Sick building syndrome and air conditioning: what office studies found about headaches, dryness and tiredness

Sick building syndrome is the name for a set of symptoms that people report in certain buildings, usually offices: headache, tiredness, dry or irritated eyes and throat. If you have ever thought "air conditioning makes me sick" by mid-afternoon, this is the research that comes closest to your question. Six sources are used here: four papers on ventilation type and health, and two reviews of indoor temperature and humidity.

It is informational material, not medical advice. Symptoms that keep returning are a question for a doctor, not for a thermostat.

One limit up front. The popular names for this ("AC illness" and similar) do not appear in these papers. The researchers measured symptoms in people working in buildings with different ventilation, and that is what this article reports.

Sick building syndrome symptoms: air conditioning, headache and lethargy

The oldest source is a 1990 reanalysis of six studies, five from the United Kingdom and one from Denmark, with unpublished data supplied by the original authors. Compared with naturally ventilated buildings, air-conditioned ones were consistently linked to a higher prevalence of three groups of symptoms. Work-related headache had odds ratios of 1.3 to 3.1, lethargy 1.4 to 5.1, and symptoms of the mucous membranes and upper airways 1.3 to 4.8. Humidification was not a necessary condition for the pattern. Mechanical ventilation without air conditioning was not linked to more symptoms (Mendell & Smith, 1990).

An odds ratio above 1 means the symptom was reported more often in one type of building than in the other. It says nothing by itself about why.

Dry skin and airway symptoms: the California buildings

The California Healthy Building Study looked at 12 public office buildings in Northern California in the summer of 1990: three naturally ventilated, three mechanically ventilated without air conditioning, and six air-conditioned. The buildings were chosen without regard to complaints, and 880 employees filled in questionnaires. Most symptoms were reported more often with both mechanical ventilation and air conditioning than with natural ventilation.

The highest odds ratios were for dry or itchy skin: 6.0 in mechanically ventilated buildings (confidence interval 1.6 to 22) and 6.0 in air-conditioned ones (1.7 to 21). Lower respiratory symptoms came next in air-conditioned buildings, at 4.0 (1.1 to 15). Those intervals are wide, so the size of the effect is uncertain even where the direction is clear. The authors judged that bias from participants' own reporting was small (Mendell et al., 1996).

What a later review concluded

A 2002 review by Seppänen and Fisk pulled this literature together. Compared with natural ventilation, air conditioning, with or without humidification, was consistently associated with a statistically significant increase in one or more SBS symptoms, roughly 30% to 200%. The link to plain mechanical ventilation was less consistent.

The authors add two points. The associations appear far more often than chance would produce, and they are unlikely to be explained by a range of personal, job and building confounders. And the possible contribution of design, installation, operation or maintenance problems in the ventilation and air-conditioning systems is named, including pollutant emissions from the systems themselves. Other causes remain unclear, and there was not enough data to say what role humidification and recirculation play (Seppänen & Fisk, 2002).

So the research does not say that cool air as such is the problem. It says that buildings with air conditioning tend to come with more of these symptoms, and that the system's condition may matter.

Sick days and ear, nose and throat visits

One study followed health care use rather than symptoms. It tracked 920 working women aged 49 to 65 from the French SU.VI.MAX cohort through 1999, and compared workplaces with heating, ventilation and air-conditioning systems with those that had natural ventilation. After adjustment, the odds ratio was 2.33 (1.35 to 4.04) for a visit to an ear, nose and throat doctor and 1.70 (1.13 to 2.58) for sick leave (Preziosi et al., 2004).

The design limits what can be read from this. Only women aged 49 to 65, one year, one country. And the study does not say which illnesses people had. It is not evidence that air conditioning gave anyone a cold.

Office air conditioning temperature: what the reviews give

Two reviews by Wolkoff cover the physical side. The 2021 review, with Azuma and Carrer, describes the dose-response curve for temperature as concave: low temperature raises the risk of cardiovascular and respiratory disease, and higher temperature raises the risk of acute non-specific symptoms such as dry eyes and respiratory symptoms. Cognitive and work performance is best between 22 and 24 °C in regions with a temperate or cold climate. That is a performance benchmark from a review, not a tested thermostat setting, and no paper here tested which setting is best for health (Wolkoff, Azuma & Carrer, 2021).

The same review says personal control over ventilation affects satisfaction with thermal comfort, and that ventilation can itself be a source of pollutants, allergens and pathogens.

Dry air in the office and a dry throat

Low indoor humidity dries the eyes and airways, and the clearance of mucus by the airway lining works less well. Humidification eased dryness of the eyes and airways, tiredness symptoms and "dry air" complaints, according to the 2021 review.

A 2018 overview adds a detail about perception. Eye and upper airway irritation are usually among the top two symptoms in offices, together with a feeling of "dry air". People have no sense organ for humidity, so "dry air" can reflect smell and dustiness as well as the drying effect of low humidity (Wolkoff, 2018). A dry throat at your desk does not tell you which of those it is.

What about a cold or a sore throat?

Readers often want to know whether office air conditioning gives you a cold. None of the six sources tested that. The respiratory findings above are symptoms of the mucous membranes and airways, which is a different thing from an infection. Whether being cold can lead to a cold is a separate question, covered in does getting cold give you a cold. The runny nose some people notice when stepping from a warm office into cold air is in sudden temperature changes. Air conditioning at night has its own article: bedroom temperature for sleep.

What nobody knows yet

• Almost all of the data is observational and old: buildings of the 1980s and 1990s. A link is not a cause, and modern offices may differ.
• No paper here studied the jump between the street and the office.
• Nobody here tested whether air conditioning leads to a cold.
• No work tested which temperature to set, apart from the 22 to 24 °C performance benchmark from one review.
• The French cohort covers only women aged 49 to 65 and does not name the diseases behind the visits and sick leave.
• The role of humidification and recirculation remains unclear because the data are insufficient.

What you can check in your own data

MeteoHealth records outdoor weather (pressure, temperature, relative humidity, wind speed and UV index) next to your symptom entries and Apple Health data, and looks for correlations in your own history. Its fixed list has nine symptoms: headache, fatigue, drowsiness, dizziness, anxiety, irritability, nausea, joint pain and insomnia. Cough, sore throat and fever are not on it.

The app does not measure indoor air and does not know where you spent the day. It does not diagnose. So there is an honest limit: if your headache days do not line up with the outdoor weather, the app will not show a cause in the office. That is something you can only notice yourself, for example by writing down on which days you worked in the office.