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Studying human exposure to air pollution in the lab


Dr. John Balmes, Professor, UC San Francisco/UC Berkeley:     We're going to be faced with sort of a double whammy of air pollution being high in California to start with, and then climate change is going to make it worse. 

With climate change, two of the air pollutants are going to go up, ozone and particulate matter. Particulate matter is soot. The ozone is going to go up because of the direct effects of the increase temperatures that we are going to have in California, especially in the summer months. The more sun the more hot days, the more ozone.  

So, ozone is going to go up with all the climate change models. Particulate matter is going to increase because of increase energy consumption during really hot days, as we need to air condition our homes, schools, and buildings.

At UCSF I do what are called controlled human exposure studies, where we actually have a chamber, the human exposure chamber, where we expose people to pollutants under controlled conditions. In the real world there's always a mixture of pollutants. Ozone, particulate matter, oxides of nitrogen, so it's hard to pinpoint in the real world how much of an effect is due to one versus the other.

In the laboratory, we can expose people only to ozone, and compare that to exposure of clean air.  And so we've done a number of studies with adults with asthma, exposing them to ozone, exposing them to different kinds of particulate matter, exposing them to oxides of nitrogen, and sometimes exposing them to the combination of ozone and an allergen.  

Like I said, with climate change we're going to have increases with both ozone and allergens.  And it turns out that ozone, in advance of exposure to allergens, makes the asthmatic airway more sensitive to the allergen.

We've studied that in the laboratory and shown that ozone enhances the effects of allergen in causing asthma exacerbations. I hope that the message that there are public health impacts of climate change will help galvanize public support around efforts to control green house gas emissions and control climate change.