Page 485 - Environment: The Science Behind the Stories

tHe SCieNCe beHiNd tHe StOry

Measuring the children from 39 Mexico City schools
Health impacts of across 3 years and correlated this
with their exposure to tropospheric
Mexico City’s ozone, nitrogen dioxide, and par-
Air Pollution ticulate matter. The children’s ability to
inhale and exhale deeply improved as
“I know I’m inhaling poison,” a 38-year- they matured, but children from more
old candy vendor named Guadalupe polluted areas lagged behind those
told a reporter amid the fumes of a from cleaner areas, indicating smaller,
traffic-choked intersection in Mexico weaker lungs.
City. “But there is nothing I can do.” Dr. Lilian Calderón-garcidueñas Romieu and her colleagues also
For as long as we have polluted showed in a series of studies that the
our air, people have felt effects on their city’s pollution worsens asthma in
health. But identifying and quantify- of tropospheric ozone formed in smog children, particularly those with certain
ing those impacts poses a challenge (not nitrogen oxides, as was expected). genetic profiles. In 2008 her team
for scientists. For researchers want- City officials responded by targeting analyzed data from 200 asthmatic and
ing to understand pollution’s health VOC emissions for reduction. healthy children and found that children
impacts—and design solutions for Few people today understand in areas with more traffic and pollutants
people like Guadalupe—what better Mexico City’s air pollution in more coughed, wheezed, and used medica-
place to go than Mexico City, long detail than Armando Retama, the city’s tion more often.
home to some of the world’s worst air director of atmospheric monitoring. But Another Mexican researcher, Lilian
pollution? he may grasp its impacts best when Calderón-Garcidueñas, has led several
A key first step is to deter- he leaves town. “I can breathe better. studies comparing chest X-ray films
mine what’s actually in the air. One I’m not all dry. My eyes aren’t irritated. and medical records of Mexico City
researcher who has led the way is My skin doesn’t crack,” he says. “We children with those of similar children
Mario Molina, the Nobel Prize–winning have chronic symptoms that we aren’t from nonpolluted locations. Her team
chemist who helped discover the aware of.” found hyperinflation and other problems
cause of stratospheric ozone deple- Most health impacts of urban with the lungs of the Mexico City youth.
tion and who appears in this chapter’s pollution affect the respiratory system. Mexico City children also reported
other Science behind the Story At high altitudes like Mexico City’s, many respiratory problems whereas
feature (pp. 488–489). Molina stepped the “thin air” forces people to breathe rural children did not (Figure 1).
away from scholarly work at U.S. deeply to obtain enough oxygen. Air pollution harms the heart
universities to return to his hometown This means they pull more air pollut- and the cardiovascular system, too.
of Mexico City and help address its ants into their lungs than people at Multiple recent studies reveal that
pollution issues. Here, in 2003 and lower elevations. As result, respiratory pollution can affect heart rate, blood
2006, Molina organized intensive air- problems are commonplace. Many pressure, blood clotting, blood vessels,
sampling projects involving hundreds studies have confirmed that Mexico and atherosclerosis. Epidemiological
of scientists. City residents show reduced lung studies (pp. 393–394) show that pol-
Nearly 200 research publications function in comparison with people lution correlates with emergency room
later, these efforts have clarified many from less-polluted areas and that res- admissions for heart attacks, chest
aspects of the city’s pollution. For piratory problems become worse and pain, and heart failure, as well as death
instance, one study used machines emergency room visits become more from heart-related causes.
that could identify and record individual numerous when pollution is severe. Part of the reason smog impacts
particles in real time, and found that Most studies have looked at the cardiovascular system is that
metal-rich particulates from trash incin- short-term exposure, but in 2007 a tiny particulates can work their way
erators were peaking in the morning, research team led by Isabelle Romieu into the bloodstream, causing the
whereas smoke from fires outside the of Mexico’s National Institute of Public heart to reduce blood flow or go out
city blew in during the afternoon. Other Health examined the effects of growing of rhythm. Even young people are
researchers discovered that volatile up amid polluted air. Her team meas- at risk. One Mexican research team
organic compounds control the amount ured lung function in 3170 8-year-old analyzed the hearts of 21 people from

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