Vinegar held back one of two common indoor molds on a lab dish, and 70% ethanol held back neither. The EPA says killing mold is not enough anyway, because dead mold can still cause allergic reactions. Find the water, then remove the mold.
If you found a patch of mold and reached for the vinegar or the alcohol spray, a lab test from Australia is worth two minutes. Household-strength vinegar held back only one of two molds common in indoor air, and 70% ethanol held back neither. Even the products that worked on the dish leave the bigger problem in place: dead mold can still cause allergic reactions, and the water that grew it is still there.
None: the effect 70% ethanol had on either mold. Vinegar (4.0% to 4.2% acetic acid) held back Penicillium but did nothing to Aspergillus.
The source
Senthaamarai Rogawansamy, Sharyn Gaskin, Michael Taylor and Dino Pisaniello of the University of Adelaide and Flinders University published the test in the International Journal of Environmental Research and Public Health in 2015. The paper is open access, and the authors declared no conflict of interest.
They took two molds from real air samples, Aspergillus fumigatus (from indoors) and Penicillium chrysogenum (from outdoors), both very common in indoor air. A small drop of each product (20 microliters) went onto a paper disc 9 mm across, which sat on a dish of mold for 7 days. If the mold stayed out of a ring around the disc, the product was holding it back. The authors counted a product as active only if the ring was wider than 9.5 mm. Each test was repeated at least 3 times.
The five products:
- Vinegar, 4.0% to 4.2% acetic acid
- 70% ethanol
- Tea tree oil, as a liquid and as a vapor
- Two hospital and lab disinfectants, one peroxygen-based and one made of alcohol plus a quaternary ammonium compound, tested at several strengths
What they found
- Vinegar: a ring averaging 15 mm against Penicillium. Against Aspergillus, no effect.
- 70% ethanol: no effect on either mold. The authors’ verdict: it “is not suggested as an effective antifungal treatment.”
- Alcohol and quaternary ammonium disinfectant: a 16 mm ring against both molds, but only undiluted. At 75% strength it did nothing.
- Peroxygen disinfectant: worked on both molds only at 10%, which the authors note is ten times the label strength for surfaces. At 5%, 3% and 1% it did nothing to growth.
- Tea tree oil: the best performer on the dish. It stopped Aspergillus completely, with an 83 mm ring, and left a 43.5 mm ring against Penicillium. As a vapor it was weaker against Penicillium (20.6 mm).
Some products slowed spore-making without stopping growth, which the authors count as a partial effect.
One detail stands out. The authors say the Australian mold guideline used by industry there recommends damp wiping with a detergent, vinegar solution or alcohol solution. The two household liquids it names were the two weakest products in this test at their best tested strength. The authors call for checking “common knowledge advice” against evidence.
Why it would work this way
The paper does not test mechanism. Citing earlier work, the authors suggest that vinegar’s acid, alcohol and tea tree oil each damage the mold cell, and that differences in the thickness and makeup of the spore wall may explain why the two molds responded differently to the same product. They also note vinegar does not linger on a surface, which may limit it to hard, non-porous materials.
The limits, stated plainly
This was a dish of agar in a lab. Nobody sprayed a wall, a window frame or a basement joist. The authors say so themselves: products “should also be tested on contaminated surfaces, such as construction materials found within a building.” Two species is a small slice of the molds found in houses, and a 7-day disc test is far from a real cleanup.
The tea tree oil result came with its own warnings. By day 14 its effect on Penicillium had weakened, and spores were forming on every tea tree oil dish. The authors also note its ingredients may sensitize skin and that the effects of breathing its vapor are not well studied. So this paper is no reason to fog a house with essential oil.
What survives: the two DIY liquids most often recommended, vinegar and alcohol, did poorly even in direct contact on a lab dish.
What happens when you fix it
This study tests no house. The authors describe an earlier study in which five antifungal products, bleach and 70% isopropyl alcohol among them, held back mold in pine wood until they were rinsed off, after which the mold came back. That earlier team concluded that most antifungals work on hard surfaces, but spores inside porous materials may be unaffected. (We have not read that earlier study ourselves; this is how these authors summarize it.)
The authors’ own conclusion is that any product has to come with ventilation and lower humidity. The EPA puts it this way (page updated September 8, 2026): some spores will remain, and “these spores will not grow if the moisture problem has been resolved.”
What gets lost in the mold-spray marketing
Natural mold-killer sprays, vinegar hacks and essential oil remedies all sell one idea: kill it and you’re done. The EPA disagrees. Bleach and other biocides are “not recommended as a routine practice during mold cleanup,” and “Dead mold may still cause allergic reactions in some people, so it is not enough to simply kill the mold, it must also be removed.” The EPA also warns never to mix bleach with cleaners that contain ammonia, because toxic fumes can form.
What the data supports
From the EPA’s “Mold Cleanup in Your Home” page (updated June 4, 2026):
- Fix the leak or moisture source first, and dry everything completely.
- Scrub mold off hard surfaces with detergent and water, and dry completely.
- Ceiling tiles, carpet and other porous materials may have to be thrown away if they get moldy.
- Don’t paint or caulk over mold. Clean and dry first.
- Bigger than about 10 square feet (roughly 3 ft by 3 ft), or a lot of water damage? The EPA points to its professional cleanup guide.
Our own advice, not the EPA’s: if a musty smell or a patch keeps coming back after cleaning, treat that as a sign the water source is still there.
Bottom line
In a lab test, vinegar held back one of two common molds and 70% ethanol held back neither. Even a spray that works leaves dead mold behind, and dead mold can still cause allergic reactions. The fix is drying the area and removing the mold. If you can’t find where the moisture is coming from, see how our room-by-room testing works, or book mold testing in Portland or Vancouver.
First step: before you spray anything, find where the water is coming from.
Mold testing in Portland and Vancouver, before the cleanup.
illumenair does mold testing and indoor air quality testing in Portland and Vancouver. We test and report. We do not do remediation.
971-363-5626 · info@illumenair.com · www.illumenair.com
Sources: Rogawansamy S, Gaskin S, Taylor M, Pisaniello D. An Evaluation of Antifungal Agents for the Treatment of Fungal Contamination in Indoor Air Environments. International Journal of Environmental Research and Public Health 2015;12(6):6319-6332. doi:10.3390/ijerph120606319. Read October 30, 2026. U.S. EPA. Should I use bleach to clean up mold? Last updated September 8, 2026; read October 30, 2026. U.S. EPA. Mold Cleanup in Your Home. Last updated June 4, 2026; read October 30, 2026.