Can Vent Free Gas Appliances Cause Nosebleeds?

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.
Thank you.
PJ Jordan

  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.

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Read about how much CO2 a vent-free fireplace exhausts into the breathing space

Read about 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

Read 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 appliances

Read about 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 website.