IAQ – indoor air quality in horse stables is important

We do not have to make a drawing, but horses are indeed living and even precious animals. That is why you want to make sure that in the summer, but especially in winter, the horses are in high-quality, well-ventilated and clean stables.

Recently we were contacted by a couple from East Flanders who in their turn were warned by the vet that they have to contact air quality specialists.


The horses regularly struggled with breathing problems and emphysema. When a horse has chronic airway problems, this can lead to serious problems such as damage to the alveoli and the production of stiff lung tissue.

Lung emphysema

The alveoli suck with air while breathing, but the outflow is complicated by the mucus, muscle constriction and scar formation that block the lung tubes. So there is more air coming in than there is flowing out again. Because there is more air in the vesicle every breath than goes out, the alveoli can become overfilled and even burst. This is irreparable. The cracked alveoli ensure that the lung can no longer function optimally.


Moisture causes a worsening of the condition and less endurance. In this way the horse can breathe harder during exertion and it gets rather stuffy. In case of sudden or intense effort and at a later stage also at rest, the horse can breathe jerkily. The damage that fits with emphysema is irreparable and a horse can be permanently distressed by these problems. It is therefore of great importance that a veterinary surgeon is consulted at an early stage for airway problems and this case is airvisor for constant monitoring of air quality.

Today it is cold, wet and foggy, bad conditions for horse stables.

When we look at the “air-quality platform” and we do this over a period of 24 hours, different things quickly become clear:

VOCs or volatile organic compounds

volatiele organische stoffen

Volatile organic compounds (VOCs) are organic chemicals with a high vapor pressure at normal room temperature. Their high vapor pressure is due to a low boiling point, causing large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and penetrate the surrounding air, a property known as volatility. Harmful gases such as ammonia, hydrogen sulphide, methane and carbon dioxide are caused by microbial conversions in manure and urine. These voc’s are extremely high, in a human the total voc’s are between 0 and 0.7 ppm (parts per million) Here we see that the voc’s sometimes go to more than 3.5 ppm which is also very harmful for a horse.

We have to mention that this happened during the night, the absolute peak was at 4.30 am at night because the windows of the barn are closed for freezing temperatures.

Fine Dust, PM10 (μg / m³)

fijnstof in paardestallen

This is inevitable in a stable, but you have to keep particulate matter under control. This fine dust is best under 40μg / m³ but here we see that PM10 average a value of 55μg / m³ which is not bad but must be kept in mind. The particle levels vary depending on numerous factors, such as ventilation, management and activity in the barn. We see that there is a similar trend for PM2.5 and PM1, albeit that they are in lower values. Ideally, PM2.5 and PM1 are below 10μg / m³, but here too, PM2.5 averages 42μg / m³ and PM1 averages 26μg / m³ which is too high. Fine dust causes inflammation of the airways. There will always be peaks when feeding what is normal.

Relative humidity %RH

relatieve vochtigheid

For a horse, the relative humidity should be between 50% and 70%. We have already discussed the issue of dampness and its consequences. We all know that too little or too much fluid is a big problem for humans and animals. If we look at the graph we see that of course at night the humidity is the highest because the windows in this barn are closed to the cold and there is no other way of ventilation. After a good cold night you can also see the water drops on the windows on the inside.

We are now at an average of 75.4% humidity while we report that it should be under 70%. The relative humidity in a person is a bit different than with a horse. This is therefore much too high and here too the big culprit is a bad or even no illumination.

The temperature here is not really a problem, with windows closed it is almost 10 ° C and with door and windows open still above 0 ° C so sufficient ventilation, given the temperature is good for the time being. A temperature between 10 ° C and 25 ° C is ideal for horses.

CO2 (carbon dioxide)


This is much too high, which again is due to bad ventilation. We see a falling peak at 7.15h and 9.15h when someone is likely to enter the barn and at 9:30 am the windows are probably opened. Everything under 800PPM is good but again an average of 1445ppm because horses exhale naturally and this air is not optimally refreshed. In itself, too high CO2 is not very bad. The carbon dioxide content may indicate a high level of other harmful air pollutants such as volatile organic compounds (VOCs) that we have already indicated and these are harmful.

All these remarks we formulate after 24 hours air quality measurement and presumably is the biggest cause of respiratory problems in the horses, the poor ventilation. Especially for horse stables there are numerous examples of how a stable is optimally ventilated.

After another week, samples are taken for the concentration of ammonia and mainly samples for the detection of fungi, spores and bacteria.

Tips for airway problems with horses:

  • Much grazing to reduce dusty barn hours
  • Avoid draft (straight on the horse)
  • Less dusty stable floor (straw) by switching to flax or wood chips
  • Clean stable without sharp ammonia air
  • Pre-moisten the hay so that it is less dusty
  • Regular grafting against Influenza

Contact us if you want to know more about the air quality where you are.

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