The Need to Measure Air Quality and How It is Done

Air is a critical resource and needs to be free from pollution that often affects most of our cities. Industrialized cities have factory smoke, while pollution from internal combustion engines that most automobiles use, do create haze and smog over a city. City authorities struggle to curb pollutants and curb emissions in order to make the air in cities more breathable. This process has been helped by measured data that governments and various regulatory bodies have access to, which allows them to judge the degree of pollution, identify its source and find punitive or corrective measures to reduce pollution and improve the quality of air.

air pollution globally

Humankind faces many environmental challenges and in cities and large urban conglomerations, air quality is the one that is the most difficult to manage. The reason for this is that there is a quick diffusion of air pollution and it makes everyone in that particular area or those adjacent, suffer the ill effects of pollution and having to share the costs of poor air quality. These costs are largely caused by poor respiratory health, and other ill effects of pollution come from chemical reactions with structures and building and even the trees and green cover. When any regulation is put in place to tackle pollution, it becomes difficult to track down the source of the emissions that are harmful due to the pollution getting diffused quickly. Most of this pollution remains difficult to see, and this lack of visibility makes it hard to pinpoint the source. Actual fires and smoke, like from power stations and other industrial chimneys may be easy to detect, but there are already laws in place that govern the height and configuration of chimneys, which are meant to carry the emissions to heights where they can be easily dispersed. It is, however, not clearly established, whether these regulations, some of them quite antiquated, actually do reduce the pollution and damage to the environment surrounding the chimneys. In fact, it has been now understood, that power stations that produce the vital resource of energy are very high contributors to pollution and this is aggravated by the environmental damage caused by the solid waste products that power production does generate.

It is now clear that any attempt to reduce pollution is expensive, and this makes industries and others responsible for the deterioration in air quality reluctant to take the necessary steps to make any changes that can benefit air quality. That is the reason, that the world over, governments have taken it on as one of their most important jobs. They have understood that poor air quality has a number of negative impacts on the health of their citizens, and this can result in more respiratory diseases, acute asthma, and an elevated risk of heart disease and other cardiovascular problems. Pollution has also been linked to higher incidences of cancer and other reproductive and problems for the development of children.

Air Pollution By NO2

Cities are now establishing stations that monitor air quality and give them the necessary data, that allows them to pinpoint sources of emissions and to find ways to curb them. A sensor network supplemented by high tech cameras allow the monitoring of pollution events and GPS helps to track their locations. These sensors measure temperature, vibration, light and other air quality components like carbon monoxide, and nitrogen oxide, while others take air samples to determine the particulate matter and other volatile organic compounds. The six pollutants that have been identified as being mainly responsible for air pollution are ground-level ozone, carbon monoxide, nitrogen oxides, sulfur oxides, lead and particle pollution or particulate matter. The main sources of this pollution come from trucks cars, buses, trains, planes which are mobile, stationary sources like oil refineries, power plants, factories and industries, and area sources like wood and charcoal burning, agricultural waste, and livestock.

pollution from factories

Ozone is good for reducing the effect of ultraviolet rays from the sun, but ground-level ozone is that which is created by chemical reactions between nitrogen oxides and volatile organic compounds during the daytime when there is sunlight. It can have a harmful effect on ecosystems and vegetation that is sensitive to it. Breathing the ozone can lead to throat irritation, congestion, coughing, and chest pain. It further reduces lung function and inflames the lining in the lungs, leading to the permanent formation of scar tissue in them.

Air quality can be measured by simple physical and chemical methods though these are rapidly being replaced by more sophisticated techniques that use electronics. The simplest and cheapest way of measuring air quality is by analyzing the quality of air. This can be a good indicator of the pollution concentrations spread over a period of time, that can be measured in weeks or months. These samplers are passive because they do not involve any pumping or physical pumping. Diffusion is the physical process used with the employment of diffusion tubes that act as passive samplers. They are used for pollutants like benzene and nitrogen oxide. These tubes are 11mm in diameter and 71 mm long. and have gauzes made of stainless steel placed at the end of a cylinder that is quite short. These gauzes are coated with triethanolamine which converts any nitrogen oxide that touches it to a nitrite. These nitrates get trapped in the gauze that can then be sent for analysis. The diffusion tube is open to the atmosphere at one end, and for the collection of samples, this open end is kept downwards so that it remains unaffected by dust or rain. Once the tube has been exposed at any one site, it is then sealed, its location properly marked and these tubes are then collected at regular intervals and sent to a laboratory for analysis.

smoke from factories

The active sampling of air for determining air quality involves physical or chemical methods to collect air from the site whose pollution is to be measured so that it can be sent to a laboratory for the necessary analysis. The air of a definite volume is pumped through filters or chemical solutions for a predetermined period of time. The air so collected is then sent to laboratories for the necessary analysis after the locations, and time is carefully marked. The period between samples is as determined by the requirements of the authority monitoring air quality.

factories harmful gases

Some monitoring agencies use automatic methods that measure air pollutants on an hourly basis at a single point. The analysis of samples is carried out through methods like spectroscopy and gas and the analysis is carried out for particulates, carbon monoxide, sulfur dioxide, nitrogen oxides and ground-level ozone. Once the samples are analyzed they are downloaded in real time to monitoring agencies and thus provide accurate information that allows for an instant action that may be desired. Spectroscopic techniques also can use long-range remote optical methods to measure pollutants.

Immaterial of the method used to measure air pollutants, their concentration in the air is what helps to determine the air quality index. The standard used generally parts per million or any other large number as required by the set standards, by volume. They are often measured by weight of the pollutants in a given volume of air. It is not possible to measure the extent of pollution in every place, and often experts use modeling techniques where models are used to simulate the dispersion of the air pollutants from the source where they are created. This enables an estimate of ground-level pollution at places where no actual analysis has been carried out. The use of computers has given a greater scope for such simulations to judge air quality in widely dispersed areas. The accuracy of such analysis based on models depends on the quality of the data that is being used and requires to be periodically confirmed with actual site analysis of air samples. Variations in weather conditions that cause pollution emissions can also make such a technique uncertain.

Statistics on air quality are nowadays widely disseminated so that they are available to anyone who is interested. Authorities and event managers do use them to guide them in the conduction of events where there is a large public presence, especially those of children. They are often used by airports and other public services to help them to plan activities. It is also used by legislators to identify sources of pollution that can be then controlled or monitored.

It is known that air pollution can be transmitted across borders and far away from the actual source causing these emissions. This has led to the need for international standards and agreements to control these so that one country producing pollution is not absolved of responsibility, as the deterioration in their air quality is actually affecting another country and not their own. Air pollution and environmental damage can also affect water sources and this allows the pollutants to travel large distances. Pollution of the air can also affect global warming which is rapidly becoming a major international concern. Measuring air quality in all parts of the world has, therefore, become a major concern for governments.

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