News

Climate Change: Good for Weeds, Bad for Allergies

An allergy sufferer sneezes, and scientists say rising average temperatures and elevated levels of carbon dioxide are spurring the growth of many weedy, allergenic plants, and extending the season of suffering for pollen-sensitive people across the countr
An allergy sufferer sneezes, and scientists say rising average temperatures and elevated levels of carbon dioxide are spurring the growth of many weedy, allergenic plants, and extending the season of suffering for pollen-sensitive people across the countr

Multimedia

Zulima Palacio

More than 50 million people in the United States suffer from allergies, and their numbers are growing. New studies suggest that climate change may be at least partly to blame. Scientists say rising average temperatures and elevated levels of carbon dioxide are spurring the growth of many weedy, allergenic plants - such as ragweed - and extending the season of suffering for pollen-sensitive people across the country.

At the U.S. Department of Agriculture's research center near Washington, D.C., plant physiologist Lewis Ziska said weeds - defined as any unwanted plant - appear to be thriving in today's atmosphere, which is richer in carbon dioxide, or CO2. And Ziska said agricultural research studies show that if climate trends continue, allergy sufferers will have to endure longer and more intense pollen seasons in the decades ahead.

"The average ragweed plant growing in the year 1900, for that CO2 concentration was producing about 5 grams of pollen," he said. "If you go forward in time to the 1990s and look at the CO2 concentration at that time, the average ragweed produced about 10 grams of pollen. If you go into the future 50 years from now, at the [expected] CO2 concentration, that ragweed will produce 20 grams of pollen."

Ziska began studying allergenic weeds and pollen 10 years ago. He said the more pollen a weed puts out, the more potential harm there is to public health and to agriculture, where weeds can steal water, soil nutrients and light from commercial crops. Ziska said one of the most common and most allergenic weeds is the fast-growing plant called ragweed.

“This is common ragweed coming up in the spring," he said. "It can get up anywhere from four to six feet (1.5 to 2 meters) tall.”

Dr. Darryl Zeldin is a senior investigator and acting clinical director at the National Institute for Environmental Health Science in North Carolina. He said common allergies have been on the rise for the past 10 to 15 years. And he said that if there's going to be more pollen from weeds in the years ahead, he's certain the number of allergy sufferers - now estimated at 50 million people - will continue to rise, as well.

Zeldin said asthma and allergies are closely related. Most people with asthma also suffer from allergies.

“Allergies are thought to cost the public somewhere in excess of $8 billion to $10 billion every year, in both direct and indirect costs," said Zeldin. "Asthma is also a major issue and costs billions of dollars a year, not just in doctor's office visits, in hospitalizations, and emergency department visits.”

Zeldin also said there are many causes for allergies, and people with allergies often are sensitive to more than one weed. His latest research on the subject has shown that environmental and genetic factors play a role as well. And there is evidence of a connection between a pre-disposition to asthma and allergies, and obesity and cardiovascular disease.

“Asthma and allergies are a major health problem in the U.S.," he said. "(They) cost a lot of money, major cost of symptoms and hospitalizations and doctor’s office visits and there are not real cures.”  

Among the thousands of known weed species, only eight or 10 are known to induce allergies. Many species of weeds, however, have become resistant to herbicides. And that means more money will be needed for health and agricultural research, including new and safer methods of controlling weeds.

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Nobel Prize Winner Malala Talks to VOAi
X
August 31, 2015 2:17 AM
Nobel Peace Prize winner Malala Yousafzai met with VOA's Deewa service in Washington Sunday to talk about women’s rights and unveil a trailer for her new documentary. VOA's Katherine Gypson has more.
Video

Video Nobel Prize Winner Malala Talks to VOA

Nobel Peace Prize winner Malala Yousafzai met with VOA's Deewa service in Washington Sunday to talk about women’s rights and unveil a trailer for her new documentary. VOA's Katherine Gypson has more.
Video

Video War, Drought Threaten Iraq's Marshlands

Iraq's southern wetlands are in crisis. These areas are the spawning ground for Gulf fisheries, a resting place for migrating wildfowl, and source of livelihood for fishermen and herders. Faith Lapidus has more.
Video

Video Colombians Flee Venezuela as Border Crisis Escalates

Hundreds of Colombians have fled Venezuela since last week, amid an escalating border crisis between the two countries. Last week, Venezuelan President Nicolas Maduro ordered the closure of a key border crossing after smugglers injured three Venezuelan soldiers and a civilian. The president also ordered the deportation of Colombians who are in Venezuela illegally. Zlatica Hoke reports.
Video

Video Rebuilding New Orleans' Music Scene

Ten years after Hurricane Katrina inundated New Orleans, threatening to wash away its vibrant musical heritage along with its neighborhoods, the beat goes on. As Bronwyn Benito and Faith Lapidus report, a Musicians' Village is preserving the city's unique sound.
Video

Video In Russia, Auto Industry in Tailspin

Industry insiders say country relies too heavily on imports as inflation cuts too many consumers out of the market. Daniel Schearf has more from Moscow.
Video

Video Scientist Calls Use of Fetal Tissue in Medical Research Essential

An anti-abortion group responsible for secret recordings of workers at a women's health care organization claims the workers shown are offering baby parts for sale, a charge the organization strongly denies. While the selling of fetal tissue is against the law in the United States, abortion and the use of donated fetal tissue for medical research are both legal. VOA’s Julie Taboh reports.
Video

Video Next to Iran, Climate at Forefront of Obama Agenda

President Barack Obama this week announced new initiatives aimed at making it easier for Americans to access renewable energy sources such as solar and wind. Obama is not slowing down when it comes to pushing through climate change measures, an issue he says is the greatest threat to the country’s national security. VOA correspondent Aru Pande has more from the White House.
Video

Video Arctic Draws International Competition for Oil

A new geopolitical “Great Game” is underway in earth’s northernmost region, the Arctic, where Russia has claimed a large area for resource development and President Barack Obama recently approved Shell Oil Company’s test-drilling project in an area under U.S. control. Greg Flakus reports.
Video

Video Philippine Maritime Police: Chinese Fishermen a Threat to Country’s Security

China and the Philippines both claim maritime rights in the South China Sea.  That includes the right to fish in those waters. Jason Strother reports on how the Philippines is catching Chinese nationals it says are illegal poachers. He has the story from Palawan province.
Video

Video China's Spratly Island Building Said to Light Up the Night 'Like A City'

Southeast Asian countries claim China has illegally seized territory in the Spratly islands. It is especially a concern for a Philippine mayor who says Beijing is occupying parts of his municipality. Jason Strother reports from the capital of Palawan province, Puerto Princesa.
Video

Video Ages-old Ice Reveals Secrets of Climate Change

Ice caps don't just exist at the world's poles. There are also tropical ice caps, and the largest sits atop the Peruvian Andes - but it is melting, quickly, and may be gone within the next 20 years. George Putic reports scientists are now rushing to take samples to get at the valuable information about climate change locked in the ice.

VOA Blogs