Asthma is the most frequent chronic noncommunicable disease of childhood in the world¹ and is particularly prevalent in urban settlements, where traffic-related pollution and household dampness—particularly common in slums—can lead to oxidative stress and airway inflammation.² These occur more frequently among children, who are more susceptible to developing asthma because of their narrower airways, their faster breathing rates, and their more frequent breathing through the mouth than adults.² In addition to the growth of urbanization around the world, increasing evidence of the role of early adverse experience^1-3—which is more frequent in contexts of poverty and inequality—in the onset of asthma is a significant reason for concern from a health equity perspective.