Featured Research

from universities, journals, and other organizations

With you in the room, bacteria counts spike -- by about 37 million bacteria per hour

Date:
March 28, 2012
Source:
Yale University
Summary:
A person's mere presence in a room can add 37 million bacteria to the air every hour -- material largely left behind by previous occupants and stirred up from the floor -- according to new research.

Rendering of bacteria. A person's mere presence in a room can add 37 million bacteria to the air every hour -- material largely left behind by previous occupants and stirred up from the floor -- according to new research by Yale University engineers.
Credit: Jezper / Fotolia

A person's mere presence in a room can add 37 million bacteria to the air every hour -- material largely left behind by previous occupants and stirred up from the floor -- according to new research by Yale University engineers.

"We live in this microbial soup, and a big ingredient is our own microorganisms," said Jordan Peccia, associate professor of environmental engineering at Yale and the principal investigator of a study recently published online in the journal Indoor Air. "Mostly people are re-suspending what's been deposited before. The floor dust turns out to be the major source of the bacteria that we breathe."

Many previous studies have surveyed the variety of germs present in everyday spaces. But this is the first study that quantifies how much a lone human presence affects the level of indoor biological aerosols.

Peccia and his research team measured and analyzed biological particles in a single, ground-floor university classroom over a period of eight days -- four days when the room was periodically occupied, and four days when the room was continuously vacant. At all times the windows and doors were kept closed. The HVAC system was operated at normal levels. Researchers sorted the particles by size.

Overall, they found that "human occupancy was associated with substantially increased airborne concentrations" of bacteria and fungi of various sizes. Occupancy resulted in especially large spikes for larger-sized fungal particles and medium-sized bacterial particles. The size of bacteria- and fungi-bearing particles is important, because size affects the degree to which they are likely to be filtered from the air or linger and recirculate, the researchers note.

"Size is the master variable," Peccia said.

Researchers found that about 18 percent of all bacterial emissions in the room -- including both fresh and previously deposited bacteria -- came from humans, as opposed to plants and other sources. Of the 15 most abundant varieties of bacteria identified in the room studied, four are directly associated with humans, including the most abundant, Propionibacterineae, common on human skin.

Peccia said carpeted rooms appear to retain especially high amounts of microorganisms, but noted that this does not necessarily mean rugs and carpets should be removed. Extremely few of the microorganisms commonly found indoors -- less than 0.1 percent -- are infectious, he said.

Still, understanding the content and dynamics of indoor biological aerosols is helpful for devising new ways of improving air quality when necessary, he said.

"All those infectious diseases we get, we get indoors," he said, adding that Americans spend more than 90 percent of their time inside.

The researchers have begun a series of similar studies outside the United States.

The paper's lead author is J. Qian of Yale. Other contributors are D. Hospodsky and N. Yamamoto, both of Yale, and W.W. Nazaroff of the University of California-Berkeley.

The research was supported by the Alfred P. Sloan Foundation.


Story Source:

The above story is based on materials provided by Yale University. The original article was written by Eric Gershon. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. Qian, D. Hospodsky, N. Yamamoto, W. W. Nazaroff, J. Peccia. Size-resolved emission rates of airborne bacteria and fungi in an occupied classroom. Indoor Air, 2012; DOI: 10.1111/j.1600-0668.2012.00769.x

Cite This Page:

Yale University. "With you in the room, bacteria counts spike -- by about 37 million bacteria per hour." ScienceDaily. ScienceDaily, 28 March 2012. <www.sciencedaily.com/releases/2012/03/120328172255.htm>.
Yale University. (2012, March 28). With you in the room, bacteria counts spike -- by about 37 million bacteria per hour. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/2012/03/120328172255.htm
Yale University. "With you in the room, bacteria counts spike -- by about 37 million bacteria per hour." ScienceDaily. www.sciencedaily.com/releases/2012/03/120328172255.htm (accessed August 1, 2014).

Share This




More Plants & Animals News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins