Skin may become dry or scaly. Asthma symptoms may become worse. Of particular concern are those particulates less than 10 millions of an inch in diameter. Respirable particulates may cause eye, nose, and throat irritations, as well as respiratory infections and bronchitis. The most likely sources are a fireplace, wood stove, and unvented gas or kerosene heater.
Nitric oxide causes similar symptoms.
At high concentrations, NO can also cause headaches, drowsiness, and nausea similar to the effects of carbon monoxide. The most likely sources of a high build-up of NOx are furnaces and appliances fueled by natural gas. Some respirable particles contain polycyclic aromatic hydrocarbons which may cause cancer following long-term exposure. Like nitrogen dioxide, sulfur dioxide has a pungent odor at high concentrations and irritates the upper respiratory tract. If these symptoms occur in a room where you are using a kerosene heater, you probably need additional ventilation.