Monitoring indoor air quality with Waspmote to prevent accidents and improve production processes

Monitoring indoor air quality with Waspmote to prevent accidents and improve production processes

October 27th, 2010 - Alicia Asín

Many production processes in industry, agriculture, viticulture and livestock require specific environmental conditions to be monitored at all times. Sometimes the process can generate air pollutants that can be harmful and even deadly to workers in certain concentrations. The fact of having a monitoring system with Waspmote allows to control the parameters of a production process, send alerts via GPRS and even activate mechanisms through the relay actuator included in the prototype board.


The first example of indoor air pollutants are volatile organic compounds (VOCs), which are released in the process of burning fuels such as gasoline, wood, coal or natural gas or by solvents, paints or derivatives. They are commonly used in paint thinners, aerosols or sprays and are present in food and steel industries and the manufacture and processing of cosmetics, pharmaceuticals, cleaning products, footwear, plastic, rubber, paints, varnishes, lacquers and wood.



Its concentration in air is regulated by Directive 2004/42/CE of the European Parliament, whose definition of VOC is "any organic compound with a boiling point less than or equal to 250 º at a standard pressure 101.3kPa." In the rest of the world, the legal limits of concentration of VOCs vary even between cities in the same state, as in California, USA, so it is recommended to consult on a case by case.



Besides the potential danger posed by the volatility and flammability, they are soluble (they accumulate in the human body due to its affinity to fats) and toxic, causing eye and throat irritation, headaches, sickness, fatigue, nausea and diverse allergic reactions in the short-term; in the long term, they can damage the liver, kidneys or central nervous system and promote cancer appearing, as in the case of benzene. In conjunction with the NO2 emitted by vehicles and sunlight, it favors the appearance of ozone, whose excess causes a reddish atmosphere known as photochemical smog, as we saw in this other article on outdoor air pollution.




Furthermore, ozone can be found as part of production processes such as drying of sausages and hams, which fulfills the mission of bactericidal and fungicidal agent as well as accelerate the dryness process. In this case, monitoring the humidity and temperature can be used to adjust ozone levels required at all times and to avoid concentrations that may be harmful to health.

In the graph below shows the different symptoms  a person may experience based on the concentration of ozone that is exposed to. The upper and lower limits correspond to the ozone sensor integrated into Waspmote. Concentrations above 1ppm can be found in food manufacturing processes (with typical concentrations between 1 to 3.5 ppm) or sewage treatment (10-20ppm).


In rural areas we also find examples of indoor air pollution due to production processes. For example, the feed storage process generates NO2, which can cause respiratory damage and even be lethal. Currently, prevention consist of not entering in the silo or in the areas annexed during the first weeks, without having the tools to know the exact concentration of the gas before entering to the stores. The humidity content of alfalfa, hay, straw, etc. at the time of storing also influences the formation of fungus and other microbial contaminants that generate acute respiratory diseases such as organic dust toxic syndrome  or the "farmer's lung."


Another manufacturing process that can be lethal is the fermentation of wine; the juice causes the release of carbon monoxide (CO) by the action of yeast as a waste product of fermentation. The repeated inhalation of this gas causes deaths for choking each year, being especially significant cases in which the wine is made using traditional methods. In order to prevent these accidents its monitoring by sensors is essential, because it is colorless, odorless and tasteless. This gas is produced by the combustion of materials such as butane, propane, kerosene, petroleum, coal, gas or wood, so it may be also cases of accidents when using stoves that are not functioning properly. In fact, the journal of the American Medical Association, JAMA, said that carbon monoxide is the leading cause of accidental death in U.S. The following table lists the symptoms that a person may suffer by inhaling CO continuously. The threshold values of CO sensor integrated in Waspmote range from the values on which is harmless, the threshold that makes a workplace unsafe (50 ppm) and the maximum threshold at which human life would be endangered (800-1200ppm). Above these values is lethal and can cause death within minutes if the concentration is approaching 4000ppm.


Pig farms generate ammonia (NH3), methane (CH4) and hydrogen sulfide (H2S). These three gases from animal droppings are toxic and can damage the lungs of humans and animals when inhaled continuously, even although in small concentrations. Losing an animal has high financial losses for the farmer, because the investment in food and vaccines can not be recovered. One of the advantages of using sensor networks to monitor gas levels present in the farm is they can be also used to monitor the temperature and humidity levels to maintain them at optimum values for the development of the offsprings.

Waspmote can monitor all the parameters mentioned in this article using the same integration sensor board. The sensors of Ozone and Volatile Organic Compounds have been recently integrated into the gas sensor board. For more information on the technical characteristics of these, consult the technical guide of the gas sensor board.

Although Waspmote is powered with batteries, it can be connected to electricity supply with an adapter, allowing more frequent sampling. Wireless communication using ZigBee /802.15.4 protocols accelerates the process of installing the sensor networks in production environments while reducing costs. Finally, the GPRS module allows the sending of real-time alerts.


If you have any questions about how to measure with Waspmote the parameters explained in this article do not hesitate to contact us.

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