ABSTRACT

Background: The effects of air pollution on the respiratory system is a topic of large concern. Most of the studies dealing with the relationship between air pollution and pulmonary function -estimated through spirometry- have been performed by appliying linear regression analysis. This study is based on canonical correlation, in order to relate a set of spyrometric variables to a set of pollutant variables. Material and methods: 307 schoolchildren (144 boys, 47%, and 163 girls, 53%) from the five regions of the metropolitan area of Mexico City were studied in six different seasons, three in 1995 and three in 1996. Twelve spirometric variables were measured on every child every season in order to be related to 20 pollution variables including the daily maximum concentrations of O3, NOj, SO,, CO and PM l0 measured the day of the spyrometry (time 0), 24, 48 and 72 hours before. The statistical independent or explanatory variables are the pollution variables and the statistical dependent or response variables are those of spirometry. The strength of the association was based on the first canonical correlation coefficient and considered when its absolute value was greater than or equal to 0.3 in the case of the analysis by region and greater than or equal to 0.28 in the case of the analysis by seasons. The results will be presented from the highest canonical correlation coefficient to the lowest one. It will be described what happened when one or more pollutants increase considering that other pollutants decrease and that the converse produced the opposite effect. Further, the decrease of one o more pollutants allows the pollutant with exceeding concentration to produce the strongest effect. Results: O3 and PM)0 exceeded the standard during the study. A) Boys. In region 1 when PM1O48, PM100, PM1024 and NO272 increase FEF25, PIF, FEF^, FEFmMso and ET decrease; in region 5 when NO20 increases ET and MTT increase and FIF__ _ and I VC decrease; in season 1 when O348, NO 48 and NO 72 increase FVC, FEV,, FEF^, PEF, FEF^ and FEF decrease; in season 2 when 0,72 and 0,0 increase FEV,, FVC, FEF^,, PEF, PIF and FEF_„^ decrease; in season 3 when 0,48 increases PIF decreases; in season 4 when 0,72 and 0,48 increase I VC decreases but PEF increases; in season 5 when SO,72 and SO,48 increase IVC increases also; in season 6 when 0,0 increases ET and IVC increase and PIF and FIFM^, decrease. B) Girls. In region 1 when NO,72 increases PIF, PEF, FEF7S and FEF^, decrease and ET increases; in region 2 when NO,24, NO,48 and NO,72 increase PIF decreases; in region 3 when 0,24 and 0,48 increase ET increases; in region 4 when SO,48 and NO,24 increase ET decreases; in region5 when NO,24 and SO,48 increase PIF, FIF^,, and PEF decrease; En season 1 when NO,48 increases ET, MTT and FVC increase and FEF7$ decreases; in season 2 when 0,24, NO,72,0,0,0,72 and 0,48 increase FVC, FEV, FEF^and PEF decrease; in season 3 there were not significant correlation between both sets of variables; in season 4 when 0,48 increases PEF, FEF,,,, FEV, and FVC decrease; in season 5 when 0,0 and 0,48 increase IVC, ET, PEF, FVC and PIF decreases; in season 6 when NO272, NO,24, NO,0 and NO248 increase ET but FVC decrease. Conclusions: The mix of pollutants affects boys different from girls. The effect of PM„, NO, and SO, is stronger when the region is considered and that of O, appears to be more related to the season. Pollutants affect together and not individually and also the effect of their current concentration does not appear to be stronger than those of the previous days. Neither a single pollutant affects pulmonary function by itself nor a single spyrometric variable responds alone.

KEYWORDS

air pollution, spirometry, metropolitan area of Mexico City.

REFERENCES

1. Spektor DM, Lippmann M, Lioy PJ, Thurston GD, Citak K,James DJ, et al. Effects of ambient ozone on respiratoryfunction in active normal children. Am Rev Respir Dis1988;137:313-20.

2. Goren AL, Hellman S, Brenner S, Egoz N, Rishpon S.Prevalence of respiratory conditions among schoolchildrenexposed to different levels of air pollutants in the Haifa Bayarea, Israel. Environ Health Perspect 1990;89:225-31.

3. Higgins IT, D'Arcy JB, Gibbons DI, Avol EL, Gross KB. Effectsof exposure to ambient ozone on ventilatory lung function inchildren. Am Rev Respir Dis 1990;141(5):1136-46.

4. Berry M, Lioy PJ, Gelperin K, Buckler G, Klotz J. Accumulatedexposure to ozone and measurement of health effects inchildren and counselors at two summer camps. Environ Res1991;54:135-50.

5. Spektor DM, Hofmeister VA, Artaxo P, et al. Effects of heavyindustrial pollution on respiratory function in the children ofCubatao, Brazil: A preliminary report. Environ Health Perspect1991;94:51-54.

6. Castillejos M, Gold DR, Dockery D, Tosteson T, Baum T,Speizer FE. Effects of ambient ozone on respiratory functionand symptoms in Mexico City schoolchildren. Am Rev RespirDis 1992;145(2):276-82.

7. Castillejos M, Gold DR, Damokosh Al, et al. Acute effects ofozone on the pulmonary function of exercising schoolchildrenfrom Mexico City. Am J Respir Crit Care Med 1995;152(5):1501-7.

8. Kinney PL, Thurston GD, Raizenne M. The effects of ambientozone on lung function in children: A reanalysis of six summercamp studies. Environ Health Perspect 1996;104:170-4.

9. Scarlett JF, Abbott KJ, Peacock JL, Strachan DP, AndersonHR. Acute effects of summer air pollution on respiratoryfunction in primary schoolchildren in southern England. Thorax1996;51(11):1109-14.

10. Ulmer C, Kopp M, Lhorst G, Frischer T, Forster J, Kuehr J.Effects of ambient ozone exposure during the spring andsummer of 1994 on pulmonary function of schoolchildren.Pediatr Pulmonol 1997;23(5):344-53.

11. Dodge R, Solomon P, Moyers J, Hayes C. A longitudinal studyof children exposed to sulfur oxides. Am J Epidemiol1985;121(5):720-36.

12. Raizenne ME, Burnett RT, Stern B, Franklin CA, SpenglerJD. Acute lung function responses to ambient acid aerosolexposure in children. Environ Health Perspect 1989;79:179-85.

13. Spektor DM, Thurston GD, Mao J, He D, Hayes C, LippmannM. Effects of single- and multiday ozone exposures onrespiratory function in active normal children. Environ Res1991;55(2):107-22.

14. Stern B, Raizenne ME, Burnett RT, Jones L, Karney J,Franklin CA. Air pollution and childhood respiratory health:Exposure to sulfate and ozone in 10 Canadian ruralcommunities. Environ Res 1994;66:125-42.

15. Studnicka MJ, Frischer T, Meinert R, el al. Acidic particles andlung function in children. A summer camp study in the AustrianAlps. Am J Respir Crit Care Med 1995;151(2):423-30.

16. Linn WS, Shamoo DA, Anderson KR, et al. Short-term airpollution exposures and responses in Los Angeles areaschoolchildren. J Exp Anal Environ Epidemiol 1996;6(4):449-72.

17. Muñoz BB. índices de la contaminación ambiental. NeumolCir Tórax 1997;56:48-57.

18. American Thoracic Society. Standardization ot spirometry.Respiratory Care 1987;32:1039-60.

19. Taussig LM, Chernick V, Wood R, Farrell P, Mellins RB.Standardization of lung function testing in children. JPediatrics 1980;97(4):668-76.

20. Johnson RA, Wiehern DW. Canonical correlation analysis.In: Applied multivariate statistical analysis. USA: PrenticeHall, 1992:459-92.

21. Gnanadesikan R. Development of multivariate dependencies.In: Methods for statistical data analysis of multivariateobservations. USA: John Wiley & Sons, 1997:62-80.

22. Bascom R, Bromberg PA, Costa D A, el al. Health effectsof outdoor air pollution. Am J Respir Crit Care Med1996;153:3-50.

23. Quanjer PH, Stocks J, Polgar G, Wise M, Karlberg J,Borsboom G. Compilation of reference values for lungfunction measurements in children. Eur Respir J 1989;2(suppl 4):184s-261s.