Drive down just about any main street in Anytown, USA, and you will notice those unsightly dark streaks running down the roofs and siding of houses. You also might notice that those streaks are more than just dark-colored but often include a vast array of greens, browns, yellows, and the like. They extend beyond the roof to encompass the northerly sides of buildings and cling to gutters and window frames. It’s so widespread you could call it an epidemic. If you are experiencing respiratory problems, this seemingly insignificant microorganism could be to blame.
Primary Colonizer Science
Microorganisms (such as bacteria) are often the primary colonizers of newly created environments. They colonize what initially appear to be inhospitable substrates such as bare rock, glacier surfaces, and even the exterior of the International Space Station.
The next microorganism to arrive are the Lichens, organisms formed from a symbiotic relationship between fungi and algae. Well, our roofs and building exteriors could be called inhospitable substrates, and these extremophile bacteria are colonizing them at alarming rates.
Asphalt Shingles
Asphalt shingles are a type of roof shingle that uses asphalt for waterproofing purposes. An American invention first used in 1903, asphalt shingles have been used in roofing projects all over the globe for over a century. It is relatively inexpensive, easy to install, and available in many colors. Making asphalt shingles the go-to roofing material for many homes.
Unfortunately, changes in the asphalt mix are attracting primary colonizing bacteria, the most prevalent being Gloeocapsa magma, which gained notoriety in the Southeast in the 1990s for the dark stained roofs it causes. C. magma has since spread throughout the United States and Canada. It’s probably in your neighborhood, and you didn’t even give it a second thought. But if your family is having odd respiratory issues, you might want to pay closer attention to this cyanobacteria.
What is Gloeocapsa Magma?
It is a cyanobacteria that originates in fresh water and relies on photosynthesis for energy. As the bacteria drifts from local water sources and starts to colonize your roof, it initially looks like algae in part due to its greenish-blue color.
It can thrive anywhere on your asphalt shingle roof, but it tends to favor north-facing sides of your home that hold moisture a little longer. But it isn’t the only airborne algae or cyanobacteria found. There are dozens and dozens of these microorganisms that have been shown to induce allergens or produce toxins (Genitsaris, 2011).
Is It Dangerous?
Gloeocapsa magma is a particularly aggressive fungus that can wreak havoc with your roof as it eats away at the calcium carbonate (CaCO3) in the limestone filler used to weigh your asphalt roof shingles down. It also can join with fungus to create Lichens, tougher organisms than algae alone. All combined, they will be unsightly, reduce the value of your home, and shorten the life expectancy of the roof,
And while C. magma eats your roof; it will cause the shingles to weaken and start to break down into small dust-like granules. Most experts within the subject area conclude the bacteria to be harmful if left untreated, as the growth holds moisture within shingles, causing premature aging, rotting, and/or granule loss.
As the bacteria goes through its life cycle it too will die and start to breakdown casting off secondary metabolites like Cyanotoxins. When on your home, Cyanotoxins saturate the resulting roof dust much the same way it collects along the shorelines of lakes, ponds and rivers. There it can work its way into the bio-burden of the home or impact occupants entering and exiting the home.
Health Effects from Cyanotoxin Exposure
While the research regarding C. magma on your roof is scant, exposure to cyanotoxins has been well-established around algal blooms and red tide. Adverse health effects may range from a mild skin rash to serious illness or, in rare circumstances, death. Acute illnesses caused by short-term exposure to cyanobacteria and cyanotoxins during recreational activities include hay fever-like symptoms, skin rashes, and respiratory and gastrointestinal distress. And yes, your dog is susceptible too.
What Do I Do Now?
There currently is no cure to eradicate roof algae, only better management where roof replacement is the best choice. While the research on the topic regarding the dangers of rooftop fungus, algae, and lichens is scant, experts do agree that fungus should be remediated and water-borne cyanobacteria should be avoided. It’s best to play it safe and get rid of it if you have it. Or reach out to the Indoor Air Quality (IAQ) experts at GreenWorks if you suspect your IAQ has been compromised.
References
Asphalt Roofing Manufacturers Association (ARMA). (2017, 05 10). History of Alphalt Roofing and Algae Discoloration of Roofs. Retrieved from Asphalt Roofing: https://www.asphaltroofing.org/algae-discoloration-of-roofs/
Environmental Protection Agency. (2023, 07 13). Health Effects from Cyanotoxins. Retrieved from Cyanobacterial HABs: https://www.epa.gov/cyanohabs/health-effects-cyanotoxins
Environmental Protection Agency. (2023, 07 11). Learn about Cyanobacteria and Cyanotoxins. Retrieved from Cyanobacterial HABs: https://www.epa.gov/cyanohabs/learn-about-cyanobacteria-and-cyanotoxins
European Space Agency. (2005, 08 11). Lichen Survives in Space. Retrieved from European Space Agency Science & Exploration: https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Lichen_survives_in_spaceGenitsaris, S. (2011). Airborne Algae and Cyanobacteria: Occurance and Related Health Effects. Frontiers in Bioscience, 772 – 787.
