Re: Re:Does using humidifers in the winter spread mold, bacteria?

[Guest guest]

Hi Jeff,

I am going to save this because I am suppose to be

sleeping by a humidifier but due to the mold content

in this house, I can't. However, we are moving into a

new house. It has carpet in the bedrooms, which is

new carpet. I want to cover them and was told you know

of a cover. I have search the net and stores for such

a cover and no luck. Where can I buy this carpet

cover? I will really appreciate it if you can send me

this info.

Also, I read your book last year, it was really good.

TIA,

Jackie

--- Jeff May <jeff@...> wrote:

> Sue,

>

> The doc quoted in the article said there is " no

> evidence that he knows of

> that humidifying air reduces colds " but there are

> papers that show that

> comfortable levels of RH can reduce respiratory and

> other symptoms:

>

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[Guest guest]

What about putting a small amount of vinegar in the the water to help keeping it

from fungi? Just a thought.

Jeff May <jeff@...> wrote: Sue,

The doc quoted in the article said there is " no evidence that he knows of

that humidifying air reduces colds " but there are papers that show that

comfortable levels of RH can reduce respiratory and other symptoms:

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1474709

" Indirect health effects of relative humidity in indoor environments "

" A review of the health effects of relative humidity in indoor environments

suggests that relative humidity can affect the incidence of respiratory

infections and allergies. Experimental studies on airborne-transmitted

infectious bacteria and viruses have shown that the survival or infectivity

of these organisms is minimized by exposure to relative humidities between

40 and 70%. Nine epidemiological studies examined the relationship between

the number of respiratory infections or absenteeism and the relative

humidity of the office, residence, or school. The incidence of absenteeism

or respiratory infections was found to be lower among people working or

living in environments with mid-range versus low or high relative

humidities. The indoor size of allergenic mite and fungal populations is

directly dependent upon the relative humidity. Mite populations are

minimized when the relative humidity is below 50% and reach a maximum size

at 80% relative humidity. Most species of fungi cannot grow unless the

relative humidity exceeds 60%. Relative humidity also affects the rate of

offgassing of formaldehyde from indoor building materials, the rate of

formation of acids and salts from sulfur and nitrogen dioxide, and the rate

of formation of ozone. The influence of relative humidity on the abundance

of allergens, pathogens, and noxious chemicals suggests that indoor relative

humidity levels should be considered as a factor of indoor air quality. The

majority of adverse health effects caused by relative humidity would be

minimized by maintaining indoor levels between 40 and 60%. This would

require humidification during winter in areas with cold winter climates.

Humidification should preferably use evaporative or steam humidifiers, as

cool mist humidifiers can disseminate aerosols contaminated with allergens. "

IMPORTANT NOTE: The authors are INCORRECT about evaporative humidifiers as

portable units are generally NOT safe to use. I have investigated many and

ALL contained microbiological growth (bacteria and often significant mold

colonization).

The most imoprtant thing to keep in mind is that you MUST monitor the RH

with a hygrometer. If it gets much over 40% in winter, condensation and

other problems may occur. Then the RH has to be lowered.

Also keep in mind that the maximum safe indoor RH is also affected by the

outdoor temperature. When it is extremely cold out, the maximum safe indoor

RH may be 30% or less; otherwise there will be excessive condensation.

One reason I chose 35% for the article is because most inexpensive

hygrometers are off by +/- 5%. But 40% RH is OK so long as there is not

excessive condensation. (Measure the RH in a cold, exterior corner at the

floor/wall intersection and if the RH is over 75%, you may develop a mold

problem.)

Warm-mist humidifiers (except for the scalding issue) are the ONLY safe type

of humidifier to use. These mix room air with the steam.

Also, do not use a portable humidifier unless it has a humidistat (e.g.

Honeywell QuickSteam). Do not use old-fashioned steam humidifiers that just

boil water without any controls.

C. May, M.A., CIAQP

Re: Does using humidifers in the winter spread mold, bacteria?

> Posted by: " ssr3351@... " ssr3351@... ssr3351

> Date: Mon Dec 10, 2007 9:54 am ((PST))

>

>

> Wow! I thought 35% was pretty low and always thought RH should be 50 or

> below. Right now ours seems to be running between 35 to 38 %. Older people

(like

> my mother) always said to run a humidifier in the winter so the furniture

> doesn't dry out but what did they do years ago without them?! Did the house

and

> furniture dry out and fall apart?

>

> Sue

>

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