Below 53ppb
High levels of Nitrogen Dioxide indoors is the result of outdoor NO2 entering your indoor environment as well as combustion sources inside the home / workplace. According to a study published in the Environmental Research journal, short-term exposure can irritate airways while long-term exposure can lead to chronic illness and respiratory infections with viruses7. Asthmatics may also experience longer symptomatic periods and increased medication use for children.
Examples of sources of nitrogen dioxide: Automobiles from attached garage or near a busy street, appliances with defective installations, gas stoves, kerosene heaters, chimneys, etc.