There’s something in the air … something more complex

One of the worst forms of pollution by far is air pollution. As we have to keep breathing no matter what the quality of air is, we may end up being exposed to airborne pollutants on a constant basis. Not surprisingly, air pollution has been linked to a wide variety of ailments and illnesses from heart disease to Alzheimer’s disease.

It turns out, however, that air pollution is an even more complex matter than scientists have thought, according to researchers in the U.S. who have just published a study on the matter. Knowing the specific nature and composition of airborne pollutants is key if we are to improve air quality, the researchers say, so they set out to do just that.

They collected air quality samples over three-week periods in the summer in a forest in Michigan, as well as in several parts of Atlanta and New York City. They then carefully analyzed their air samples with a view to observing the molecular makeups of airborne particles that were heavily present in the atmosphere at any one spot. They focused on primary organic aerosols such as those that result from combustion in vehicles (in the form of exhaust) and secondary organic aerosols that result from the oxidation of organic gases and particles in the air.

To their surprise, the researchers say, they found variations in samples taken at the same sites at different times. In most cases, as much as 70% of the compounds at a site were different from each other in consecutive samples, they explain. This means that several factors could be driving the variability in chemical compounds, including weather patterns and local conditions for chemical oxidization.

Albeit these variations are often small, they can make a marked difference cumulatively. “The different types of compounds emitted from cars and plants could vary from car to car or tree to tree,” explains Jenna Ditto, of Yale University. “If you develop an air pollution control policy based on less specific information for organic aerosol, there may be much more variability in the molecular-level composition than you might expect, which could influence aerosol properties and impacts,” she adds.

In other words, air quality control policies should be better finetuned in order for them to have the best effect. “There’s a wealth of information in these details for the field to use,” notes Drew Gentner, an assistant professor of chemical and environmental engineering at Yale. “There’s valuable data that you can capitalize on to understand what’s happening in the whole complex system.”