Overview
Ozone is a gas composed of three atoms of oxygen (O3). Ozone occurs both in the Earth's upper atmosphere and at ground level. Ozone can be good or bad, depending on where it is found:
- Good Ozone occurs naturally in the stratosphere. It is found 6 to 30 miles (12-47 km) above the Earth's surface where it forms a protective ozone layer that shields us from the sun's harmful ultraviolet rays.
- Bad Ozone is found in the troposphere. Near ground level, ozone is formed when pollutants such as nitrogen dioxide (NO2) and volatile organic compounds (VOC) emitted by cars, power plants, refineries, and other sources react chemically in the presence of sunlight. Ozone at ground level is a harmful air pollutant and is mainly due to human activities. Since ozone is formed in the sun, geographical areas that are sunny usually have worse cases of tropospheric ozone, where levels are highest in the afternoons and early evenings as it accumulates during the day. Areas that have inversion layers (cities between mountains or coastal areas) and large populations are likely to have the worst ozone issues.
How ozone can impact human health
Ozone can irritate your respiratory system, reduce lung function and aggravate asthma. It can cause coughing, and irritation in your throat, and/or an uncomfortable sensation in your chest. It can make it more difficult for you to breathe as deeply and vigorously as you normally would. More people with asthma have attacks that require a doctor's attention or the use of additional medication.
Ozone can inflame and damage cells that line your lungs, cause permanent lung damage, and aggravate chronic lung diseases. Within a few days, the damaged cells are replaced, and the old cells are shed-much in the way your skin peels after sunburn, however, repeated short-term ozone damage, especially to children's developing lungs, may lead to reduced lung function in adulthood. Chronic lung diseases such as emphysema and bronchitis area aggravated and reduce the immune system's ability to fight off bacterial infections in the respiratory system.
Air Quality Index
The Air Quality Index, or AQI, is a scale used to report actual levels of ozone and other common pollutants in the air. The higher the AQI value, the greater the health concern. As shown in the table below, the AQI scale has been divided into categories that correspond to different levels of health concern.
- Read Ch 13 in the text and the introduction to tropospheric ozone in the lab assignment below and watch the instructor video if available.
- Check the Grading Rubric at the bottom of the page
- Download the
- Use your textbook (Ch13 – The Atmosphere, Air Quality, and Pollution Control) and the videos below to answer specific text and video questions (Use submission template):
- Utilize https://www.epa.gov/outdoor-air-quality-data/air-data-tile-plot (Links to an external site.) to research and assess the seasonal scope of ozone alert days within a region of the US
- Visit the Environmental Protection Agency government website: Air Quality Data (Links to an external site.)(https://www.epa.gov/outdoor-air-quality-data/air-d... (Links to an external site.))- this site provides daily air quality index information for specific locations
- Under pollutant, use the drop down to select “Ozone”
- Under Year, use the drop down to select 1. 1981, 2. 2019
- Under Geographic area, use the drop down to find either Los Angeles, CA for City or CA – Los Angeles for county
- Click “Plot Data”
- Use the count of the total number of Air Quality Index (AQI) days in the legend below the graph to fill in the data table on the Submission template (i.e. days that show Green (Good), Yellow (Moderate), Orange (unhealthy for sensitive groups), Red (Unhealthy), Purple (Very Unhealthy), and Hazardous (Brown) for 1981 and 2019. See example below.
- Select a different city/region in the US of your choice and repeat the above procedure for a year at the beginning of that city’s/region’s data record and the year 2019. Be sure to write the city/region you choose in the table below.
- Answer questions about the seasonality and scope of air quality in Los Angeles and the specific area you selected. (For example, notice the seasonal timing of all the poor air quality in Bakersfield below which reflects photochemical processes and greater sunlight during the summer)
- Complete the data table and analysis of air quality for your selected city and describe the possible human links to air pollution (Use submission template)
- Answer questions regarding the legacy and future of air pollution in the US and in developing countries (Use submission template).