Research Program Area: Health & Exposure
Topic Areas: Health Effects of Air Pollution
We extended our prior studies of nitrogen dioxide (NO2) and ozone (O3) effects on the mouse lung and immune system to nests of the ambient outdoor atmospheres of two communities, Los Angeles (LA) and Santa Barbara (SB). LA often exceeds ozone, nitrogen dioxide and other pollutant standards, whereas exceedences in Santa Barbara are relatively infrequent. Two additional animal groups were included in the comparisons. One group was maintained in an air conditioned vivarial room in LA and the other in the same room but in an environmental chamber having an air supply filtered for particulate and oxidants. During the 1985 summer test period, the LA test site exceeded the 1985 State ozone standard (0.1ppm O3 one-hour average; 1985 20 of the 43 days and had four O3 episodes ( > 0.2ppm), vs. two exceedences for Santa Barbara and no episodes. NO2 levels in LA did not exceed the 0.25 ppm one hour standard for California, but they averaged 0.1 ppm, and there were nine days when 0.15 ppm one hour maximal averages were reached or exceeded. The on-site 0 recordings were less due to partial "scrubbing" by the vivarial facility, but there were nevertheless five exceedences of the 1985 0.1 pmm O3 standard. Statistically significant differences in lung measurements were found between the LA and SB animals, including more and larger Type 2 Cells for the LA animals, thicker alveolar wails, increased elastic tissue, and an altered relationship of elastic fibers to the alveolar wail. All of the foregoing are common denominators and early events in many destructive diseases or the human lung. Their greater frequency in the lungs of the LA animals, compared to those of the Santa Barbara group, suggests that LA air pollution accelerates irreversible "wear and tear" injury to the lung, i.e. increases the rate of decline of lung structure and function. The long term effect is to reduce the Level of lung reserves. For the human population, an inordinate depletion of lung reserves will cause, promote, facilitate, and/or exacerbate clinical disease in general. The reserves of the immune system may also have been adversely affected. In particular, the LA animals had smaller spleens and lower percentages of splenic T lymphocytes than did the Santa Barbara animals. Some degree of immuno suppression of the LA animals is implied by the findings and this would further suggest some increase in susceptibility to disease in general. This report is submitted in fulfillment of ARB Contract A4-160-33, Effect of Ambient Air Pollution on the Lung and Immune System, by the Professional Staff Association under the sponsorship of the California Air Resources Board.
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