Chapter 1: Introduction
Air pollution has always accompanied civilizations and dates back to prehistoric times when man first created the first fires. Environmental pollution was a direct result of the industrial revolution, where the industrial revolution era caused the emergence of great factories and increased consumption of immense quantities of coal and other fossil fuels .
Carbon monoxide (CO) is a common industrial pollutant resulting from the incomplete burning of natural gas and any other material containing carbon such as gasoline, kerosene, oil, propane, coal, or wood. Forges, blast furnaces and coke ovens produce CO, but one of the most common sources of exposure in the workplace is the internal combustion engine. Carbon monoxide is harmful when breathed because it displaces oxygen in the blood and deprives the heart, brain, and other vital organs of oxygen. Large amounts of CO can overcome you in minutes without warning—causing you to lose consciousness and suffocate. Besides tightness across the chest, initial symptoms of CO poisoning may include headache, fatigue, dizziness, drowsiness, or nausea . Sudden chest pain may occur in people with angina. During prolonged or high exposures, symptoms may worsen and include vomiting, confusion, and collapse in addition to loss of consciousness and muscle weakness . Symptoms vary widely from person to person. CO poisoning may occur sooner in those most susceptible: young children, elderly people, people with lung or heart disease, people at high altitudes, or those who already have elevated CO blood levels, such as smokers. Also, CO poisoning poses a special risk to feotuses.
Real time monitoring and data acquisition have important role in industry and also in everyday life. For example, in literature can be found description of systems used in pollutant detection , and greenhouses air quality monitoring .
In last few decades attention is especially focused on environment (air, soil and water) pollutant monitoring. These systems require sensing elements with high accuracy, selectivity and sensitivity. Data acquisition in these systems is also very important and systems have to be able to store data in long time period for analysis and decision making.
The emergence and development of the Reduced Instruction Set Computer (RISC) chips and digital sensors has made function of monitoring system more and more powerful. RISC processors are designed to perform a smaller number of types of computer instructions so that they can operate at a higher speed, performing more millions of instructions per second (MIPS) . By stripping out unneeded instructions and optimizing pathways, RISC controllers provide outstanding performance at a fraction of the power demand of complex instruction set computing (CISC) devices. In this research, an environment pollutant monitoring system used in the vicinity of industrial plants and in the general atmosphere based on the RISC architecture and digital sensors is designed. The system measures environment data (gaseous pollutants) concentration, which is transferred and displayed on the LCD monitor in real time, achieving the real-time monitoring of gaseous pollutant level; analyses the data collected over a period of time to obtain the additive effects and exposure levels; compares periodic exposure levels with employees’ past medical history and periodically suggest those that might be at high risk, thereby enhances employees’ health surveillance. The system will also triggers CO alarms and oxygen gas at exposures below those at which symptoms occur, while occupants still have time to take action to protect themselves. For healthy adults, CO becomes toxic when it reaches a level higher than 40.075mg/m3 or 35 ppm (parts per million) with continuous exposure over an eight hour period . When the level of CO becomes higher than that, a person will suffer from symptoms of exposure. Mild exposure over 2-3 hours (a CO level between 35 ppm and 200 ppm) will produce flu-like symptoms such as headaches, sore eyes and a runny nose. Medium exposure (a CO level between 200 ppm to 800 ppm) will produce dizziness, drowsiness and vomiting in as little as 1 hour. This level of exposure is deemed to be life threatening once three hours has passed. Extreme exposure (a CO level of 800 ppm and higher) will result in unconsciousness, brain damage and death in as little as a few minutes. United States’ Occupational Safety and Health Administration (OSHA) guidelines state that the maximum exposure over an eight hour time period is 35 ppm. Measurement to determine employee ceiling exposure will be taken during periods of maximum expected airborne concentration of carbon monoxide. Air samples are taken in the employees’ breathing zone (air that would nearly represent the one inhaled by the employee).
1.1 Statement of Problem
Exposure to gaseous pollutants in the workplace is common. This can occur through inhalation, absorption through the skin or ingestion. Most exposure occurs through the inhalation of vapours, dusts, fumes or gases. For some substances, absorption through the skin may also be a significant source of exposure. These substances or mixtures may cause immediate acute health effects or it may be decades before the effects on the body become evident thereby reducing employee productivity. However, several environmental data monitoring systems have been developed to help monitor gaseous pollutant concentration in the workplace. Besides, these systems have the following challenges:
- Several of the environmental monitoring systems do not provide reliable data monitoring and subsequently cannot respond to sensitive emergency situations in industrial vicinities.
- Data acquired by these systems are not being utilized for decision making especially in maintaining efficient employee health surveillance.
1.2 Aims and Objectives of Study
The aim of the study is to design an environmental data monitoring system using a microcontroller for industrial air pollution concentration measurement. The developed should be able to:
- Provide reliable gaseous pollutant monitoring which can respond to sensitive emergency situations in industrial vicinities.
- Use the data acquired from the monitoring system for decision making, especially in maintaining effective employee health surveillance.
1.3 Significance of the Study
- The system provides more precise, time sensitive and responsive environmental pollutant monitoring in industrial facilities. This was achieved by using sensitive digital gas sensors and digital microcontrollers. Pollutant monitoring is made easy, simple and reliable.
- Data acquired and analyzed would help to perform employee medical surveillance to ensure improved Health and Safety (H&S) of workers. Organizations may not need worry about employees being over exposed to these industrial pollutants. This is achieved by adding employee health information to the system and periodically querying the system for employees that could possibly be at risk.