Air Sample in Rain

Greetings all!

My company has moved into the Air sampling foray and we are all in the process of taking our training and courses. We are in the Pacific NW and have steady rain from October-March and decent winds of 25mph+ on many days. All the training I have taken says not to sample outdoors in rain, or wait 2 hours after.

How do the rest of you in similar climates function in the fall/winter with regard to mold testing? Often waiting 2 hours still has rain falling and winds blowing, and clients don’t have days to wait in their inspection contingencies for us to come back in most cases, and many times it rains at least a little for 4-5 days in a row.

Thanks in advance for any field insights here.

What did your instructor recommend? I don’t do it but am curious. :slight_smile:

Well all InterNACHI IAC2 trainings all say no rain, or wait at least 2 hours after rain. Another course said light rain is ok. Wind wise, they say face the wind and you will be fine, gusts will happen. I suppose moving closer to the structure would be ok in most cases to take most of the rain out, but the training just doesn’t deviate much from the “no rain” recommendations. Training can be very black/white, but I know there are inspectors here that work in damp, windy conditions most of the year.

Putting the time factor of a real estate contract aside, I cannot perform an outside baseline air sample during or after rains.
The theory is there will be spores unnaturally flying around off trees/shrubs/buildings.
This may affect the spore count, showing higher than normal conditions. They need to settle to the ground first, logical reasoning.
You could get a false determination due to the counts being unnaturally higher outside.
I don’t think there is a way to solve the contract time limits.

Another error I see down here in Florida is inspectors collecting air samples
near the back of the house/near a pool.
The chlorinated vapors can reduce the spore count, again giving a false reading.
Good luck!
<<MG>> State Lic Mold Assessor #MRSA1573 :slight_smile:

We have tried in Missouri in different outdoor climates. Light rain, there is no difference. Heavy rain knocks most spores down. Testing right after a rain has some lower spore counts if it has not rained in days. If it rains about every day, the mold spore counts stay about the same. Snow or ice cover or when below 35 degrees, there is hardly no outside mold spores. I imagine each region of the country might be a little different, especially in costal areas.
I use my van to block any strong winds when testing. Just like testing too close to a supply or return register, a strong wind will blow pass the air trap even if you point it towards the wind.
There are standards set by the ACGHI, if I remember the association right, that gives what are acceptable indoor limits, when an outside sample cannot be taken.
Also keep away from straw and trees whenever possible.