Health Effects of Climate Change

Katie Huston for TEI

When talking about climate change, we often tend to overlook one of its most important and immediate effects, says Christine Rogers: its effect on health.
Rogers, an assistant professor in the department of Public Health, is an aerobiologist, which means she studies airborne biological material. In particular, she’s focusing on how global warming affects allergens, which may have huge implications for people who suffer from allergic diseases.

As the earth heats up, the increase in carbon dioxide has a large fertilization effect on plants, increasing the production of pollen grains. In addition, the temperature increase means the onset of spring is advancing by about one day per year, lengthening the growing season – and the allergy season as well.

“It’s going to cause people who are sensitive to pollen to have symptoms much more frequently, earlier in the season sometimes,” Rogers says.

It’s a subject that hits close to home. Rogers has allergies, and she also contracted asthma at 11 months old, another disease influenced by airborne biological material. When she was six years old, she had an asthma attack that almost killed her.

“It was so bad that I stopped breathing on the way of the hospital,” she says. “So it’s always been an area of interest.”

Although no one knows for sure what causes people to suffer from allergies, approximately 20 percent of the population is affected, and the number of people allergic diseases worldwide, such as asthma, has almost doubled in the last few decades. The causes of the rise are not certain, Rogers says, but it’s changed too quickly to be evolutionary.

“It has to be some combination of environmental factors that is inducing the increase in allergic diseases,” she says.

In research she conducted at the Harvard School of Public Health, where she worked for eight years as a research scientist before coming to UMass in 2006, Rogers showed that ragweed, a common allergenic type of plant, produces more pollen when exposed to higher levels of carbon dioxide.

She compared ragweed grown in current air conditions, about 380 parts per million (ppm) of carbon dioxide, with ragweed grown at 750 ppm. Ragweed grown at the higher level showed a 55 percent increase in the amount of pollen produced. In addition, plants released from dormancy early in the spring, simulating the spring conditions under future climate change, also showed a more than 50 percent increase in pollen production due simply to a longer growing season.

“Even in years when spring is late and would under today’s conditions produce much lower amounts of pollen, there will be high pollen production because of the high CO2. Hence, almost all years are going to be what we consider ‘bad years’ in terms of pollen production and allergen exposure,” Rogers says.
Right now, CO2 in the air is increasing about one ppm per year. Studies have shown, however, that in some cities today the carbon dioxide level is far above average. In the center of Phoenix, Arizona, for example, carbon dioxide has been recorded at 650 ppm.

“These are little microcosms of what the climate might be like 100 years from now,” Rogers says – but for people in cities, global warming may already be affecting allergies.

Most research on the effect of climate change on pollen production has been done with ragweed because it’s easily to manipulate in a greenhouse setup. However, ragweed is not as common in New England as it is in other parts of the country, like the Midwest. So last summer, Rogers, along with Michael Muilenberg, a research fellow in the Department of Public Health, began looking at a different allergen-producing biological species: fungi.

Studying the effect of CO2 exposure on fungi is a challenge. “Many fungi won’t grow in the laboratory, or the way they react in the laboratory may not mimic at all the way they react on normal plant tissue,” says Rogers. “We can’t put them on artificial hosts and do the experiment. We have to provide them with natural hosts.” To do this, Rogers and Muilenberg are growing grass under four carbon dioxide regimes, ranging from 350 to 600 ppm.

In addition, there are two vital questions that need to be answered. First, will more fungi grow on grass exposed to higher carbon dioxide levels? And second, will those spores actually produce more allergens?

Rogers believes there’s a good chance they will. “It’s a reasonable hypothesis to think the fungi will produce more of these proteins, because they are being given the basic building blocks to do so,” she says.
She hopes the project will be finished within the year. If her hypothesis proves true, she says, it will be another piece of ammunition in the fight to convince people of the implications of global warming.

Above all, she is driven by a passion to relate climate change to health. In her courses – this year, she’s teaching Intro to Aerobiology and Indoor Environment and Health – she addresses other connections between global warming and respiratory health, such as the impact of heightened flooding, hurricane activity and precipitation on dampness in indoor spaces.

“Global warming probably is thought by many people to be an energy issue, but when you start talking about it in terms of health, and health of a broad number of people in the general population, then I think it hits home a little more,” Rogers says.

She stresses that the impact of global warming on health, respiratory and otherwise, is something everyone should be concerned about.

“It’s not specialized groups that are in some other part of the world. This would be happening right here in the U.S.,” Rogers says.