The concentration of NO2 is measured in micrograms in each cubic metre of air (μg m-3). To protect our health the UK Governments set two air quality objectives, 1. The hourly objective, which is the concentration of NO2 in the air averaged over an hour. This ensures that the exposure to high concentrations is monitored; 2. The annual objective which is the concentration of NO2 in the air averaged over a year. This is to protect us from long term exposure. The European Union (EU) has set the exposure limits of NO2 to 200 μg m-3 hourly with no more exceedances over a year and the annual limits to 40 μg m-3. NOx can be measured continuously using an instrument called chemiluminesence analyser or cumulatively using NOx diffusion tubes. Who funded the development of V-Leaf®? The development of V-Leaf is funded by the EU commision and Vitaponix. Development of V – Leaf®. Over £400,000 have been invested to date for the development and trials of V-Leaf® to demonstrate its efficacy.