Aeroqual their ozone monitors are designed with “active sampling” to maximize air sampling at the sensor (to minimize ozone losses). Most expensive, analytical instruments also employ active sampling (e.g. UV photometry).

Products without “active sampling” (electrochemical and conventional HMOS products) will normally under-read ozone concentrations below 200 parts per billion and struggle with sensitivity and accuracy, particularly in low air flow.

“Active sampling” requires air to be blown or pumped to the sensor under precise flow conditions. Aeroqual fan based monitors are designed to be held at right angles to any direct stream being measured. Avoid forcing pressurized air into active sampling monitors.