Narrator: This is Science Today. Since the late 1980s, rates of asthma - especially in children - have been greatly rising. Kathleen Mortimer, an epidemiologist at the University of California, Berkeley has recently found children born prematurely or of low birth weight, are the most susceptible to smog-induced asthma.
Mortimer: This was the first study that identified that as a susceptible subgroup as far as I know. I mean, there's been lots of evidence that in general, children of low birth weight have more respiratory problems throughout life and it lasts even until adulthood. But this was the first one that looked particularly at air pollution.
Narrator: This study may have major public health implications because this higher susceptibility doesn't just affect asthmatic children….
Mortimer: It may be that in the general population, children who were born low birth weight or premature also show this greater response and that has a bigger public health impact because in general, only less than ten percent of the population has asthma. But if worldwide or nationwide, children even without asthma are greater responders if they're premature, then it hits a bigger population.
Narrator: For Science Today, I'm Larissa Branin.