Q: My husband and I bought a vent free set of gas logs at the end of 1999. My husband this year has been experiencing chronic nosebleeds and
had to go to the doctor and have his nose cauterized. Now I am having nosebleeds. My question is can unvented gas logs cause nosebleeds and if so
are we not using them properly. I called the company who installed them and they said they never heard of gas logs causing nosebleeds.
I spent a couple of hours on the internet and couldn't find any studies linking gas exhaust specifically to nosebleeds , but did come up
with plenty of evidence that at least one of its components attacks the respiratory system.
Among the products of natural gas combustion that enter your breathing space whenever you're operating your vent-free heater is nitrogen dioxide,
or NO2. When NO2 emissions combine with water in the atmosphere, nitric acid is formed. On a global scale, the result is acid rain, which has been
shown to damage plant life and even erode structures made of solid stone. Here's what the Air Quality Ontario website has to say about nitrogen
dioxide and acid rain: "NO2 can irritate the lungs and lower resistance to respiratory infection. Sensitivity increases for people with asthma and
bronchitis. NO2 chemically transforms into nitric acid and, when deposited, contributes to lake acidification. Nitric acid can also corrode metals,
fade fabrics, degrade rubber, and cause substantial damage to trees and crops."
REF: Ontario Ministry of the Environment Website
In an effort to combat acid rain, the U.S. Environmental Protection Agency has set strict NO2 exposure levels for outdoor air. At this writing,
however, the EPA has yet to formulate an indoor air quality standard. The guidelines used by vent free fireplace manufacturers to establish
allowable short-term NO2 exposure levels in the home are ten times higher than the EPA outdoor air standard.
Armed with this information, we went back to the search engines to ask what would happen should nitrogen dioxide come into contact with the moist
interior of a human nose.
Here's a passage from the American Lung Association website that specifically mentions the effect of nitrogen dioxide on human tissues: "Nitrogen
dioxide is an odorless, colorless gas that is produced when fuel is burned. NO2 irritates the mucous membranes in the eye, nose and throat..."
REF: American Lung Association Website
Here's another, from the US Occupational Safety & Health Administration (OSHA) site: Nitrogen dioxide is classified as a respiratory irritant and
the route of exposure is mainly inhalation. Symptoms of chronic exposure include headache, weakness, loss of appetite, nausea, sores in nose and
mouth, erosion of teeth; emphysema.
REF: OSHA Website
The above references indicate that nitrogen dioxide exposure irritates "wet" human tissues like the eyes, nose and throat. This would seem to
suggest that there is at least grounds for suspicion as to a tie-in between the exhaust from your vent free gas logs and the nosebleeds you and your
husband are experiencing.
how much CO2 a vent-free
fireplace exhausts into the breathing space
a recent study of the effects of
long-term exposure to CO gases
Read a posting about vent-free gas appliances
from an indoor air quality scientist
what Consumer Reports Magazine has to say about vent-free products
Read letters in defense of vent-free products
Read our opinion about vent-free gas
a 2016 ASHRAE standard that
could eliminate the entire vent-free product category in the US
Have a vent-free experience you'd like to report? Here's a link
to the Consumer Product Safety Commission
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