Abstract: In the last decade pollution has increased at quite a tremendous rate. People are subjected to air pollutants both within and outside spaces depending on the actions of individuals. It is significant to measure the exposure levels of different pollutant gases, especially for the well being sensitive or susceptible individuals such as children, aged people and persistently ill people. To avoid such adverse imbalances in the nature, an air quality monitoring system is utmost important. Recent enhancement in technology have made it conceivable to deploy cost-effective wireless sensor nodes for environmental monitoring, indoor climate control, scrutiny, structural monitoring, gathering sensing information in unreceptive locations and ambient air monitoring.
We propose an online pollutants concentration monitoring system centered on the technologies of sensor networks. We will attempts to develop an e’ective solution for air pollution monitoring using WSN that is featured by its low-cost, renewable power source, simple to set up, without excessive maintenance etc., and it can achieve assortment of various regional low-cost unmanned continuous monitoring. This system helps us to monitor various air constituents eliminating need to visit distant sites for data collection. The data is collected to a central server and displayed automatically to a formed data base online.
Keywords ‘sensor, pollution, monitor, AQI, WSN
The dreadful conditions environmental of air are a’ecting the healthiness of more than 120 million people globally. In India the growing commercial progress and a rapidly mounting population from 300 million people to more than one billion people today is laying a stress on the environment, economical framework, and country’s natural resources. India is among the world’s worst troupes when it comes to the overall environment management. Environmental deprivation costs India about 80 billion dollar per year that is nearly 6 per cent of gross domestic product, stated on July 17th, 2013 in a report bid by the country’s environment ministry. Additional inspections show that India has the world’s nastiest air pollution, and has 13 most polluted cities out of the 20 among big world economies.
. Monitoring Air Quality is essential for State & Central authorities like air pollution regulatory body, MNC’s as well as major Public and Private industries to comprehend and take suitable steps to prevent air pollution and consider emission sources, in order to preserve health and help to the round against the greenhouse effect. An air pollution measurement system that is sufficient in terms of spatial and pollutant analysis, and is relatively low-priced and autonomous is the priority. Recent advances in information and communication technologies have resulted in the development of more e’cient, low cost and multifunctional sensors.
These micro sensors can be deployed in WSN to monitor and collect air environmental parameters . The collected information is afterward wirelessly transmitted to data server where it is accumulated and analyzed. In the India, all main cities have networks of observing stations providing real time measurements of the most important pollutants. However, the number of these posts is usually very limited. Furthermore, currently the data of the di’erent pollutants measured at the di’erent stations in the city are accumulated to a single number, the air quality index (AQI) that is issued daily on site.
II. LITERATURE REVIEW
One of the ideas behind these systems is that if exploited, they would allow ordinary people to be more upbeat when it comes to air pollution and associated health issues. Users could avoid areas where the levels are dangerously high. In the last decades there have been various pollution monitoring system that have been used for pollution measurement and monitoring.
A. Indoor Air Quality Monitoring
One of the most important health concerns is indoor air quality (IAQ). Driven by rising energy costs, structures are progressively erected or renovated to be air restricted. In consequence the air quality levels in such buildings are degraded. A wireless sensor network for monitoring IAQ has been developed in buildings. When measured pollutant levels are higher than suitable, the network will alarm indoor tenants, prompt initiation of the building’s climate control equipment which exhaust polluted air, and bring in fresh air from outdoor .
B. Mobile Air Quality Monitoring Network:
At ISIS the Networked Embedded Systems Lab produced the Mobile Air Quality Monitoring Network (MAQUMON) that entails of a number of car mounted sensor nodes determining di’erent pollutants in the environment. The data points are labelled with location and an on-board GPS. Intermittently, the measurements are uploaded to a server, processed and then issued on the Microsoft Sensor Map portal .
C. Real time Air Pollution Monitoring:
Commercially available electrochemical and resistive heating type sensors were used to sense the gases like CO2, O2, CO and NO2. Proper calibration technologies were used to calibrate these sensors, which are then fused to wireless sensor nodes. Zig bee based WSN with multi-hop data aggregation algorithm was employed to extend the range of monitoring region .
D. GPRS-Sensors Array:
GPRS-Sensors Array for air pollution monitoring has been designed, and tested. This system integrates a single-chip microcontroller, several air pollution sensors, GPRS-Modem, and a general positioning systems (GPS) module. The incorporated part can be positioned on the top of any moving device such as a moving vehicle. The microcontroller generates a frame comprising of the pollutant level from the sensors array and the location that is conveyed from the GPS module. The pollutants frame is then uploaded to the General Packet Radio Service Modem (GPRS-Modem) and transmitted to the Pollution-Server via the public mobile network .
E. Other systems:
Fourier transforms infrared (FTIR) devices, and mass spectrometers and gas chromatographs, are some of the existing devices for air pollution monitoring are. These systems give accurate and selective gas readings. However high price, large size & maintenance cost has made them unfavorable for monitoring applications on large scale. One of the large scale sensor networks for monitoring and forecasting is Environment Observation and Forecasting System (EOFS), but the size of the system and initial charge is too great. Air pollution monitoring system based on gas sensor network with control action and adaptive sampling rates also cannot be deployed due to high budget .
III. PROPOSED SYSTEM
Thus we have targeted to form a system that is inexpensive, not only to manufacture but to operate and maintain as well. The system organization costs are intended to be minimal with the minimization of restraint such as space and external power supply requirements. The proposed system should overcome the limits of singular static monitoring sites by attaining efficient high resolution, air pollution recognition. Henceforth, our objective is to develop device able to monitor certain atmospheric components and transfer the data continuously for the display ,to determine status and trends of ambient air quality and sharing certain details with agencies like Town and Country Planning Department,
Thus we propose a real-time air quality monitoring system with wireless sensor networks which possess following feature:
‘ Compact and portable.
‘ Cost e’ective and e’cient.
‘ Continuous online monitoring from remote location.
‘ Uses solar power.
‘ Consist of o’-the-shelf devices, components, and standards.
‘ Can easily adapt to take in di’erent kinds of sensors.
‘ Precise and continuous real-time data collection.
A. Proposed system methodology
Based on technologies of micro-sensors, GPRS, to meet the need of monitoring of air Pollutants, we developed a remote online monitoring system. The system mainly entails of monitoring equipment, data server and the clients, as shown in Figure 1. The design of monitoring equipment is the core task of the whole system. The equipment can be deployed in most polluted monitoring region. It can collect pollution gas concentration through sensors. GPRS network will send the assembled data to the data server, and then immediately data query, analysis and monitoring can be accomplished on various patrons.
Figure 1 System structure of Pollution monitoring system
IV. HARDWARE DESIGN
The monitoring circuit consists of a microcontroller, air environment sensors array, power supply, solar panels, liquid crystal display (LCD) module, and GSM module as shown in ‘g 2. The sensors array is used to collect data (CO and NOx). The CPU displays them on the LCD module in real-time. Afterwards, the GSM module continuously wirelessly transfers the accumulated information to the data server.
In this work, we are using the AVR microcontroller of Atmega32 for some reasons. The Atmel AVR Atmega32 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. It usually execute instructions in a single clock cycle thus allowing us to improve power consumption versus processing speed.This microcontroller type has many facility, fast instruction process and reinforced by Code Vision AVR Evaluation software for simulation and compiler. In addition, the Microcontroller of ATMEGA has special feature, like analog to digital converter. This feature is very important for our system.
Figure 2: Hardware infrastructure diagram of Pollutant monitoring system
B. Sensors Chamber:
Air environmental information acquisition sensors array includes: CO sensor and NO2 sensor. These sensors, respectively, provide real-time collection of air data to the central processing unit. Each sensor is described as following.
‘ Carbon Monoxide (MQ-7) Sensor: It has a detection range of 20 to 2,000 ppm; provide us with brilliant long life, performance with constant sensing characteristics, Response Time is less than 150sec.
‘ Nitrous oxide (MQ-135) Sensor: It is used in AQI measurement for buildings or o’ces, it is appropriate for sensing of NOx and other gases. It possess following feature: detection range of 10-100 ppm, Fast response, long life and Simple drive circuit.
The sensors used are semiconductor sensor which measure the resistance change proportional to the gas concentration that is absorbed on the metal surface of a semi-conductor. These can be used for a measurement of wide range of gases. These perform well than the catalytic type in the detection of flammable gases at low concentrations.They generally require 5V input and output an analog voltage making them super easy to use.
C. Wireless capability
We maintain wireless connectivity through a GSM modem. Any GSM network operator SIM card can be accepted by this modem. Benefit of using this modem is its RS-232 port to connect and develop embedded applications with baud rate of 9600 mbps. In GPRS mode it is used to connect to internet and for many applications like data recording and control. In this mode it also connects to any remote FTP server and upload ‘les for data charting. Thus transfer of collected data is via GPRS wireless transmission module-SIM900A. It is a small chip, compact, have high reliability and low power consumption. Microcontroller uses RS-232 to connect to GPRS wireless transmission module.
D. Power supply:
Various sensor in arrays, GPRS wireless transmission module, microcontroller and LCD display requires 5 V& 12 V for their operation. Since all these components are operating continuously for real time monitoring of pollutant gases using external battery are not su’cient. Thus to make the system stand-alone solar panels has been integrated. The charging regulator is added to supervise the battery voltage and control the charging intervals.
E. LCD Display
In our system we are using a 16×2 LCD to display gas concentration on remote location. The gas concentrations are displayed on LCD.
V. SYSTEM ANALYSIS
A. Firmware flow
Firmware process comprises two main fragments, real-time data collection and wireless transmission using GSM module. First, the sensors array collect gas concentration, through GPRS wireless trans- mission module, continuous wireless transmission is conducted as shown in Figure 3.
Figure 3 Firmware ‘ow of remote real-time pollution monitoring equipment
B. Simulation Performance
In this section we have simulated our model in ISIS professional 7.8 to ensure correct functionality of our system. Here we have developed an approximate model of our system consisting of microcontroller Atmega 32, a temperature sensor LM 35, LCD display and virtual terminal. A proper TCP/IP connection is established virtually and temperature is displayed on LCD screen as shown in ‘gure 4.
Figure 4 Simulation Result
Remote real-time monitoring equipment for measuring pollutant gases is successfully established which can realize real-time display and transmit the gas concentrations wirelessly. With compact size, the weight of monitoring equipment is 287 g. It can be easily placed in various experimental atmospheres as it is simple and movable. The implementation of circuit board is as shown in Figure 5.
Figure 5 Implementation of basic circuit
The circuit was tested sucessfully and it showed the result as shown below in Figure 6.
Figure 6 Photograph of test results
We have tested the circuit under room conditions and produced some smoke for testing and its response in adverse environment condition is to be tested yet.
Thus here we have proposed and successfully realized a cost e’ective method of measuring air pollution constituents in an urban location. Temperature and gas concentration in ppm are displayed on LCD screen and a proper TCP/IP connection is established on virtual terminal as shown earlier. We have also measured and compared gas concentration as shown in table I below:
Table I: Comparative analysis of pollution
Sr. No. Date MPCB data during Nov.13 (Avg.) System readings
CO ??g/m3 NOx ??g/m3 CO ??g/m3 NOx ??g/m3
1 21/2/2014 3.0 27 2.9 28.8
2 22/2/2014 2.7 27 2.65 19.7
3 23/2/2014 2.6 27 2.56 24.35
From the above gas concentration it is concluded that AQI was found to be good.
Thus here we have proposed a cost e’ective system for measuring air pollution concentrations in an urban setting. We have limited our project cost up to 20k. The project is principally economical, compacted, energy saver and holds the ability to be installed in large numbers to overcome the limitations of traditional environment monitoring systems. We have designed a system which aims at increasing attentiveness to the average citizen by displaying pollution level among them.
In near future, we plan to develop a successful online WSN air quality monitoring system with better dependability. We are also going to examine the practicability, reliability and precision of the project when mounted in an urban setting. For researchers in the ‘eld of environmental, our model could assist as a basis for a low cost air pollution monitoring system, which can be expanded with many new sensors, assessment algorithms and methodologies.
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