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Question DetailsAsked on 8/6/2016

What could be causing a consistent chlorine or bleach smell in a home we recently purchased?

My wife and I purchased an older home 3 months ago. On the day of the closing we noticed bleach like smell in the house but chalked it up to cleaning supplies or the house being closed up for a period of time.

Three months later the smell persists as strong as ever ---- you can actually smell it outside before you even open up our front door. We've had multiple people under the house investigating the crawl space with no odor. We've had an IAQ expert in our attic and no odor was detected. We've investigated our HVAC units, pool filter system, cleaned the entire house with a light vinegar water solution, aired the house out with commercial fans and the smell will not subside

Next step is to hire an environmental firm to test for what chemical is present in the's strong enough that it will be asborbed into your clothing if you spend 15 minutes in the house.......any thoughts/help are greatly appreciated!

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14 Answers

Voted Best Answer

Sounds dangerous for long exposure or sleeping in, especially if you have children in the house - and almost certain your insurance company will not cover diagnosis, treatment, or temporary living expenses because most specifically exclude chemical exposure losses.

I am going to presume you are pretty sure it is not a decaying body you are smelling, though the odor from even larger varmits like coons and possums generally taper off in about 2-3 months - smaller ones like rates and squirrels and such in the walls or trapped under tubs or such more commonly mummify or dry out completely and stop smelling strongly in a month or less.

Also presuming you can positively say it is not animal xxxx /urine smell from unwanted guests living in your house. That is one source of another opinion at to the source of the smell - an Animal Removal specialist.

Alas - SOOOO many people notice something odd or different in the final inspection but fail to follow up at that time - the reason for the pre-closing final inspection is to be sure there is nothing changed (in a negative way) from the initial viewing and home inspection - if there is, you delay closing until it is resolved to your satisfaction. That would have been the time to open windows and see if it aired out completely, or if not to get a supplemental disclosure from the homeowner on anything they did to cause the smell - cleaning or disinfection or whatever. Unfortunately, while escrow and title companies and lenders routinely delay closings, buyers/sellers are very reluctant to do so - causing problems like this.

I remember one new house where at final inspection the buyers noticed new jagged staggered cracks across the drive that were not there at initial viewing/inspection. They thought oh well, it is a newly paved drive so it will probably crack a few places as it ages, and the Builder agreed in writing to seal cracks for up to 6 months as they occurred - a few days later (soon after closing) the house was several hundred feet down the hillside in the bottom of a ravine, a total loss PLUS had to pay for cleanup and environmental damage because the ravine was part of a wildlife preserve. And of course because it involved land movement their homeowner's insurance provided zero coverage. Result - fo course they were out a house, plus a thirty year mortgage for over a half million $ became immediately due because the house the mortgage was on was destroyed and not covered by insurance - I am sure the couple end up bankrupt because of it.

You could contact your realtor and see if he/she will contact the owner's realtor, may possibly require some sort of hold-harmless agreement to get them to fess up, to get them to disclose anything done that could be causing this - cleaning, new foam insulation, sewer drain or line treatment, etc.

Common causes of this sort of smell - though most would not last months:

0) spillage under kitchen or maybe bathroom cabinet or in laundry area, possible getting in under the bottom board in the cabients - commonly those are loose or lightly nailed down so easy to remove and check underneath. May have spilled a bottle of bleach or such during moveout that smells anuytime it gets moist (like from dishwasher venting of damp air for instance)

1) heavily used or spilled bleach or bleach-based cleanser - airing out would normally clear this out in a couple of days unless in a confined space like in the subfloor under cabinets, or drained out of cabinet under it and from there into or under the flooring

2) bleach used to wash down bathroom, kitchen or basement walls that were growing mildew/mold - unless liberally poured on cracks in the floor or around edges of wall should dissipate in a week or so, but if poured in could be reactivated anytime the area got mosit from humid bathroom or kitchen air or such

3) tossing bleach tablets into toilet tanks (toilet bowl cleaner tablets) - this and the next two are is the most likely to cause persistent smell of this type. (If it turns out to be toilet bleach tablets in toilet tank or sump pump pit I bet you will really kick yourself).

4) pouring bleach into crack around basement slab or into sump pump pit to kill odor coming up from stagnant under-slab water or moisture

5) pouring bleach into a floor drain that was smelling because the trap dried out from lack of use while house sat vacant. Don't forget basement or garage drain too - flushing with a couple gallons of hot water should clear it out readily. Ditto possibly if you have a foundation drain system (basement underslab or outside the foundation) or outside drain wetwell - if it was smelling because it was stagnant conditions maybe they dosed it with chlorine or root killer or such - remove cleanout cover and smell.

6) pool chlorination system leak or overdosing the pool - which considering you can smell it outside might be a good place to check - even shut and turn the chlorination system totally off for a day or two to see if the smell goes away. Also, if you use powder or tablet chlorination check where it is stored (and pool acid storage too) to be sure it is not leaking or dry hypochlorate is not getting wet and releasing chlorine gas

7) overchlorination of hot tub or spa

8) using chlorine-based dishwasher detergent, which then gets into the kitchen air as the dishwasher vents during operation

9) if possibly ozone, rather than chlorine (the biting sharp smell some electric motors and transformers and brush-type motors put out), then check around any electric motors you have - furnace blower, water or sump pumps, "instant on" hot water recirculation pump, A/C, furnace blower, reefer, doorbell or furnace/boiler transformer, etc. if from this source should be sharply stinging to the nose and much more evident near the motor when running, and of course turning off for a day or so should stop the smell.

10) water contamination or over-chlorination - smell and taste the water to be sure it is not something carried in the water

11) if on septic, open (or have opened) septic tank hatch to smell if it is from chemicals in the tank/leach field - maybe they dosed the heck out of the field because it was smelling from lack of use, or dosed it with a chlorine-containing root killer chemical

12) if smell is possibly plasticy (is that a word ?) it could be an overheating electronic device power supply (most are constant-on) or electronic device transformer or charger putting out chlorinated or other chemical smell as it overheats. Also smell around outside meter box and breaker panel - overheating electrical insulation can smell like this because they are commonly (especially for your higher-voltage main feed wires, especially black insulated ones) made of chlorinated compounds in the insulation on the wire

13) smell around in attic and basement/crawlspace for mold/ mildew, rot, or funny smell from insulation

14) look around for a hidden spot you do not know about - in-wall storage, under-stair cubby, attic (including possible separate attic over garage or such), utility closet bins or cabinets, fruit cellar, wall safe etc which might have leaking chemicals or rotting food or such in it.

15) rotting wood can smell like this - some fungal growth can be quite acidic smelling or astringent - usually due to a leaking pipe or shower pan or toilet wax seal, commonly in subfloor under tub or shower or toilet. Can also happen with wood foundation elements constantly wet. Normally going to be much stronger in basement, crawlspace, or just one room where the damage is concentrated.

Since you say can be smelled from outdoors before coming into house, couple of other possibilities:

16) ask neighbors if they have the smell and if so have they had any luck in tracking it down

17) check around your property line when air is almost calm (evening usually better as many odors tend to hang low when cooler) for possible source one a neighbor's property - pool/spa/hot tub chlorination or ozone treatment unit most likely source

18) ditto to above, for possible hot insulation or ozone from neighbor's A/C or such

19) on day with slight steady air drift across your property (from different direction for each side of property) stand at property line and smell if you can smell it coming onto your property from elsewhere - could be from chemical plant, refinery, water or sewage treatment plant, public swimming pool, etc upwind of you - though unless you are in an area where the wind direction is very constant you should have noticed some days with worse smell and some with near none, and of course should have been as or more obvious when out in yard or on deck or such than when inside. Obviously, with slight drift air across property, if stronger at property line that at house or same then almost certainly coming from outside your property. If always stronger at house or immediately on downwind side of house, then sourcing at or around house.

20) On day of closing when you noticed the smell - I presume you had not moved in yet - but if you had or were doing so at that time, look for spilled or leaking (maybe a bottle cracked during moving) cleaning or laundry products, or garage/yard solvents or such

21) walk around perimeter of house and smell along the way - some people just dump their unshippable household chemicals outside the foundation or under the deck/porch or down a sewer cleanout rather than properly disposing of them - which would be something you might be able to recover from the Sellers for investigation and cleanup costs if that was done.

22) oh - also if there was new flooring (including floor paint or epoxy) put in, smell that - it commonly outgasses a fair amount and is a very common source of this sort of complaint. Ditto if it was repainted and the primer or first coat (especially with oils) was not thoroughly dried before the second coat was put on, so it outgasses over a very long period. Can happen with interior or exterior paints.

23) large insect nests (termites, ants, beetles, bees, etc) can have a chemically smell - but presumably if people have been in the attic and crawlspace they would have mentioned an insect infestation if they saw it. A rotting cache of fruit or such from a resident varmint could also smell like this, as can birds nests because of the ammonia in the droppings.

24) remote chance - if your A/C runs on ammonia (R-717) or sulfur dioxide (R-764) which are usually only in commercial units but being used more in residential units now, could it be that ? Manufacturer label on outdoor unit would say what gas it uses - commonly R-22 (Freon), R-32, R-410a.

25) and don't forget, especially if strong outdoors, to check out plantings for odiferous plants - some people plant odiferous plants because they repel insects, plus some trees and shrubs are quite strong during seeding and blossoming time, if this is a new area for you or there are possibly exotic/rarer plants in the garden or flower beds.

You said HVAC system has been investigated - I presume that means the evaporator coil for the A/C and ducts were checked for mold/fungus ? A "stinky stock syndrome" coil or high-humidity ducts can smell to high heaven - hence the stinky sock name. Can range from an acidic smell to near-urine to wet wool type smell - though certainly should be able to identify that as the source if you air the house out thoroughly (including the area of the furnace or air handler blower) with the HVAC off, then smell at registers when you first turn it back on - should smell within a minute or less of when you turn it on if that is the cause, and smell stronger than the rest of the room did before it was turned on

Certainly if this smell was not there during your initial viewing or home inspection (home inspector would probably have noted it in report if that strong), then pretty much has to be something overheating causing the smell, or some architectural refinishing or cleaning or treatment or disposal that was done just before closing.

I would think if you air out all the rooms (all windows open while weather is still nice), then close all doors and HVAC system and leave all fans off, and block the gap underneath all doors with tape or towels, after a few hours of it being shut up you should be able to go through the house room by room and detect where the smell is strongest, then track down the source by nose from there.

Another trick (though not as good as getting down on hands and knees) is to clean your vacuum (works best with shop vac where the exhaust air comes striaght up to your nose easily), then while smelling the exhaust (ignoring the slight musty and ozone smells), run the vacuum hose over all trim, baseboards, under and around all appliances to the maximum extent possible, at all vents or registers, all concrete slab cracks, etc - to see if you can pin down a source point.

Before going to an air quality firm (going to be pretty pricey, though if that strong a smell testing probably will be definitive as to what chemical it is) you might consider a few more second opinions first - from friends or family, and/or from a Home Inspector and/or Plumber - both as a second sniffer to try to tie down where it is coming from, and also as a new (and with home inspector and plumber more experienced with manyu household smells) opinion as to exactly what the smell is from - is it cleaning product, chlorine, overheated insulation or plastic electronic device housing, flooring, paint, etc ? They might recognize the smell right off the bat from prior professional or personal experience.

Otherwise, an environmental firm to take air samples - likely one per floor plus backup samples, about $150-250 probably for the sampling (assuming you find a company local) and about $150-200/sample for basic common constituent identification or about $300-800 per sample for fully detailed contents and exact concentration for the lab work depending on specifics of the sample, which would usually use a mass spectrometer (MS) or gas chromometer (GC), or a combined GC-MS at a higher-end or larger lab that does a lot of samples in a year.

Please respond back if you would (using the Answer This Questions yellow button right below your question) with what the source finally turns out to be - I am real curious about this one.

Answered 3 years ago by LCD


Thank You LCD for your detailed you can imagine this issue is driving me a little crazy so am grateful for any potential ideas/help.

A few comments/additional details provided below.....

We did have a rodent infestation in the attic....prior owner had attic cleaned and sealed and we've had the insulation removed and replaced. To our knowledge (and from what the homeowner is telling us this is the ONLY thing that was done to the house while under contract). There was a chemical sprayed in the attic called Sporicidin. It's an FDA approved disinfectant that does not have a bleach smell. It's used to sterilize instruments in dentists office etc ---- we've spoken to several people at the company and feel pretty comfortable this is not the smell we are experiencing. In addition --- we do not smell anything in the attic and feel like we would given the smell is pervasive throughout the house....tell me if you feel otherwise.

The IAQ folks did not pick up any evidence of mold but I'm interested in your references to ozone. I've read where ozone generators (if used improperly) can result in bad chemical you have any experience in what that smell would be like and if it would last this long? To our knowledge there was no ozone treatment done but I'm just trying to check everything off the list I can. There was an entertainment center in the house that we gave to our handy man.....he put it in his garage and recently told us it smelled up his entire garage with the chemical smell!!!

Also ---- it is possible/plausible that the chemical smell would have contaminated our air ducts and continues to contaminate the house? We've had them professionallly cleaned but could the smell be ducts themselves. The older part of the house has metal ducts and the newer part has flex. It's hard for us to determine if the source(s) of the smell are throughout the house or just being picked up by the HVAC unit and distributed throughout.

We have a pool in the backyard but just don't believe that's the source.......we just had it resurfaced so the pool has been empty for a few weeks and the smell remains.

We do have a leak in the slab part of the house.....water has been shut off as we determine best way to repair ------ just don't think that could be causing the smell.

We've had no less than 10 people take a look at the issue (contractors, fire department, IAQ experts, pest control, plumbers, hvac). All have said they believe the smell is chorine /bleach based. Plumbers and pest control tell me no smell underneath the house........attic does not have a smell and if it was originated from the attic would think the smell would be very strong up there??

IAQ expert kept coming back to the prior owners treating the unit with bleach (they tell us they never did that) and we've run vinegar through the condensation lines on both air handlers. (One point of interest --- we cannot find where the one condensation line terminates.....think it may be under the house but even HVAC guys could not locate).

Open to any other thoughts/ideas...thank you!

Answered 3 years ago by broderbund


I sympathize with your problem - other than the thoughts I gave before, here are follow-up ones resulting from your reply:

1) in attic, wearing gloves and dust mask and washing self and clothing well afterwards, I would locally pull back the insulation in the area where the rodent infestation was and smell under the insulation and at any gaps in the plastic sheet vapor barrier (if you have one under joists and on top of underlying ceiling drywall) - possible urine or disinfectant left untreated under insulation (if a large infestation) that is not noticeable in the attic because it was treated at the surface of the insulation but if getting into the house because it is trapped under the insulation and vapor barrier - not likely, but a possibility. The disinfectant usually dissipates within a day to a week per their website, but trapped in the ceiling drywall under a vaqpor barrier could obviously go much longer - though the descriptions of the smell is doctor's/dentist's office/hospital smell, not bleach.

2) ozone - is the major irritant in smog, so causes coughing and respiratory irritation and burning, and burning of eyes and nasal membranes in higher concentrations. Any prior ozone treatment of ducts or such would have dissipated within less than a day - ozone is a modified oxygen molecule (O3 rather than O2) that dissipates and breaks down quite rapidly and does not leave a residual smell. So any ozone you notice now, which does have a bit of a disinfectant odor but not really like bleach, would have to be actively generated by an electric motor in the house or powerline arcing. The former should be quite noticeable right at the motor, and is normally only generated by brush type motors (like many older motors and handheld rotating power tools like electric drills). Sniff around at ducts when blower is running (which is likely a brushless motor so not likely source), any constant hot water system circulating pump or heat pump like on water heater, sump pump, reefer or deep freezer when running, and fans when running. Should be far stronger right by the running motor than in rest of house - and would dissipate within an hour or few when off so to last 3 months would have to be a motor that runs quite frequently. But I just don't see it being able to fill the house and be smelled outside for the smaller household sized motors - unless you have (highly unlikely) an arcing transformer in your yard which has a constant arc that is not burning through so it creating ozone - would be a REAL rare case to last more than a few hours to days without burning out.

3) air ducts - if recently cleaned should be fine - if the flex ducts are creating the smell should be much stronger smell if you push your nose up tight to a duct (if coming from the plastic) or stick your nose into a supply duct or two after removing (usually just 2 screws) a floor register or two to get up-close. Could potentially be an odor from a previous duct mold killing treatment with a bleach product (which is not the right thing to use for that) - you could remove a register and do a damp-wipe inside the duct as far as you can reach and see if stronger smell - though might be hard to tell between a residual smell in the duct and smell deposited in the ducts during circulation of the air.

4) Pool - if chlorine disinfected, check storage of powder/pellets or gas tank as applicable, and check all lines running from chlorinator to system for leaks. You could also (after getting utility lines located) use a posthole digger or auger to open up a few holes in the yard around the house, particularly on the pool side and most especially if leakage drainage from pool (yours or neighbors) could be toward the house, cap the hole for a day with a tight-fitting plastic jug or such, then remove and smell whether the smell is strong in the ground, indicating highly chlorinated water leakage from the pool or chlorinastor to the house. Of course, walk the property lines to semm if the smell is coming in from outside your property - like someone "kill dosing" a pool that went south or started forming algae so they hit it with high chlorine and acid doses - or have a pool guy who does not know how to dose their pool.

5) Septic tank if you have one - do you use any sort of septic tank treatment or drain cleaner, or unusually large amounts of any disinfectant or cleaner in the house - though unless it was frequent use would expect that to dissipate within days, and would only apply if you were occupying the house before closing.

6) about the slab leak - unless chlorinated water was coming in, should be a musty, stagant water, or mildew/mold smell - easy to tell if source by taping down plastic sheeting (thin cheap painter's drop sheeting) with masking or duct tape, held up to create an airspace with a bucket or junk chair or such, then open up a side after a day and stick your nose in and smell if concentrated smell from that area.

7) condensate line - can't see that as a cause, but will need cleaning or replacement from time to time so I would either find out where it leads to or have it replaced/rerouted to a new known drain location - if not now, maybe at next coil cleaning.

8) One thought - smell at the condensate lines during several different times of day - remote possibility one or both is illegally lead to a sewer pipe connection that does not have a trap so you are getting sewer gases coming up through it.

9) Strong chlorine smell could also be from some industrial/commercial cleaner in the public sewers backing into your line and venting into the house through a faulty vent system or dried out floor drain. Could check by smelling at sewer vent pipe on roof - usually 2 or 3 inch plastic pipe standing up a foot or two without any cap on it, which vents sewer gases out of your household system. Can also check at an outdoor sewer cleanout (usually a standpipe with cap or plug a few feet outside house) to smell if any such smell there. Could also call (if on public sewer) the sewer utility and ask if they will check at their lines for such a smell - or you might be able to (without getting hit by a car hopefully) smell at the small hole that is usually in sewer manholes in the street or sidewalk.

10) Go around house and unplug every plugged in item you don't absolutely need, especially electronic devices and any chargers, air out house well, and see if that helps - then plug back in one at a time (maybe one a day) till it comes back. Of course, since you smelled it on closing day, only items that were there at that time are suspect.

11) Oh my - I forgot one very obvious possibility - does your HVAC system have any sort of mold killing ultraviolet light system or an electrostatic air cleaner - those can cause high ozone levels if malfunctioning. Or is there a portable air cleaner in use ?

12) Ditto to ozone or ultraviolet or chlorine disinfection units on any hot tub, spa, sauna, etc.- yours or neighbor's near your property line.

13) If all else fails, I would use plastic sheeting and tape and close up all room vents and exhaust fans, close and cover and tape all windows, power off HVAC system, and use cheap painter's plastic sheeting and masking tape to seal off every room (weighted at bottom to seal door bottom gap, like with board or such if carpeted - use tape if hard flooring), and let sit for as many hours as feasible (take a day out of the house on weekend say) then when you come back into house move from room to room smelling if there is a higher concentration in any one, or if smell burst out when you untape the duct registers.

14) and as I said before, talk to neighbors about whether they have had their hot tub or pool treated or disinfected (though for it to persist 3 months would have to be a persistent dosing), septic leach field pipes cleaned/disinfected 3 months ago, or if they have noticed the smell also with wind blowing from any direction but your house, so might be a nearby laundry or institutional laundry room or hospital or chemical compnay plant venting or such.

15) one other thing I spaced on - do you have a water treatment system (water conditioner) which uses a disinfectant in its cycle - like hypochlorate for example, which may be leaking or venting into the house. Or a neighbor's unit, especially if in outdoor utility closet if in non-freezing area.

16) not that it smells really like bleach, but if gas water heater or furnace, smell at the exhaust flue on roof, or outdoors if direct-vent unit (just a few sniffs - don't do for long and suffocate yourself or pass out) to smell if it is exhaust smell from those appliances - if so, you may have a backdrafting vent hood at the unit, or a flue leak. If backdrafting you should smell the odor at the unit when it fires up.

17) one last option - don't really smell like bleach to me, but some wood funguses do have an astringent, sharp, very chemically smell - so could be significant wood rot from a leaking pipe in the house - though would not expect that to be detectable very far outside the house if at all.


I am really somewhat at a loss, because since you did not notice it during how ever many times you were in the house before closing day (initial viewing, home inspection, etc), but did notice it on closing day - has to be something from outside, something inherent in the house itself, or something you moved in before closing (assuming you had not yet moved in and were not living in the house at that time) - so if it was a bare house that really narrows the list of possible sources, and there are very few in-house things that could cause this for months without either dissipating or burning out, so I am tending toward:

1) the pool (yours or neighbors) or any spa/hot tub/sauna having excessive disinfection (or an ozone or ultraviolet disinfection unit),

2) chemicals in the sewer system getting into your house, or

3) unshippable chemicals dumped by the previous owner outside the house somewhere, or into a drain - especially if on septic, though the right solvents poured down drain could have melted through plastic pipe and caused formation of a pool of waste chemicals in, under or outside the house.

If not able to tie down the strongest odor point by (preferably several people at same time) walking around all areas and sniffing, and failing a result from that then individually sealing and then later checking the rooms, then certainly the environmental testing firm taking air samples and running lab tests would I guess be your only remaining optionother than jacking up the mailbox and slipping a new house and lot in underneath (a variation on jacking up the radiator cap and slip a new car in underneath). And be sure they take an adequate number of duplicate samples so if the cheaper GC test does not pop up an obvious strong hit or cannot identify it, they already have samples at the lab to run a full GC/MS test - though $500-1000 is not unusual range for that in small quantities for one customer because they make a killing off blood and urine tests for drugs so the cost has doubled or more in recent years.

I have not mentioned them using a handheld Drager sniffer or similar because I have low hopes that will determine the chemical responsible nor the source, though it is possible it can identify the class of chemical - but if a bleach smell, handheld unit might just give a hit for chlorinated compounds and certainly you will still need GC or MS or GC/MS testing to identify the exact one - which unfortunately STILL does not tell you necessarily the source or the exact product, because for say a chlorinated cleanser or phenol disinfectant there are still a bundle of products which could have released that chemical.

Please do let me know what the cause ends up being - you now have me irritated by this issue and in anticipation of the result for this too.

Answered 3 years ago by LCD


Ok - now you've got me going obsessive on this problem - couple of other thoughts came to mind, though I would not call them necessarily "bleach" smell, but definitely strong chemical smell:

1) low gas level in A/C can cause scorching of the oil in the refrigerant gas which, if you had a leak in the lineset or evaporator coil or have an outdoors air handler unit, could get into the house on a persistent basis - I would call it an oily or acrid burnt smell more than chlorine, but different people call smells different things depending on their personal experience. Like people who cook a lot describe irritating household smells by different spice names, ones I have never heard of.

2) just to be sure - you did say several people smell it, right - so it is not just one person's sense of smell gone haywire, right ? Called Phantosmia (phantom smell) and associated with several medical conditions as well as the famous "deja vu" where just kicking up a memory brings back a smell or sound or taste - but obviously if multiple people smell it not that.

3) flex dryer vent in clothes dryer partly disconnect so it is getting scorched by the hot air coming out and stinking (melted plastic smell)

4) heater element in dishwasher staying on all the time, overheating plastic and causing it to stink. Obviously, should smell strongest at dishwasher and unplugging it and not using it for several days should dissipate the smell.

5) electronic device (TV is a common one) with overheating power supply (which is usually always on) causing hot plastic smell, which can include chlorinated or brominated products - as in prior comments, unplug electronic/electrical devices and leave unplugged for several days

6) scorched guts in a microwave or toaster oven or such

7) of course as mentioned before, smell at breaker box and around outdoor electrical boxes for possible overheating/burning insulation smell

8) halogen, CFL, LED, low-voltage, track lights - check at each of them or swap out bulbs one by one temporarily - when they or their transformers start overheating can cause a real nasty strong chemical smell. I had two brands (Sylvania and Green something, may have been made by same plant) CFL bulbs I sent back because even in normal use inverted in can track lighting which they were rated for, caused overheating and scorching of the bulb base and nasty chemical smell

9) inverted light fixtures, especially with normal incandescent bulbs (which get hotter), causing burning of the wiring up in the fixture - initially overheated or burning wire insulation, which can transition to a direct short of the exposed wires.

10) failing photocell or starter circuit on outdoor lights getting hot and causing burnt plastic smell - woudl smell outside plus possibly coming in through wall to inside.

11) again getting back to what was in the house on closing day so may not apply, but intermixing or leakage of solvents, paints, perfumes in storage/garage/workshop, or some chemical in a container (particularly urethanes and resins do this) going bad in the can and leaking odors as it changes chemical composition. Ditto to leaking containers that rusted through the bottom of the can and is vaporizing or maybe reacting with the shelving material. Did the owners leave any paint cans or spray cans or anything that could be leaking in the garage or basement ?

Answered 3 years ago by LCD



Thanks for the follow up thoughts.......

I'm coming around to the idea that there had to be a combination of inappropriate chemicals which continues to give off a chemical gas.

We know for a fact the prior owners contractor used Sporicidin after the pest control man had sealed and trapped in the attic. We contacted the pest control guy and asked "if he had sprayed anything in the attic" during the process and his answer was he only sealed and trapped.

Perhaps bleach had been sprayed in the attic before and the Sporicidin reacted when it was sprayed down. I've read some pretty scary scenarios on the web and it does create a very strong chemical smell which is absorbed into clothing, furniture, etc.

Let's assume worse case scenario that this in fact is what transpired.....what are we looking at in terms of remediation? Can the wood attic floor be sprayed with a neutralizing chemical? would we need to replace the entire attic, tear the house down (please dont' say yes to this question!!)

We hope to get the environmental folks out this week....I'm going to ask them to test for Sporicidin and Bleach in the attice.....if they are able to drill down to that level of detail or detect the gas that is ommitted from coming phenol and bleach we'll know our isssue.....

The question becomes....what do I do next???

Answered 3 years ago by broderbund


Rambled a bit as I added things - so I would recommend reading all the way through, especially to bolded part near end, before doing anything based on this input.

Sounds like, if none of my suggested causes makes sense, that an Environmental Health Survey of your house is necessary - by an occupational/industrial or environmental health specialty company - commonly they are Civil engineering firms or Environmental Science firms like SAIC because generally perform this service on hazardous waste and abandoned industrial or military property sites.

Oh - one thing - you said IAQ expert was in attic - did he/she check out the rest of the house, and was the smell noticed/identified by that person ?

The thing that throws me, and why pool/spa chemical or hazardous waste or sewer gases coming from the street or odors from some business (or neighborhood illegal drug lab maybe) drifting into your property moved to the top of my list, is the long-term persistence - because for the odor to persist and permeate your possessions, it would normally have to be active - meaning liquid or gas from usually unless it really pearmeatedthe entire house (like fire or cigarette smoke does) - and something done 3 months ago I find that hard to believe in usual cases unless gallons were poured into the drains or ground or such.

Also of course, if it was smelled at closing date walk-through, and same smell and approximate persistence now, I would be making a strong effort (if previous owner will cooperate) to talk with any contractors or cleaners who were in the house about what they used - anything from wall washing or carpet cleaning solution to repainting. Look at any items that were on contingency list to be done by the contractor - could any of those projects have caused the smell. In particular, was there any mold removal or waterline or water heater (though latter two would be smelled in the water if strong residual) disinfection done - either to kill algae in lines/tank/well or such, or to disinfect significant pipe replacement project (new water lines are disinfected before put in use).

Also - you have said neither you nor IAQ inspector detected odor in the attic or other contractors in crawlspace - so I am afraid attic is not likely to be the source, both because if it is not detectable there at all why is it so strong in the house, and also if it originated there (assuming an outdoor vented, not fully finished attic that is part of the "conditioned space") the vast majority of the odor and the direction of airflow would normally be out of the house through the attic to outdoors through ridge or gable vents or roof ventilators or such, not from attic to indoors - so pretty unlikely to be getting indoors in high concentration from the attic even if spread all over up there.

You did not say what type of insulation you have - is it possible chemical was sprayed on a foam insulation that it reacted with ?

Don't fail to pay attention to the possibilities in 6) - did not mention them before because rare, but possible - and the illegal drug lab possibility has come true for about 150,000 buildings in the US so far, so a possibility, especially if the house was vacant for a period.

My I guess final, last-thought suggestions:

0) one suggestion I did not make before, which might be done along with checking for the odor in the sewer lines at cleanouts if the odor is detected in them, is to follow up with a smoke or odorant (commonly vanilla or banana oil is used) test by a plumber of the plumbing system - to determine if you have leakage from the DWV (drain waste vent) system into the house.

1) assuming you rule out the other likely causes from my suggestions, go ahead with the environmental health assessment but I would suggest only after talking to lawyer per 5) below. This assessment, which I expect will total in the thousand or two range assuming no gross contamination, will likely (at least way I would do it) involve possible on-site wipe samples tested onsite with a "shake and bake" chemical family identification kit to determine what class of strong contaminants are present on surfaces in the attic (done with wipes which are then put in test tube with different chemicals to identify class of contaminant) and maybe in ducts and on walls as well, and possibly by using a "Drager Air Pump" or similar sampling tester which pulls air into a handheld test machine to react with specific identifier tubes of chemical to determine the class of the contaminant - this is wha tis generally used by fire departments and major chemical spill first responders to determine what contaminants are coming out of fires or transportation spills.

Neither is definitive as to the specific chemical present though - that requires sealed samples taken to the lab for detailed chemical analysis, as I previously described. Unfortunately, because this sort of investigation can run quite an expense (I have been site supervisor on commercial/industrial/military sites where even the initial source and gross class identiification ran million of $), it is normally done incrementally - a couple hour initial classification/detection run, then depending on results of that perhaps more detailed sampling with wipes, then if appropriate detailed GC/MS testing of samples in a lab, then site assessment of the extent of copntamination once the nature of it has been determined (so on-site rapid detection chemicals can be used to map out the extent), then a remediation plan done, then the remediation, then the confirmation testing to prove it has been cleaned up, then possibly some additional cleanup for areas not adequately cleaned.

2) If I were them I would also take an organic chemical sniffer (OVA - Organic Vapor Analyzer or similar) around the outside perimeter of the house and adjacent yard area to detect any concentration of spilled chemicals, to rule out (or confirm) that source. Could also detect (if odor is if strong at time of inspection, which you need to discusss up front mid-dauy or such visit time to catch at usual strongest time) - if drifting onto property from adjacent area.

3) If doing the investigation, i would also be looking at title data for historic ownership and uses of the land and adjacent areas - against the chance this is a leak from either a previous industrial site, a FUD (formerly used defense site), or could be getting contamination from adjacent plant or facility. And whether a certificate of drug manufacturing hosue certificate (not required in all states) is in the title files or police files indicating this was a drug lab that was cleaned up (perhaps not properly) in the past. Though the fact you and the home inspector during purchase (if you had an inspection done) did not detect the smell at that time - which could mean it was wide open windows and airing out when you were there (which would imply owner know about the issue and failed to disclose it) or that possibly it was something going on after your offer and inspection and before closing - a vacant house presenting an opportunity for just a day or few of illegal use.

4) Cleanup - highly unlikely house would need tearing down, or even major rebuild of attic or wherever the source is - usually in-situ remediation can be done with extensive scrubbing down and/or spray-on chemical treatments. Worst case is usually ground/groundwater contamination cases where excavation around/under foundation and/or basement slab and sealing to prevent odor infiltration, and even that generally does not involve tearing down the house.

5) Because of the need for documentation and proper independence of investigations, and possible dealings with the police and local government if the odors are from prior illegal drug manufacturing in the house, I would (I hate to have to say it but for your own good) strongly advise getting an attorney experienced in contaminated property claims and issues on board BEFORE getting an environmental health /industrial health investigator in - to work with them on documentation in the event you end up having cause to go against a previous owner for non-disclosure of something he/she knew about.

It is also possible, if prior drug lab use is a viable likelihood, that the attorney will recommend asking the police if they will do a meth test on surfaces in your house - but that brings in the possibility of case 6 b) below with police condemnation of the house, at least till it is investigated and has been cleaned up to whatever local or state standards your area might have. Another alternative he may recommend before a complete environmental assessment of the house is hiring an environmental cleanup firm that specializes in cleaning up after illegal drug labs to do an on-site walk-through just to test for the most common drugs (meth, crack, heroin, cocaine and such) and to assess whether it looks/smells to them like a drug lab situation. Of course, that type of contractor would have police as at least one of it not their most common customer so if the answer is yes, they will undoubtedly inform the police - probably required to by law, so your attorney should be present during the walkthough to contact the police on your behalf first before they hear about it from a third party.

Feel free to show this blog to the attorney for his use - not professional nor legal assessment or advice on my part but might have a thought or two of possible use to him/her, since I have been through this sort of assessment numerous times before.

6) You did ask (rightly) what possible worst-case scenarios after assessment are - and bear in mind, these are worst-case but FYI, as I see it, from roughly lesser to greater consequences :

a) they find a very hazardous substance or chemical concentration and you have to move out for days, weeks or months till it is remediated - normally heavily cleaning or rarely stripping the affected area only like attic floor maybe, and usually all fabric wall or floor coverings and any exposed insulation involved. In cases where the house surfaces are permeated it can involve stripping down to the studs (usually all loose insulation and flooring and such in area is discarded), chemically neutralizing the situation, then refinishing/ repainting (sometimes with an encapsulating paint) or rebuilding as needed.

If it is strong enough that it permeates the clothing within 15 minutes of being in the house, personally I would not have been staying there at all, from a personal health standpoint, and absolutely not if any child or person with known significant medical issues in the family who could be affected - and I would not be in the least surprised if a temporary moveout during the investigation is what the environmental contractor will recommend as soon as they smell it too if it is that strong and permeating.

b) they find a quite hazardous condition or that it was an illegal drug lab and, legally having to report it to the state or federal drug agents or EPA, your house is condemned - at least initially until it is cleaned up. Like chemical spillage from a meth or other drug lab that was run there while it was vacant or such - is there any chance of that ? - you can google for the smelll from that, but usually ammonia or wet diaper/urine smell, rotten egg smell, ether, auto parts cleaner, non-perfumey sweet sticky smell, iodine, acetone, etc. Bleach smell is on the general meth or drug manufacturing chemicals list for processing and for cocaine/heroid processing too - but could as well be present if used in high concentrations to try to remove the other odors. Articles on that below - you can google for more info on smells from meth labs -

c) or in cases of major contamination (almost always from gross area-wide soil/groundwater contamination) sometimes permanently condemned and then remediated under CERCLA or RCRA or such (remember Superfund and Love Canal, which started this way with groundwater-borne gas infiltrating into the houses and causing illnesses). You did not say if you are adjacent to industrial property with storage warehouses which might have leaking chemicals, a chemical plant or water/sewage treatment plant or laundry facility or such which could be leaking or illegally disposing of chemicals, or a landfill which could be leaking or discharging odorous materials.

Though talking to your neighbors - WHICH I THINK SHOULD BE YOUR FIRST STEP NOW IF NOT ALREADY DONE - should tell you if there is a neighborhood source of that odor which could be doing this. If possibly so, you might invite a couple who seem safe (i.e. be cautious you do not invite neighborhood drug lab operator over to talk about his lab's smell) over to smell around your house and see if it is a local odor they recognize. For instance in our area the local landfill started extracting and burning for power the methane coming out of it - but even though a mile or more away, commonly in the summer the odor of the burning gas and the associated phenols and partially burned gas odorant added to it can be highly obnoxious (though smells like rotten garbage or a natural gas leak, not chlorine bleach) - enough so that the local natural company is going crazy with callouts for people thinking there is a natural gas leak in the area.

Answered 3 years ago by LCD



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Answered 3 years ago by Member Services


I did not answer to your follow-up misapplication of chemicals question, hoping someone else would pipe uo and contribute - unfortunately even though I commonly leave questions I could answer for several days in hopes someone else will contribute, in a vast majority of cases no one does - as appears to be your case.

The firm doing the testing, assuming they are an industrial or environmental health firm, should also be able to (and should volunteer to do) develop a remediation protocol (cleanup procedure) and cleanup and confirmation testing plan, once they know what the problem is.

Common contaminated surfaces cleanup modes for your sort of case, assuming an in-house contamination source (as opposed to groundwater contamination or buried waste or drifting-in contamination or such):

1) commonly, a bleach or hydrogen peroxide or solvent or borax (depending on chemical) cleanup protocol is used, using "wet-wiping" techniques - like mopping all surfaces, commonly with either a second person following to wipe up the excess liquid after a short exposure time, or sometimes vacuuming the remnant up - usually followed by normal detergent wash using TSP to remove residual and the cleaning chemical.

2) for chemicals/odors infused in absorbent surfaces, wand spraying with a liquid neutralizing agent can be used - or sometimes for agents which will volatilize in heat, steam or heat gun is used (later rarely because most such compounds are also flammable or corrosive when heated). Ozone generator is sometimes used (most commonly for smoke odor from fire (accidental or heavy wood stove/fireplace use) or from tobacco use - it can eliminate odors from a range of organic compounds if it reaches to it, so normally circulated through the air duct system to reach all areas. NOTE - it is important that if the ducts are used for this, it should NOT return through the furnace/air handler - can cause significant damage. Should be injected downflow of the furnace/air handler fan, and be exhausted at the end of the return duct - the furnace/air handler itself should be pulling fresh air from outside only through temporary fresh air duct feed so the ozone does not pass through it. Ditto on any other combustion device - ozone can corrode it in quantity and especially in hot areas, so they should be shut off (but left open to be decontaminated) during the treatment.

3) rarely, where highly infused in a material, replacement. That is generally limited to carpets and heavily contaminated unwashable curtains, rugs, mattresses, unfinished rough wood or fabric wall coverings, and the like. Usually, unless drenched in the stuff, furnishings and clothing and such are commonly readily cleanable, though some may take dry cleaning rather than laundering to remove it. With some types of contaminants, again generally if actually saturated with the chemical as opposed to just exposed to airborne contamination, replacement of absorbent countertops, flooring, etc is necessary.


Commonly on the order of $0.05-0.25/SF with higher end usually being only for the directly contaminated surfaces, lower end for secondary contamination and areas where airborne odors are sticking.

Answered 3 years ago by LCD



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Answered 3 years ago by Member Services


Personal experience! I was using metal electrostatic filter on central air system. I started smelling chorine-like smell that increased over weeks until it was intolerable through out the house. I searched for answers and found conflicting opinions on the filters, ozone, and odor. I was desperate and replaced the filters with paper ones. Within hours the smell and burning nose got better and is gone this morning. I really didn't think it would work but it worked 100%. Debate or don't but I have undeniable personal experience after being very sceptical that the filters could be the problem. There you have it.

Answered 3 years ago by msm35


msm35 - excellent call. This shows the advantage of multiple responsders to questions.

An electrostatic filter does produce ozone - which is an acrid smell, and especially for people who have not been around high voltage equipment or opne-housing larger electric motors might be identified as a bleach or chlorine smell.

Answered 3 years ago by LCD


Did you ever find the sour of the odor? we have the EXACT thing going on in our house, but no idea where it is coming from or how to get rid of it. We go out to the store and people comment about how they smell chlorine or fertilizer. We've had A restoration company come and say it smells like ozone but cannot find a source. Air out for days and think its dissipating, but within hours of closing up windows you can smell it again. So frustrating!

Answered 2 years ago by BaggyJ


Don't know if original poster will check this as it's a couple of years..

OK, I had mold growing behind my medicine cabinet. It was on an exterior wall creating a vapor barrier. My eyes were getting red and swollen everytime I opened the cabinet. I got a whiff but couldn't comprehend it being's all mirrored and metal. We took down the medicine cabinet and it smelled really bad. No visible mold but slimy smelly. goo. Cleaned it several times, several ways and it still smelled. I happened to have an extra container of "Biocide's Room Shocker". We used it in guest bedroom when tennis student left their smelly gear there. Room smelled afterwards. We followed directions and it worked. Light smell of chlorine but washed walls, aired out and it was fine. I am mildly chemcially sensitive and have the nose of a dog. A friend's parent tried the car shocker from nasty mold growing in car from getting rained in ooops those back windows. It was bombed overnight, aired out from chlorine smell and then neutral. Well..... tried it in the master bedroom vanity area and left it an extra day as I can't be exposed to it with my sensitivities.

It's been 7 weeks and the chlorine smell is still there. Walls also washed several times, several different ways. The vanity drywall was replaced and painted. The master br was painted with Sherwin Williams Harmony odor absorbing paint. That was last week. Im hoping it is slow to dry as have not been able to air out...only ac is running. I am not living there. Im afraid I may have to replace drywall.... Anyway it's probably chlorite. It smells like chlorine and is the byproduct of chlorine dioxide...Biodcide's Room Shocker. I haven't read anyone else writing about residual chlorine smell. I wonder if it's from several Chinese sources with no quality control. Yes, I did use it a day extra but Im sure others have as well and posted as much.

Answered 2 years ago by IAQwish


I know it's been awhile but have you been able to get rid of the problem and/or determine the cause? if it's from what I think it is, then it's undoubtedly still there. it may be due to a rare metal contaminant, osmium, (or ruthenium) which is not considered by many testing facilities or the facility doesn't have the capability of testing for it.

Look around for some signs:

yellowing of white plastic, especially coat hangers.

deposits of round specs of pitting corrosion on stainless steel, easily confused with mold. (amorphous reduced osmium is black but it can also be a red-brown hydroxide confused as iron rust.)

golden tiny crystals of crystallized reduced Os on the floor, especially days after cleaning the area with bleach.

bright red lustrous specs, especially days after cleaning the area with amine based cleaner (and turns golden with acids)

--a brief background about osmium. If not crystallized at high temperatures (3000C) without oxygen, this element will slowly oxidize into a chlorine-like smell, instantly react and bind to organic matter and all types of metal, only to be re-oxidized by humid air and repeat the process. Almost all compounds formed are volatile and great effort is required to stabilize them. Os is also oxidized by humid air in a strong and weak basic environment While weak acids will slowly pump any oxidized Os into the air and strong acids will do so instantly. However, reduced Os is stable in strong non-oxidizing acids.

Answered 5 months ago by Thetodor


I have a similar problem. But I've been living in my apartment for 14 years, and it started suddenly about a week ago. I don't have anything fancy in my apartment. No central air (also, it's winter) no dishwasher, no pool. It doesn't smell like bleach exactly, but like strong cleaning agents. Like ajax or comet powder. The direction it's coming from is under the sink. There's no leak, no visable mold. But again, it doesn't smell like garbage or mold. But like strong cleaning agents. It smells toxic. I don't know what to do.

Answered 2 months ago by alwayz

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