1. Air Pollution as a Feedback Control Loop Andrew McCarthy

2. Introduction Air Pollution Feedback Control Purpose and Components of Feedback Examples of Feedback Components of Air Pollution Feedback Control

3. Air Pollution Feedback Control Air pollution is monitored and managed by a feedback control system

4. Air Pollution Feedback Control Economic growth has benefits, but with those benefits come risks, such as those caused by air pollution. As a result, the growth must be controlled.

5. Purpose of Feedback The primary reason for feedback control is to measure and compensate for the effect of disturbances.

6. 4 Elements of Feedback Sensor Reference Input Comparator Control Mechanism www.oz.net/~coilgun/levitation/feedbackloop.htm

7. Sensor The sensor measures the variable that we seek to control, also known as the control variable.

8. Reference Input This specifies the value the controlled variable should have.

9. Comparator Compares the sensed value with the reference value. It also specifies the direction in which the correction needs to be made.

10. Control Mechanism Takes the output of the comparator and corrects the sensed value in the direction of the reference input.

11. Practical Examples Temperature Control-No 2 nd Loop Thermostat sensor, user inputs, thermostat compares, furnace and AC control

12. Practical Examples Pitch Control of an Airplane Pitch sensor, pilot inputs, computer compares, elevator controls http://www.engin.umich.edu/group/ctm/examples/examples.html

13. Air Pollution Context It is possible, in the context of economic growth, to have two loops, one which works to reinforce growth, and the other which mitigates against further growth.

14. Air Pollution Context The second loop is not an intrinsic property of feedback control. It is possible for feedback control to contain only one loop.

15. How is pollution sensed? Monitoring agencies use EPA approved equipment. PM and lead are measured over a 24 hour period, whereas gaseous pollutants are measured hourly. Collected data is then compared to the Clean Air Act standards (NAAQS) for each pollutant. http://www.epa.gov/region08/air/monitoring/monitoring.html

16. Pollution Reference Value The EPA creates Clean Air Act standards (NAAQS) for each pollutant. http://www.epa.gov/region08/air/monitoring/monitoring.html

17. Pollution Reference Value NAAQS: Carbon Monoxide (9 ppm, 8 hour) PM10 (150ug/cubic meter, 24 hour) PM2.5 (65ug/cubic meter, 24 hour) Ozone (.08 ppm, 8 hour) Sulfur Oxides (.14 ppm, 24 hour) http://www.epa.gov/air/criteria.html

18. Air Pollution Comparator The EPA compares the data collected by monitoring sites to the Clean Air Act Standard. http://www.epa.gov/region08/air/monitoring/monitoring.html

19. Air Pollution Control Mechanism If pollution levels are above the NAAQS and present a risk, the monitoring agency in the state must develop and implement a plan to reduce the air pollution. http://www.epa.gov/region08/air/monitoring/monitoring.html

20. Conclusion Air Pollution Feedback Control Purpose and Components of Feedback Examples of Feedback Components of Air Pollution Feedback Control

21. References http://www.oz.net/~coilgun/levitation/feedbackloop.htm http://www.acfr.usyd.edu.au/teaching/3rd-year/mech3800-SystemsControl/material/lectures/block%20diagrams.pdf http://www.engin.umich.edu/group/ctm/examples/examples.html http://www.epa.gov/region08/air/monitoring/monitoring.html http://www.epa.gov/air/criteria.html