Effect of Exposures to Ambient Ozone on Ventilatory Lung Function in Children

Abstract

This study was undertaken to determine if the ventilatory capacity of children is affected by hourly concentrations of ozone inhaled during their daily activity. Over a 3-wk period (June-July 1987) children who were attending a summer camp in the San Bernardino mountains of California performed spirometry up to three times per day during their stay at the camp. A total of 43 children were tested a total of 461 times. Ozone, oxides of nitrogen, sulfur dioxide, temperature, and relative humidity were measured continuously. Daily average measurements of total suspended particulate and the PM10 particulate fraction (less than or equal to 10 microns) were also made. Hourly ozone concentrations at the time of testing varied between 20 and 245 ppb. Regressions of each individual's FEV1 and FVC supported the view that high ozone levels reduced these lung function parameters. The average regression coefficient for FEV1 on ozone was -0.39 ml/ppb (SEM = 0.12) and for FVC -0.44 ml/ppb (SEM = 0.15), both of which were significantly different from zero. Statistical allowance for temperature and humidity increased the magnitude of these slopes. Nitrogen dioxide never exceeded 40 ppb during the time of testing and averaged 13 ppb. Sulfur dioxide's highest measurement was 8 ppb and often was at the limit of detection. Neither NO2 nor SO2 was considered in the statistical modeling. Data were divided based on whether each subject had been exposed to levels of ozone in excess of the National Ambient Air Quality Standard (NAAQS) during the several hours previous to being tested. Exposures exceeding the NAAQS indicated a significant negative relationship between ozone and FEV1, FVC, and PEFR. Data for nonexceedance periods did not indicate this negative relationship for any of the three lung function parameters, but it could not be determined if this was due to an absence of an ozone effect or to a combination of the increased variability and decreased size of this data subset. These data indicate that lung function changes on a daily basis relate in a negative fashion to ambient ozone levels. The magnitude of the changes are small and are reversed as ambient ozone decreases.

Association of Ambient Ozone Exposure with Airway Inflammation and Allergy in Adults with Asthma

“…Atopy did not play a significant role in any associations except for exhaled NO levels. A reasonable conclusion is that even if smaller groups are evaluated in such translational exposure studies, real-world ozone levels did demonstrate biologically and scientifically plausible associations, underscoring other investigators' premise that controlled chamber studies likely underestimate the effects of true outdoor air pollutants (11,17). Ambient posted monitors have been used thus far to evaluate lung health and ozone levels (20,50).…”

“…Large cohort studies have demonstrated worsening of lung function, i.e., decrement in morning peak flow rates or small airways function, in the days after elevated atmospheric ozone levels (8,10). Although asthmatics are particularly susceptible to the harmful effects of ozone air pollution, controlled exposure chamber studies demonstrated acutely diminished lung function in asthmatics as well as healthy individuals after being exposed to high concentrations of ozone (11)(12)(13). The capacity to induce pulmonary function alterations depends on ozone levels, duration and pattern of exposure, and respiratory minute volume (14).…”

“…Although epidemiologic and chamber protocol studies have explored the mechanisms underlying these associations, some investigators believe that ozone-associated changes in pulmonary function are greater in natural than in controlled exposure settings (11,17). Studies of children and adults in natural ozone environments have demonstrated a dose-response relationship between ambient ozone levels, asthma symptoms, and worse lung function; however, the mechanisms responsible remain poorly understood (18)(19)(20)(21)(22).…”

The Effects of Ambient Ozone on Lung Function in Children: A Reanalysis of Six Summer Camp Studies

“…McDonnell and colleagues (5) This article presents the results of our reanalysis of the original lung function and 03 data from six recent summer camp studies. These studies indude two in northwestern New Jersey (3,11), two in southern California (6,9), and two in Ontario (8,12 The Lake Couchiching study was conducted collaboratively by Health and Welfare Canada and Harvard University over 10 days in late June and early July of 1983 (7,12). Lung function data were collected twice daily (0730-0930 hr and 1630-1830 hr) for 52 campers (including 23 asthmatics: 12 males and 11 females, and 29 nonasthmatics: 16 males and 13 females), who ranged from 7 to 15 years of age.…”

“…The first took place at a church-sponsored summer camp in the San Bernardino Mountains (elevation 1740 m) (6 Working data sets for each study reviewed above were obtained either directly from members of the original study teams, or through third parties (see Acknowledgments). A common feature of all six data sets was the availability of afternoon spirometric lung function data collected over many days on many subjects, along with the previous 1-hr average 03 concentrations.…”