When my son was younger, I always wondered if I was affecting his health by using a stroller. This had nothing to do with how green the carriage’s manufacturing process was, but everything to do with his stroller-bound proximity to vehicular exhaust systems. As I watched other parents using more lofty modes of transport (back carriers, front carriers and slings), I wondered if their children were less at risk of directly inhaling automotive pollutants than my son, whom I was shuttling around closer to the ground. Yet could the few feet of airspace a piggyback affords its passenger drastically reduce exposure to the breathable pollution belched by passing or idling vehicles?

“Literature suggests that pollutant levels drop off rapidly with elevation,” says Dr. John Durant. Dr. Durant is a Professor in the Civil & Environmental Engineering department at Tufts University and author of various papers on the subject – including the one that drew me to his work, ‘Near-highway pollutants in motor vehicle exhaust: A review of epidemiologic evidence of cardiac and pulmonary health risks’. His studies have proven that in metropolitan environments children and adults are more susceptible to the maladies associated with vehicular exhaust than their exurban, suburban and rural friends. On city streets the risk is compounded by the daily dance urban planners have citizens engage in, hot stepping in and out and alongside traffic.

I contacted Dr. Durant and posed my question to him. He was compelled by the hypothesis and though he noted that there are no studies done that would confirm or deny my claim, he was willing to make a very educated guess. “I think the length scale of measurement has been on the scale of several meters at a time and not the submeter scale that would be necessary to show that stroller-level exposure is higher than shoulder-level exposure,” he explained.

“With all of the turbulence and mixing that occurs in the near roadway environment, I would be surprised if there were a measurable difference between stroller-level and shoulder-level exposures – unless they were right up next to passing cars,” continued Dr. Durant. “But if they are walking on sidewalks and a few meters away from the traffic, then I don’t expect that the difference would be significant.”

In other words, contrary to what layman commonsense might dictate, whether in a stroller or on your shoulders, if your child is within a few meters of traffic, he or she will be exposed to harmful vehicular pollutants such as ultrafine particulates (UFP), black carbon (BC), oxides of nitrogen (NOx), and carbon monoxide (CO). So unless you plan on creating some Seussian creation that hoists your child to a considerable elevation, the air is no cleaner up there than it is down here.

And that’s not good news. In his study Dr. Durant found an “elevated risk for development of asthma and reduced lung function in children who live near major highways.” In a separate study that links vehicular exhaust to lung cancer, the authors “single out diesel exhaust as a major contributor to the increased lung cancer risk.”

HERE ARE FIVE WAYS TO COMBAT AUTOMOTIVE POLLUTION:

1) Parents can take action by following Dr. Durant’s suggestion: “Have them walk their children as far away from tailpipes as possible.” Utilize the entire 9 feet (2.7 meters) of clearance city sidewalks provide. You can also try sticking to streets and avenues where cars are restricted to one lane of traffic, and from which diesel-consuming trucks are usually banned.

2) It might be a bit much to check the traffic report before heading out for a walk, but it doesn’t hurt to be aware of excess automotive congestion along your route and making a tree-lined detour.

3) There are various child-sized face masks available on the market that screen out hazardous particles. This is not a very practical (or fashionable) option. You may end up looking ‘Michael Jackson crazy’, but you’ll be sure your little one is protected.

4) If you are that rare city dweller whom actually owns an automobile, be sure to have your vehicle’s exhaust system checked at regular intervals. It’s also a good idea to find out the type of fuel that runs your kid’s school bus and advocate for greener options such as less idling.

5) It is also possible that some days are worse than others. Smog is a combination of vehicular and industrial emissions. Its intensity varies and exists in most major cities. Smog can be tracked using the Air Quality Index at AIRNow.