Thursday, February 22, 2024 Feb 22, 2024
63° F Dallas, TX
Nature & Environment

Don’t Spray Me, Bro, Ctd.

By Tim Rogers |

My wife has been blowing up my cell today. “What do we do about this aerial spraying? I’ve read that we should turn off the AC during the spraying. And what about the kids tomorrow? Should we let them outside? I’m telling you, it’s like Agent Orange. A few years from now, when we’re all about die, I’ll have the last laugh.” I’m not making any of this up.

So, to appease my wife and help you, the dear FrontBurnervian, I asked an expert. No, not the city of Dallas. A real expert. In his rants against the aerial spraying, Jim Schutze has referred to the work of a UT Austin scientist named Andrea Gore. She’s a professor of pharmacology and toxicology. I asked Dr. Gore what she would do if she lived someplace where they were about to spray this poison from planes. Her response:

Thanks for your email. David Crews just happens to be sitting next to me, as not only are we scientific collaborators but we are also married. We discussed your question and we do have some recommendations.

Ideally, all people should avoid contact with pesticides during periods of active spraying by staying indoors.

Some individuals are particularly vulnerable and should take careful measures to stay inside during and immediately after the spraying. These include women who are pregnant or suspect they may be pregnant; infants and children; and anyone planning to conceive a child in the near future, both men and women.

Toys and lawn care items that are sitting outside should be brought inside or covered before the spraying. This will minimize contact with any sprayed matter that settles on them. If you forget, wash toys before allowing children to play with them – everything ends up in a child’s mouth at some point. You can try hosing down playsets and outdoor furniture.

We hope this is helpful and we’re hopeful that we’re upwind from the spraying!

That last line pretty much tells you what you need to know. This spraying stuff is serious. Especially when it comes to people who are pregnant, might be pregnant, or, you know, might have sex. Which is pretty much everyone. But what about the AC? Should we turn it off? I followed up with that specific question. Dr. Gore wrote:

David and I had a discussion on exactly this issue. Because we’re both biologists we’re less confident on giving advice about the A/C. I don’t see a down-side to using the A/C. Of course separate from the issue of spraying, people should be reminded to clean the filters on their A/Cs because when the filters get really dirty they don’t do their job.

You may want to contact someone with expertise on air pollution and particulate matter. Dr. Richard Corsi has a great deal of expertise/credibility here.

I am waiting to hear from Dr. Corsi and will update this post as soon as I do.

UPDATE: Dr. Corsi gives us a wonderfully thorough response. You should read every word. But the short version: most houses will be fine. Leave your AC running. There are exceptions, however:

I have been following this story. Unfortunately, there is no “short” or “perfect” answer to your question and I regret that I will have to use the words “it depends” a few times.  So, I will try to give the best answer that I can give. 
First, there are BIG differences between most homes and other types of buildings, e.g., offices, schools, etc.  In this case, a major difference relates to whether there is a design (part of the construction) mechanical air intake in the building. 
Most homes in the United States  do not have design/mechanical air intakes.  Some newer and more expensive homes do, as well as homes with evaporative coolers [swamp coolers] — there are probably few swamp coolers in Dallas.  This is unlike most office buildings, schools, etc. for which operation of the HVAC system involves taking in outdoor air.  In those types of buildings the HVAC system being on during spraying (or even for a few hours after spraying as the pesticides are dispersed) will lead to transport of pesticides indoors where people spend most of their time.  Note that much of the pesticide is likely to reside on particles and so in these non-residential buildings some of the particles will be collected on HVAC filters, which provide some protection while being indoors.  The degree of protection depends on the quality of the filter and whether it is seated correctly in the system to avoid by-pass around the filter (more common than people think).   HOWEVER, the contaminated filters (once they collect pesticide) will continue to “leach” small amounts of pesticide over time as they partition to the gas-phase, and so it is a good idea to replace the HVAC filters once this spraying episode is over. 
Now to homes.  As stated above, most US homes do not have a design air intake and are designed for 100% recirculation in the HVAC system.  Air that enters homes does so through infiltration (flow under doors, around windows, etc.) and by natural air flows when homeowners open windows, doors, etc.  In theory, if windows and door are closed use of the  HVAC system should not substantially increase outdoor air flow into homes.  HOWEVER, HVAC ducts always leak to some extent and homes with leaky supply ducts lose air to the attic and then out to the environment. This sets up a negative pressure indoors and pulls in more outdoor air through infiltration.  This is the same thing that happens when someone turns on a bathroom exhaust vent or a vent on the hood above their stove.  However, the added outdoor air that comes indoors from operation of the HVAC system is offset to some extent by recirculation through the HVAC filter (more protection with a better filter).  One might actually argue that in homes with well-sealed (or at least not very leaky) ducts and a good HVAC filter there might be some benefit to keeping the HVAC fan on continuously without AC (since systems cycle when AC is used).
So, “it depends”. 
·         If one has a design mechanical air intake they should not use their HVAC fan or AC as there is a direct route for pesticides from outdoor to indoor air.
·         If one has a home without a design air intake (most homes), well-sealed (or not too leaky of ducts) and a good HVAC filter, e.g., at least a MERV 8 and perhaps as high as a MERV 11 filter, there could be some benefit to operating an HVAC fan continuously.
·         If one has a home without a design air intake, typical (relatively leaky) ducts, and a standard HVAC filter, they should probably (if possible given the heat) not use their AC and not use the fan without AC.
Having said that, I think that not using AC leads to a risk of heat stroke for the elderly and ill.  I would consider this a much worse risk than exposure to pesticides (emphatic on this point).  Given the age of my wife and me (in our 50s) and with no children in the home  I might opt to use air conditioning and not worry about the incremental additional exposure to pesticides from AC operation.  I would also be most concerned about my dog, who loves to roll around and occasionally eat grass, and also tracks in chemicals when she comes indoors.  In fact, one recommendation might be for people to try to keep their pets indoors during the spraying.
A possible option is for people to establish an AC set-point that is higher than usual but “tolerable”, assure that all doors and windows are firmly closed.  Flow through large gaps, e.g., at the base of doors, can be reasonably reduced using a slightly damp towel.  If homeowners have access to a portable air cleaner they can use this when they are home and move it around the house to where they or their child is, including the bedroom at night (where we spend the majority of our time when home).  I would personally avoid purchasing air cleaners that emit ozone and opt for one that has a HEPA filter and bed of activated carbon with a minimum clean air delivery rate (CADR) of 150 cubic feet per minute for most rooms.  This is a general rule for most reasonably-sized rooms.  The units are less effective in large rooms.
And importantly, I highly suggest that people avoid the use of any exhaust fans (e.g., in the bathroom or kitchen) that exhaust indoor air outdoors.  When these are on they draw in (from outdoors) an equal amount of air that they push out.
Finally, people will tend to track pesticides in on shoes when they have been outside.  A GREAT way to avoid contaminating indoor surfaces, especially if small children crawl around or play on those surfaces, is to take shoes off before entering the house (like many of our mothers preached to us when we were young). 
I hope that this is helpful in some way.

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