What is Air Pollution?
Two common types of air pollutants that can reach unhealthy levels and affect lung health:
Ground level ozone smog, commonly referred to as smog, is formed by a chemical reaction between volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. VOCs are organic compounds that easily become vapors or gases, such as engine exhaust. NOx gases are produced from the reaction among nitrogen and oxygen during combustion. One of the largest producers of NOx gases is vehicle engine fuel combustion.
Ozone concentrations can reach unhealthy levels when the weather is hot and sunny with little or no wind. Unlike upper atmosphere ozone, which occurs naturally and is beneficial because of its protective qualities, ground level ozone is a manmade air pollutant that can have harmful effects on both humans and the environment. Daily ozone levels are typically highest in the evening and lowest around sunrise.
Fine particulate matter, called soot, refers to tiny particles or droplets in the air (nearly invisible to the naked eye), usually a by-product of combustion, such as auto and diesel exhaust, power plant emissions or wood smoke.
Soot can reach high levels under the same weather conditions as smog. It can also occur at any time of the year when dry, calm and clear conditions can allow particle pollution to concentrate. Soot reduces visibility and causes the air to appear hazy when levels are elevated.