Bugs, Pollen, Heat: Summer Extending Beyond Labor Day? (Op-Ed)

crops, farming, wheat — (Image credit: vovan | Shutterstock)

Kim Knowlton is a senior scientist on the Natural Resource Defense Council (NRDC)'s Global Warming and Health Project. This Op-Ed is adapted from a post that appeared on the NRDC blog Switchboard. Knowlton contributed this article to Live Science's Expert Voices: Op-Ed & Insights.

Labor Day may mark the traditional end of summer, but summer isn't quite over yet. Many of us can look forward to enjoying more days outdoors with friends and family.

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Students heading back to school are getting sent back home, as searing temperatures in Midwestern states, coupled with schools that lack air conditioning, put kids' health at risk. Ninety people at the Minnesota State Fair were treated for heat-related illnesses this year. This past July, many states saw highways buckle in the extreme heat, and that same month, the U.S. Environmental Protection Agency (EPA) warned that the hot temperatures were making air pollution worse in New England. In Indianapolis this summer, firefighters had to evacuate the 300 residents of a senior home to protect their health from the heat.

We're all susceptible to extreme heat. It's especially hard on people with kidney stones, or with migraine headaches, and makes ground-level ozone air pollution — the main component of smog — measurably worse. But remember, the heat- and air-pollution is hardest on the most vulnerable people: those age 65 and older, young children, people with heart or lung illnesses and economically disadvantaged households.

We shouldn't assume everyone can stay cool these days either: many Americans don't have home air conditioning, or can't afford to run it. A U.S. Centers for Disease Control and Prevention (CDC) study of heat-related deaths during a 2012 U.S. heat wave estimated that 16 percent of those who died had an air conditioner, but it wasn't turned on. And 63 percent didn't have any air conditioning at all. Half of the heat fatalities were people aged 65 and older.

Eight cases of dengue fever were recently reported in southeastern Florida, and dengue hospitalizations in the U.S. have tripled from 2000 to 2007. Be grateful if you've never heard of dengue; this painful viral illness is known to many international travelers. It can be passed from person to person by infected mosquitoes. Dengue infections hit an estimated 100 million people worldwide, mostly in the tropics and subtropics, each year. Symptoms include high fever, rash and terrible joint and muscle pains; some 22,000 people die. Those eight Florida cases this year may not sound like a lot, but they were likely transmitted locally, which means carried by infected Florida mosquitoes that bit their unfortunate human victims. There were 28 locally acquired dengue cases in Florida in 2009 and 2010; hundreds of locally transmitted cases in Texas and Hawaii in recent years; and 2010 saw the largest outbreak in Puerto Rico's history.

Author Linda Marsa has just penned a terrific new book, "Fevered" (Rodale; 2013), which details how dengue fever has reached into North America and how a warming climate has a hand in the spread of the mosquito that can carry it. This book describes climate-health effects through the eyes of the people affected and interviews researchers who are looking closely at those connections, offering stories about ways that communities are getting climate-prepared and designing plans to thrive. I've had a chance to talk with Linda about dengue fever and her new book is a great resource.

Ragweed pollen production is in full swing now across much of the U.S., and warmer temperatures mean longer seasons for those pesky plants to pump pollen into the air. One study in a swath of midwestern North Americas found that ragweed pollen season has lengthened by up to 27 days in just the last 15 years. But with summer heat still upon us, ozone smog is also peaking in many parts of the nation: the double whammy.

Let's connect the dots here: All three of these summertime companions — heat, bugs, and plants — are being affected, right here and right now, by climate change . Heat waves far too often aren't mere inconveniences — they kill people. And climate change fuels longer, hotter and more frequent heat waves. Rainfall and temperature patterns are changing in ways that are allowing the dengue fever vectors — mosquitoes that can transmit this painful viral illness — move into new areas of the United States. And carbon dioxide, the No. 1 form of carbon pollution we produce, actually makes ragweed plants grow lusher and produce more pollen. And warming weather lets ragweed plants pump their pollen into the air (and find its way into your airways) for days or weeks longer.

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