According to data from the Central Pollution Control Board (CPCB), ground-level ozone (O3) has started to emerge as Delhi’s lead pollutant during the day regularly, particularly after good spells of rain.
- The presence of ozone prevented Delhi’s air from touching the “good” cate- gory during this period.
Ground-level ozone
- Ozone can be “good” or “bad” for health and the environment depending on where it’s found in the atmosphere.
- Stratospheric ozone is “good” because it protects living things from ultraviolet radiation from the sun. Ground-level ozone is “bad” because it can trigger a variety of health problems.
- Good ozone occurs naturally in the upper atmosphere, where it forms a protective layer that shields us from the sun’s harmful ultraviolet rays.
- Tropospheric, or ground level ozone is a harmful air pollutant, because of its effects on people and the environment, and it is the main ingredient in “smog.”
- Ground level ozone, is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC).
- This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight.
- Ozone is most likely to reach unhealthy levels on hot sunny days in urban environments, but can still reach high levels during colder months.
- Ozone can also be transported long distances by wind, so even rural areas can experience high ozone levels.
