Stable ventilation: how to measure air quality

Why air quality matters so much

A horse inhales an average of 60 to 80 litres of air per minute. During exertion, this rises to 1,800 litres per minute. That makes the airways vulnerable: ammonia from urine and manure irritates the mucous membranes, fine dust from hay and bedding causes inflammation, and mould spores can lead to COPD or RAO (recurrent airway obstruction). Stable air that feels 'fine' to you can already be harmful to your horse — the threshold for ammonia in horses is 10 ppm, while humans only experience discomfort at 25 ppm.

The four measurement values that matter

Focus on these four parameters for a complete picture of stable air quality:

• Ammonia (NH₃): maximum norm 10 ppm; higher values damage the lung epithelium
• Relative humidity: ideally 60–80%; below 50% the mucous membranes dry out, above 85% promotes mould growth
• CO₂: maximum 3,000 ppm; indicates whether sufficient fresh air is entering
• Fine dust (PM2.5 and PM10): the lower the better; ventilate before and immediately after feeding hay
• Temperature: aim for 5–15 °C; large fluctuations are just as harmful as extreme cold

Affordable measuring equipment for stables

You don't need to hire an expensive laboratory. There are three practical options:

• Digital multi-sensor (€80–€200): measures CO₂, humidity, and temperature simultaneously; brands such as Aranet4 or CO2Meter are suitable for stable use
• Ammonia sensor (€150–€400): specifically for NH₃; measures continuously and triggers an alarm above a set threshold
• Dust meter (€100–€300): optical particle counter; useful for seeing the peak immediately after hay feeding
• Periodic professional measurement: a specialist company measures all values on a one-off basis for €200–€500 and provides a report

How to measure correctly in the stable

Measurement position and timing determine whether you get reliable data. Hang sensors at the horse's breathing height: approximately 120–140 cm above the stable floor, not directly next to a window or air vent. Measure at three moments: early in the morning before mucking out, in the middle of the day with doors closed, and in the evening after feeding. Also note the outdoor weather — in low wind and high outdoor humidity, values inside the stable are often at their highest. Record measurements in the horse profile in EquiSight so you can track trends over weeks or months.

Improving ventilation: practical measures

• Open ridge or roof ventilators: the most effective passive ventilation; ensures warm, moist air flows upward and out
• Inlets low, outlets high: ideal air circulation runs from bottom to top; side windows only as a supplement
• Minimum ventilation standard: 50–80 m³ of fresh air per hour per 100 kg of horse; calculate this for your stable size
• Avoid draughts at floor level: air may move, but the horse must not receive a direct cold airflow on its back
• Add a dehumidifier or fan: in older stables without a ridge, a ceiling fan on a low setting helps mix the air

Bedding and feed: direct impact on air quality

Ventilation partly solves poor stable air, but tackling the source works better. Use bedding with low ammonia emissions, such as chopped straw, wood pellets, or flax — these bind ammonia better than long straw. Replace the bedding completely at least twice a week. Lightly dampen dry hay just before feeding, or consider haylage or silage. Do not store roughage in the stable but in a separate, dry area. Small adjustments to bedding and feeding can already reduce NH₃ levels by 30–50% within two weeks.

Using EquiSight to track health patterns

Link your measurement results to health notes in the horse profile in EquiSight. If you record when your horse coughs or has a runny nose and compare that to the ammonia values from that week, you'll quickly spot connections. EquiCoach helps you interpret the data and provides concrete suggestions — for example, whether a pattern found points to a ventilation problem, an allergy to a particular bedding brand, or something else. Use the calendar to schedule periodic measurements so that it doesn't stop at just one reading.