

We also examined the percentages of reported symptoms by smoking status, home residence within each airline, years worked as a FA, and medical history of allergies, cardiovascular or respiratory disease and found no meaningful differences except that nonsmokers had slightly higher frequencies of chest pain, difficulty breathing, persistent cough, and burning eyes than did smokers.

TABLE IV. Percentages of Flight Days During Which Symptoms Were Reported, by Flight Duration, Adjusted for Altitude

Duration in hours

1-3 4-6 7-9 10-24 Total Symptoms n = 642a n = 2,393a n = 834" n = 715a n = 5,074

Chest pain or tightness 10* 12" 18* 32** 15

Sore or dry throat 19* 23* 21 32** 25 Nose bleeding 3* 3* I** 9** 4 Burning Eyes 39* 53** 55** 59** 51

Extreme leg pain 28* 45** 46** 41** 43

Numb or tingling fingers 3* 4 4 8** 5

Dizziness or fainting 9 11 13 16 12

Difficulty breathing 9* 15* 19* 31** 17 Persistent cough 15* 14* 19 26** 17

Extreme fatigue 34 * 44** 57** 62** 48 Backache 19* 28** 29** 33** 28

Headache 23* 29 33** 37** 30 Neck pain or tightness 18 24 23 28 24

Nausea or vomiting 10 13 13 15 13

aDoes not include unknowns **, *Rates with double asterisks are significantly different from those with single asterisks at P < 0.01.


TABLE V. Percentages of Flight Days on Which Symptoms Were Reported by Type of Aircraft, Adjusted for Altitude

Type of aircraft

B-747-SP B-747 B-707 1011 B-727 Total Symptoms n = 446a n = 1,377a n = 878a n = 832a n = 1,118a n = 5,074

Chest pain 26* 20* 12 13 10 15 Difficulty breathing 26 * 19* 17 14 12 17 Persistent cough 24 * 20* 14 14 11 17 Sore or dry throat 26 22 23 23 26 25 Nose bleeding 9* 6* 3 3 1 4 Burning eyes 47 42 50 52 62 51 Extreme fatigue 55 46 46 48 48 48 Backache 38 24 24 29 30 28 Extreme leg pain 42 36 40 44 51 43 Headache 34 28 29 30 27 30 Neck pain or tightness 22 21 21 25 26 24 Numb or tingling fingers 5 4 5 4 4 5 Nausea or vomiting 13 10 14 11 15 1 3 Dizziness or fainting 16 I 1 12 10 9 12

aDoes not include unknowns. *Percentages are significantly higher than rates for the B-727 at P < 0.01.

The final step of the analysis was to employ the multiple logistic analysis. After excluding records with missing values, a total of 4,414 flight-days were used in the analysis. Table VI shows those variables which were associated with each symptom independently of the effects of other variables. The odds ratio associated with a change of one standard deviation in the risk variable is also shown. The standard deviations were approximately five years for age, three hours for flight duration, and 3,600 feet for altitude.

The results of this analysis add strength to the patterns of association among the symptoms and risk factors shown in the preceding tables. For the ozone-toxicity type symptoms, both altitude and duration of flight were independently associated with chest pain, difficulty breathing, and burning eyes, while the B747 or B-747-SP were associated with chest pain and persistent cough. The odds ratios indicate that the reported frequencies of chest pain and difficulty breathing increased by about 50% for every three-hour increase in flight duration, and about 30%-40% for every increase of 3,600 feet altitude.

Duration of flight was consistently associated with the other symptoms. Cigarette smoking was significantly associated with leg pain, neck pain, and numb or tingling fingers, while not smoking was associated with difficulty breathing, sore throat, and burning eyes.

This latter finding is consistent with experimental findings which have been inter- preted as showing that smokers have decreased sensitivity to respiratory tract irritation [29].

DISCUSSION

The results of this study indicate that a large proportion of FAs experienced a variety of symptoms which were related to characteristics of the commercial flights that they were making. The symptoms indicative of respiratory tract irritation, and

Ozone Toxicity 51

TABLE VI. Results of Multiple Logistic Analysis of Variables Independently Associated with Reported Symptoms

Associated variables Odds ratio Symptom ~

Chest pain or tightness Duration p < 0.001 1.5 Altitude p < 0.001 1.4 B-747-SP p < 0.001 1.3 B-747 p = 0.009 1.3

Difficulty breathing Duration p < 0.001 1.5 Altitude p < 0.001 1.3 Nonsmoking p < 0.001 1.2

Persistent cough Duration p < 0.001 1.3 B-747-SP p < 0.001 1.3 Age p < 0.001 1.2

Sore or dry throat Duration p < 0.001 1.4 Nonsmoking p = 0.003 1.1

Nose bleeding B-747 p = 0.004 1.8 B-747-SP p = 0.005 1.5

Altitude p < 0.001 1.2 Nonsmoking p < 0.001 1.2

Duration p < 0.001 1.4 Burning eyes Duration p < 0.001 1.6

Extreme fatigue Duration p < 0.001 1.7 Backache Duration p < 0.001 1.3 Extrenie leg pain Duration p < 0.001 1.4

Smoking p < 0.001 1.4 Headache Duration p < 0.001 1.3 Neck pain or tightness Duration p < 0.001 1.3

Smoking p = 0.004 1.1 Numb or tingling fingers Age p < 0.001 1.4

Duration p = 0.001 1.3 Smoking p = 0.001 1.2

Nausea Duration p < 0.001 1.3 Dizziness Duration p < 0.001 1.4

B-707 p < 0.001 1.4

consistent with ozone toxicity, were reported at a two-to fourfold higher frequency by FAs with airlines which fly high altitude, long distance flights than by FAs with an airline which fhes low altitude, short duration flights. When examined by characteristics of current flights during April and May 1978, these symptoms were significantly related to altitude, duration of flight and type of aircraft, but not to other characteristics including sex, years worked, past medical history, or home base.

A major limitation of this study is the lack of in-cabin measures of ozone concentrations and other characteristics of the cabin air. As we were not permitted to do any in-cabin monitoring, we were left with the indirect measures. While this approach is less than ideal for approximation of ozone levels, it is supported by the fact that altitude and duration have been established as strong indicators of cabin ozone concentrations [25,26].

Other factors which could contribute to reported symptoms include in-cabin carbon monoxide (CO), low relative humidity, and cabin pressurization. Prolonged exposure to CO at 0.05% can cause headaches, dizziness, nausea, and visual disturbances,


but two separate tests of cabin air in DC-8, DC-10, and B-747-SP aircraft indicated that CO never reached levels which could cause symptoms [30,31]. Cabin air pressurization may produce partial pressures of oxygen equivalent to altitudes of 3,000-7,000 feet, but in tests made during six flights of DC-8 and DC-I0 aircraft, the partial pressure of oxygen never reached a level which would affect performance of crew members [30] . In addition, pressurization is relatively stable and would not produce the gradient of reported symptoms at different altitudes.

Average relative humidity levels have been reported as 14% on B-747-SP and 12% on DC-8 and DC-10 aircraft [30,31]. These levels could lead to dehydration of mucous membrane and cause nasal and throat dryness and burning eyes, but Bischof s study of 14 polar flights showed that symptoms of eye and respiratory tract irritation were correlated with cabin ozone levels, but not with relative humidty 1231.

A potential source of bias in this study was the use of self-reported symptoms among a group representing about 61% of invited participants. It is possible that some selection process favored those who were more sensitive to cabin conditions, or who were more prone to complain for various reasons. While such a bias could increase the magnitude of reported symptoms, it is unlikely that it could account for the consistent patterns of association. The associations between the ozone-toxicity type symptoms and the indirect measures of ozone exposure were strong and statistically significant whether viewed from comparisons of the different airlines or from the dose-response type patterns of altitude and flight duration. Furthermore, these patterns of association were specific for the ozone-toxicity type symptoms, especially chest pain or tightness and difficulty breathing, but not for other symptoms such as backache, neck pain, and fatigue. Symptoms of chest pain and difficulty breathing also increased consistently with altitude in every category of duration, a dose-response pattern which would be unlikely to occur artificially. After adjustment for the effects of altitude and duration, certain types of aircraft were associated with higher rates of ozone-exposure type symptoms, a finding which is consistent with the NASA GASP data which was unknown during the study period [26,27].

Thus, there is a general pattern indicating that ozone-toxicity type symptoms increase with increasing estimated measures of exposure. While these indirect data cannot implicate ozone specifically, they do offer evidence that an ozone-related health problem does exist, and that this problem should receive more direct attention, especially since the effects of chronic ozone exposure among humans are generally unknown.

In February 1980, the Federal Aviation Administration issued a new regulation to limit ozone concentrations in airplanes to a 0.1 ppm time-weighted average, with a maximum of 0.25 ppm effective as of February, 1981. However, compliance with this regulation does not require the mandatory use of onboard ozone sensors.

ACKNOWLEDGMENTS

Carmen Azzopardi, Director of Health and Safety, Independent Union of Flight Attendants, collected health reports and brought the seriousness of the problem to the attention of several Federal and State agencies. Without her continuing help and that of the other union representatives for PAN AM, TWA, and PSA this study could not have been undertaken. We are also grateful to Dr. Philip Landrigan, National Institute for Occupational Safety and Health for his continued support of this study, to Verne Nelson

Ozone Toxicity 53

for his contributions to the data analysis, and to Paul Ostroy, M.D., Center for Disease Control, Atlanta, Georgia for his consultation and help with this study.

REFERENCES

1. Carley W: A new danger alert for air travelers: Ozone-gas sickness. The Wall Street Journal, p 1, May 5 , 1977.

2. Jaffe L, Estes 11: Ozone toxicity in cabins of high altitude aircraft ~ A review and current program. Aerospace Medicine 34:633-643, 1963.

3. Hint I : Pan Am continues to get complaints about ozone illness. The New York Times, p A23, February 15, 1978.

4. Carley W: Ma1 d’air: Ozone illness returns on some airline flights, and the FAA prepares to issue first regulations. The Wall Street Journal, p 40, March 28, 1978.

5. Final report of the summary statement from the advisory panel on health effects of photochemical oxidants. EPA Report, June, 1977.

6. Von Nieding G, Wagner M, Lollgen H, Krekeler H: Zur akuten wirkung von ozon auf die lungen- funktion dcs menschen. Proceedings of the VDI Commission Colloquium on Ozone and Related Substances in Photochemical Smog. VUI Keport No. 270, pp 123-129, 1977.

7. Hackney J, Linn W, Law I), Karuza S, Greenberg H, Buckley R, Pedersen E: Experimental studies on human health effects of air pollutants. 111. Two-hour exposure to ozone alone and in combina- tion with other pollutant gases. Arch Environ Health 30:385-390, 1975.

8. Hazucha M, Silverman F, Parent C, Field S, Bates D: Pulmonary function in man after short-term exposure to ozone. Arch Environ Health 27:183-188, 1973.

9. Bates D, Hazucha M: The short-term effects of ozone on the human lung. In National Academy of Sciences, Proceedings of the Conference on Health Effects of Air Pollutants, October 3-5, 1973. Senate Committee on Public Works, Print Serial No. 93-15. Washington D.C.: U.S. Govern- ment Printing Office, pp 507- 540, 1973.

10. Bennett G : Ozone contamination of high altitude aircarft cabins. Aerospace Med 33:969-973, 1962.

11. Goldsmith J, Nadel J: Experimental exposure of human subjects to ozone. J Air Poll Control Assoc 19:329-330, 1969.

12. Schwartz L, Dungworth D, Mustafa M, Tarkington B, Tyler W: Pulmonary response of rats to ambient levels of ozone. Lab Invest 34:565-578, 1976.

13. Schlipkiiter H, Bruch J: Functional and morphological alterations caused by exposure to ozone. Zentralbl Bakteriol (Orig. B.), 156:486-499, 1973.

14. Bruch J , Schlipkoter H: Changes in the pulmonary alveoli in mouse following chronic exposure to a low concentration of ozone. Virchows Arch [Pathol Anat] 358:355-368, 1973.

15. Lagerwerff J : Prolonged ozone inhalation and its effects on visual parameters. Aerospace Medicine 34:479-486, 1963.

16. Ehrlich R, Findlay J , Fenters J, Gardner D: Health effects of short-term exposures to N02-03 mixtures. Proceedings of the International Conference on Photochemical Oxidant Pollution and its Control. Raleigh, N.C., EPA Publication #EPA-600/3-77-0016, pp 565-575, 1976.

17. Goldstein E, Tyler W, Hoeprich D, Eagle C: Ozone and the antibacterial defense mechanisms of the murine lung. Arch Intern Med 127:1099-1102, 1971.

18. Veninga T: Toxicity of ozone in comparison with ioniLing radiation. Strahlentherapie (Munich) 134:469-477,1967.

19. Fetner R: Ozone-induced chromosome breakage in human cell cultures. Nature 194:793-794, 1962.

20. Zelac R, Cromoy H, Bolch W, Dunavent B, Bevis H: Inhaled ozone as a mutagen. I. Chromosome aberrations induced in Chinese hamster lymphocytes. Environ Res 4: 262-282, 1971.

21. Marz T, Render M, Kerr H, Kulle T: Observations of aberrations in chromosomes of lymphocytes from human subjects exposed to ozone a t concentrations of 0.5 ppm for 6 and 10 hours. Mutat Res 31:299-302, 1975.

22. Brabets R: Ozone measurement survey in commercial jet aircraft. Federal Aviation Agency Technical Keport AD-5, 1963.


23. Bischof W: Ozone measurements on jet airline cabin air. Water Air and Soil Pollution 2:3-14, 1973.

24. Van Heusden S, Mans L: Alternating measurement of ambient and cabin ozone concentrations in commercial jet aircraft. Aviat Space, Environ Med 49:1056-1061, 1978.

25. Aircraft cabin ozone measurements determined from NASA Global Atmospheric Sampling Program on B-747 and B-747-SP aircraft. NASA Memorandum, 1978.

26. Perkins P, Briehl P: Simultaneous measurements of ozone outside and inside cabins of two B-747 airliners and a Gates Learjet business jet. NASA Technical Memorandum 78983, 1978.

27. Holdeman J , Dudzinksi T, Tiefermann M, Nyland T: NASA GASP data report for tapes VLOOlO and VLOOl2. NASA Technical Memorandum 79061, 1979.

28. Brand R, Sholtz R: DISCL computer program. Berkeley, CaIifornia: University of California, School of Public Health, 1978.

29. Kerr H, Kulle T, MCIlhdny M, Swidersky P: Effect of ozone on pulmonary function in normal subjects. Am Rev Respir Dist 111:763-773, 1975.

30. Vieillefond H, Fourn P, Auffret R: Characteristics in the atmosphere of long-range transport aircraft cabins. Aviat Space Environ Med 48:503-507, 1977.

31. Air conditioning tests during revenue flights. Boeing Document T6-4453.

ozone toxicity symptoms among flight attendants

Documents