Symptoms better away from home? What it can mean

Do you feel better on holiday, at work or outdoors, and worse again soon after you come home? Then the building you live in is one of the first things to look at.

Symptoms that improve shortly after you leave a building are the defining feature of “sick building syndrome”, as the US Environmental Protection Agency (EPA) describes it [1]. The usual causes are dampness and mould, poor ventilation, chemical emissions (VOCs) and allergens.

Sometimes the symptoms spread across many body systems: fatigue, brain fog, aches, sensitivity to light. Then chronic inflammatory response syndrome (CIRS) is one possibility worth discussing with a doctor.

The pattern alone does not tell you the cause. This article explains what it can mean, how to test it step by step and what to do next.

Why do I feel better on holiday and worse at home?

Several quite different things can produce the same pattern:

• Something in the indoor air. Dampness and mould can cause symptoms that are tied to one building. So can chemicals released from building materials, furniture and cleaning products, and poor ventilation [1][2].
• Allergens. These are substances that trigger allergies. Dust mites, pet dander and mould are common indoor allergens. If you are allergic to them, a home with more of them can make you feel worse.
• Things that have nothing to do with the building. A holiday also means less stress, more sleep, more daylight and exercise, and different food. The EPA notes that complaints may also come from illness caught elsewhere, allergies, job stress and other psychosocial factors (things in your life and mind) [1].

That last point is not a reason to dismiss your experience. It is a reason to test it properly. Then you and your doctor can tell the explanations apart.

What could be causing it?

Possible cause	Typical symptoms	Typical clues in the building	How to check
Dampness and mould	Blocked nose, cough, wheeze, asthma, eye and skin irritation [2]; in some people fatigue and brain fog	Musty smell, stains, peeling paint, past leaks, swollen floors	Moisture and indoor air inspection by a qualified inspector
Chemical emissions (VOCs)	Eye, nose and throat irritation, headache, nausea [3]	New furniture, renovation, paint, flooring, cleaning products, fragrances	Remove or air out sources; inspection; VOC measurement
Poor ventilation	Headache, tiredness, difficulty concentrating [1]	Stale air, condensation on windows, rooms that feel “heavy”	Check that ventilation works and is set correctly
Allergens (dust mites, pets, mould)	Sneezing, runny nose, itchy eyes, asthma	Pets, carpets, old bedding, high humidity	Allergy tests with your doctor
CIRS	Symptoms in many body systems at once: fatigue, brain fog, pain, light sensitivity, numbness, frequent urination, temperature regulation problems [4]	Usually a water-damaged building	VCS test and the CIRS diagnostic process with a doctor

VOCs (volatile organic compounds) are chemicals that evaporate into indoor air. Several causes often occur together. A damp house may also be poorly ventilated, and mould is itself an allergen.

Can it be CIRS?

CIRS is described as a chronic inflammatory illness of the innate immune system, the body’s fast first line of defence. It follows exposure to the indoor air of water-damaged buildings and causes symptoms in many organ systems at once [5].

How is CIRS different from sick building syndrome?

The two differ in one important way: what happens after you leave the building.

• Sick building syndrome: symptoms are expected to ease soon after you leave [1].
• When an illness has become more than irritation: recovery after leaving can take longer. The EPA notes this for building-related illness in general [1].
• In the CIRS model: the inflammatory response can continue after you leave. So a short holiday may bring only partial relief.

What happens when people go back?

One small study Re-exposure is another clue. In a small study by Dr Ritchie Shoemaker’s group, people whose symptoms had improved with treatment fell ill again within one to seven days of returning to the water-damaged building [6].

The study was small: 19 people completed it. Its participants were not randomly selected. It was not blinded either, so everyone knew who went back into the building. It shows a pattern seen in that group, not proof.

When is CIRS worth considering?

CIRS is worth considering if:

• your symptoms are in four or more body systems, not just the nose and lungs [6]
• you have cognitive symptoms (problems with thinking) such as brain fog, poor memory or difficulty finding words
• the illness began in, or worsened after moving to, a building with water damage
• other common causes have been looked at and do not explain it

Read more about the symptoms of mould and water damage and how CIRS is diagnosed.

How can I test whether my home is the problem?

You always know where you are, and what you expect can colour how you feel. So your own observations will always be somewhat uncertain. A step-by-step approach still makes them much more useful.

1. Keep a symptom diary

2. Plan time away, and come back

Spend at least a week or two somewhere else, preferably in a building with no known water damage. Keep the diary going. Then return home and keep recording.

The most telling pattern is improvement away and worsening after you come back. If you can, also spend a few nights away during an ordinary working week. That separates the building from the holiday effect.

A review of illness from water-damaged buildings advises avoiding not only the buildings but also items contaminated in them [7]. So if you take clothes and bedding from home with you and feel no better, that does not rule out the house.

3. Have the building inspected

A professional moisture and indoor air inspection is the most important single step for the building. A review of sick building syndrome in The Lancet calls an on-site assessment of the building extremely useful [8].

A good inspection includes:

• a history of leaks and repairs
• moisture measurements
• opening structures where the risk is high

Our water damage guide explains how inspections work. If chemical emissions are the more likely cause, see volatile organic compounds (VOCs).

What do ERMI and HERTSMI-2 tests tell you?

Many people with suspected mould illness are advised to order a dust test. These tests analyse a sample of dust from your home. It helps to know what they can and cannot do.

What does research say about ERMI?

Preliminary research In a US birth cohort, a group of children followed from birth, children whose homes had a high ERMI score at age one were more than twice as likely to have asthma at age seven [10].

However, in 2013 the EPA’s own Inspector General, its internal watchdog, found that commercial firms were using ERMI. The EPA had not validated it for public use [11].

How is a HERTSMI-2 score read?

Expert opinion HERTSMI-2 uses five of the ERMI species to estimate whether a building is safe for someone who has already been made ill by a water-damaged building [12]. On its scale, below 11 is considered statistically safe, 11–15 borderline and above 15 too risky [12]. Its developers note that it does not replace careful observation of your symptoms after re-exposure [12]. We found no independent studies validating it. Read more about the HERTSMI-2 test.

What are the limits of dust tests?

• A dust sample shows only the dust. It reflects settled dust in the sampled rooms, not damage hidden inside walls or floors. A low score does not prove that the structures are dry.
• Measured microbes predict health less well. A review of the epidemiological evidence found that microbial agents measured in dust were less consistently linked to health than visible dampness or mould. It did not support using such measurements to guide health decisions [2].
• Doctors usually do not need them. A German medical guideline review says that indoor measurements of mould, microbial volatile compounds or mycotoxins are generally not needed for the medical evaluation of a patient [13].

Dust tests can still be useful as one piece of evidence, especially when you compare buildings. They do not replace a building inspection or a doctor’s assessment.

What should I do next?

How strong is the evidence?

Well studied That dampness and mould harm respiratory health is well established [2].

Symptoms that ease away from a building point to the building. This is the basis of the EPA’s description of sick building syndrome [1]. But the pattern itself does not identify the cause.

Preliminary research The evidence for CIRS is weaker. It comes mainly from small studies and case series by Shoemaker’s group [6] and from reviews by clinicians who treat CIRS [5]. Dust tests such as ERMI and HERTSMI-2 have clear limits [11][13].

The practical conclusion is the same whichever view you hold. If your symptoms follow your home, investigate the home and your health in parallel.

Remember these

Check yourself: Why is a few nights away during a working week more telling than a holiday? And why does a low dust-test score not prove that the walls are dry?

What next?

• Read about mould exposure symptoms.
• Count your symptom clusters with the CIRS symptom checklist.
• Learn how a water damage inspection works.

References

1. US Environmental Protection Agency. Indoor Air Facts No. 4 (revised): Sick building syndrome. February 1991. EPA (PDF)
2. Mendell MJ, Mirer AG, Cheung K, Tong M, Douwes J. Respiratory and allergic health effects of dampness, mold, and dampness-related agents: a review of the epidemiologic evidence. Environ Health Perspect. 2011;119(6):748–756. PubMed
3. US Environmental Protection Agency. Volatile organic compounds’ impact on indoor air quality. epa.gov
4. Shoemaker R, Johnson K, Jim L, Berry Y, Dooley M, Ryan J, McMahon S. Diagnostic process for chronic inflammatory response syndrome (CIRS): a consensus statement report of the Consensus Committee of Surviving Mold. Internal Medicine Review. 2018;4(5):1–47. PDF
5. Dooley M, Vukelic A, Jim L. Chronic inflammatory response syndrome: a review of the evidence of clinical efficacy of treatment. Ann Med Surg (Lond). 2024;86(12):7248–7254. PubMed
6. Shoemaker RC, House DE. A time-series study of sick building syndrome: chronic, biotoxin-associated illness from exposure to water-damaged buildings. Neurotoxicol Teratol. 2005;27(1):29–46. PubMed
7. Hope J. A review of the mechanism of injury and treatment approaches for illness resulting from exposure to water-damaged buildings, mold, and mycotoxins. ScientificWorldJournal. 2013;2013:767482. PubMed
8. Redlich CA, Sparer J, Cullen MR. Sick-building syndrome. Lancet. 1997;349(9057):1013–1016. PubMed
9. Vesper S, McKinstry C, Haugland R, et al. Development of an Environmental Relative Moldiness index for US homes. J Occup Environ Med. 2007;49(8):829–833. PubMed
10. Reponen T, Vesper S, Levin L, et al. High environmental relative moldiness index during infancy as a predictor of asthma at 7 years of age. Ann Allergy Asthma Immunol. 2011;107(2):120–126. PubMed
11. US EPA Office of Inspector General. Public may be making indoor mold cleanup decisions based on EPA tool developed only for research applications. Report No. 13-P-0356. 22 August 2013. EPA OIG (PDF)
12. Shoemaker RC. HERTSMI-2 scoring system. Surviving Mold. survivingmold.com
13. Hurraß J, Nowak D, Heinzow B, Joest M, Stemler J, Wiesmüller GA. Indoor mold—important considerations for medical advice to patients. Dtsch Arztebl Int. 2024;121(8):265–271. PubMed