MACHEREY-NAGEL Ozone Test Sticks for Air Monitoring, Box of 12 — 10‑min Results, Reference Color Scale

MACHEREY-NAGEL Ozone Test Sticks (Box of 12) are single-use indicator strips that give a quick visual readout of ozone concentration in outdoor air within minutes.

These compact test sticks let you measure ambient ozone where you are — not just at distant monitoring stations. Ozone is an invisible oxidizing gas that can irritate eyes and airways; local concentrations vary with sunlight, traffic and weather. The 90736 kit contains twelve individual strips and a reference colour scale so you can assess results on-site after a ten-minute exposure under standard conditions.

How do I use these test sticks to check ozone levels?

Using the strips is straightforward: expose a single stick to open air for ten minutes and then match the resulting colour to the printed scale. Position the strip away from direct gusts of wind and secure it if needed so the exposure is consistent. The manufacturer provides calibration values for common ozone concentrations under standard pressure and temperature.

• Expose one strip in open air, sheltered from strong wind.
• Fix the strip with tape if required to prevent movement.
• Wait ten minutes before comparing to the colour chart on the container.
• Use conversion data (µg/m³ to ppm) supplied for interpretation.

What concentration ranges will the test indicate?

The colour scale is graduated into four practical ozone bands, helping you quickly distinguish low, moderate and higher levels. Results are reported in micrograms per cubic metre categories that correspond to approximate ppm values under standard conditions. Keep in mind environmental humidity and other oxidizing gases can shift apparent readings.

• < 90 µg/m³ (approx. 0.0451 ppm)
• 90–150 µg/m³ (approx. 0.0752 ppm)
• 150–210 µg/m³ (approx. 0.105 ppm)
• > 210 µg/m³ — indicates elevated ozone

What factors can affect the accuracy of the reading?

Certain conditions and chemicals can change the strip’s colour independently of ozone, and humidity influences the measurement window. Oxidizing substances such as chlorine produce similar colour changes and may cause falsely high readings. The strips are validated for relative humidity between 30% and 60%; values outside this range tend to bias results downward (low humidity) or upward (high humidity).

• Interference from other oxidants (e.g., chlorine) can mimic ozone.
• Humidity 30–60% is the validated operating range for best results.
• Readings are referenced to standard pressure (101300 Pa) and 20°C.
• Local meteorology and pollution sources will change actual exposure.

When and where should I place the strip for a representative local reading?

Choose a spot that reflects the environment you want to assess — for example a street corner, near a playground or at a workplace entrance — and avoid placing the stick in a direct draft or immediately next to combustion sources. Place the strip about head height for personal exposure checks, and out of direct precipitation. If you need repeated checks, expose fresh strips at the same location and time of day to compare trends.

• Pick locations representative of actual human exposure (head height).
• Avoid immediate proximity to exhaust pipes or strong drafts.
• Keep strips dry during exposure; protect from rain but allow air flow.
• Repeat tests at consistent times to monitor changes over days.

Who this product is for: MACHEREY-NAGEL 90736 Ozone Test Sticks suit technicians, environmental officers, facility managers, schools and concerned citizens who need an affordable, quick on-site indicator of ambient ozone. They are ideal for spot checks where fixed monitoring stations don’t reflect local microclimates, for preliminary surveys before deploying instruments, or for routine screening at outdoor venues. The strips are not a substitute for calibrated analyzers when precise numerical ozone measurements are required.