美国的空气质量

What is the air quality forecast for the USA?

The United States of America (USA), also known as the United States (U.S. or US) or America, is a country mainly located in North America. It chiefly consists of 50 states and 5 territories and had a population of 328 million people in 2019.

The first recorded use of the name “America” was in 1507 when it appeared on a map produced by a German cartographer who wanted to honour an Italian explorer by the name of Amerigo Vespucci.

Looking back at the figures from 2020 on the IQAir website the US obtained an overall ranking of 84 out of a total of 106 world cities. The average annual figure was US AQI 40, in comparison to Bangladesh which was the most polluted country with a US AQI figure of 162.

The cleanest city was Waimea, Hawaii with a figure of just 9, whereas the most polluted city was Yosemite Lakes, California with a figure of 107.

Is air quality in the USA the same all year?

Last year in 2020, wildfires raged in California towards the latter part of the year. Due to climate change, they were the worst ever experienced. The skies over many of the cities were enveloped in a surreal orange-coloured smoke.

It is not always the fire itself that is the great danger, it is the tiny particles of soot that are produced by the fires that can be a greater hazard to health. These particles can be up to 10 times worse for human health than similar particles from other sources.

Overall, California has been successful in reducing pollution from automobiles, trucks and power stations, but these wildfires are getting worse. When pollution from these PM2.5 pollutants rises moderately, the admittance to medical care centres for the treatment of asthma rises by about 1 per cent. But when people inhale the particles produced by these wildfires, admittances increase by 10-fold.

Looking back at the figures recorded at that time, it can now be stated that the wildfires were responsible for 1,200 deaths and an extra 4,800 visits to emergency rooms for treatment for breathing difficulties. Most of those affected were aged 65 years or older. Many had pre-existing respiratory problems, diabetes or heart disease.

It is expected to be a similar situation in 2021 as the winter has been an exceptionally dry one. However, federal officials have signed off on an agreement that will mean stricter controls over the condition of the forested areas. Over $1 billion has been allocated for this increase in forest management, together with fuel breaks, fire inspections and an increased number of fire-crews.

It has also been suggested that more “clean room” cooling centres are made available for respite from the intense heat and offering rebates on air purifiers has also been suggested.

California possibly experienced the worst forest fires in 2020, but the rest of the country is also susceptible to wildfires which can create an equal disturbance to the air quality.

What are the main types of pollutants found in the air in America?

There are a wide variety of different chemical compounds and hazardous particulate matter in the air across the various states and cities of America. With its large and growing population, coupled with other factors such as increased vehicle ownership, there are subsequent releases of many different contaminants into the air as a result of various combustion processes.

As well as this, there are other activities that can release large amounts of coarse or fine particulate matter into the air (PM10 or PM2.5), usually through the disruption of large amounts of earth or rock through various processes such as mining and the extraction of materials, as well as construction sites or other similar areas.

Some of these chemical pollutants released from the various combustion sources include ones such as nitrogen dioxide (NO₂) and sulfur dioxide (SO₂), both of which see large amounts of release through vehicular emissions, with nitrogen dioxide being the chief offender here. It can typically be found over areas that see a high volume of traffic, so much so to the point that large accumulations of it are often strong indicators that a majority of pollution in any given area is caused by vehicles.

Both of these chemical compounds can contribute to instances of acid rain, as well as causing irritation and inflammation to the lining of the respiratory tract and lungs, causing a myriad of issues that will be discussed in more detail further on.

Other pollutants include ones such as black carbon and volatile organic compounds (VOCs), both of which are formed from the incomplete combustion of both fossil fuels and organic matter, and as such can see their creation in vehicle engines, factory boilers and even fireplaces or stoves in people’s homes (essentially anywhere that has a source of combustion taking place).

Black carbon is a major component in soot, and has potent carcinogenic properties when respired, as well as being visually unappealing, usually found coating roadside areas that see high amounts of traffic. Furthermore, it also has climate altering properties, due to it absorbing solar radiation and releasing it directly as heat, causing a warming effect to the surrounding environment.

Some examples of the aforementioned VOCs include ones such as benzene, toluene, xylene, methylene chloride and formaldehyde, all of which present a great deal of danger to human health, and are very easy to respire due to their volatile nature causing them to maintain a gaseous state even at much lower temperatures. As well as this, they are also found in many household items, being major contributors to indoor pollution, with all manner of products such as scented candles, air fresheners, aerosols and anything containing varnish or adhesives giving off some form of these chemicals.

Other prominent pollutants include ones such as methane (CH₄), released in large quantities from livestock, as well as from fertilizers. Much like many of the other pollutants mentioned, it has potent effects on both human health as well as the environment and climate.

In a similar vein, ozone (O₃) is also another pollutant of particular concern, mostly due to its prevalence amongst many cities in America. It is created when the various oxides of nitrogen (NOx) and other gases or chemicals released from cars and other similar sources, are exposed to sunlight. This causes a chemical reaction that creates ozone, or smog as it is better known when it gathers in large accumulations. Whilst this a vital part of the upper atmosphere, on ground level it can prove to have very negative health effects, hence why it is counted amongst the several pollutants that go into calculating the AQI, or air quality index.

Did COVID-19 affect air pollution in the USA?

Even though car traffic was reduced by approximately 40 per cent due to the restrictions imposed because of COVID-19, the level of air pollution remained very similar to previous records. This confirmed that factories, refineries, power stations and heavy-duty trucks are still the major cause of air pollution.

Throughout 2020, millions of cars were no longer used on a daily basis and the air became noticeably cleaner, but the level of pollutants suspended in that “clean” air remained the same.

Readings were then taken from over 900 monitoring sites which were spread across the entire US and it was seen that ozone levels were about 15 per cent lower than at comparable times from previous years. This fact alone indicates that it is going to take more than lower exhaust fumes to make a large enough difference to ozone levels.

In cities such as Los Angeles, COVID-19 seems to have played no part in the improvement of air quality. The large fleet of delivery trucks has been plying the roads as usual which proves just what a major source of pollution they are.

Looking towards the eastern seaboard, the story is very much the same. The areas around cities such as Pittsburgh are still suffering from poor quality air due to the constant use of coal in the power stations. The demand for electricity has not changed much due to COVID.

What is the cost of the USA’s polluted air to society?

It is estimated that air pollution negatively impacts the US economy to the extent of around 5 per cent of the total GDP. This figure was estimated to be in the region of $790 billion in 2014 so will be considerably more, now. The highest costs are attributed to premature deaths resulting from high exposure levels to PM2.5 particles.

Levels of air pollution have been steadily declining in recent years due to the rise in the use of cleaner energy sources such as natural gas and renewables like solar and wind power. There has also been a sharp decline in the use of coal as a source of energy in the electricity generation sector. Modern technology plays an important role too as modern filters prevent many of the toxic substances found within emissions from being emitted into the atmosphere. New catalytic converters are fitted to most engines now.

Air pollution damages are largely focussed within a small number of economic sectors: the top four responsible for the highest external damages are agriculture, utilities, manufacturing, and transportation who contribute just under 20 per cent of GDP but are responsible for more than 75 per cent of all air pollution-related damages.

Some of these emissions are declining on an annual basis as new technology is increasingly used to prevent air pollution. Unfortunately, the agricultural sector bucks the trend. The amount of pollution caused by animal husbandry and arable farming is disproportionate to their contributions to the overall GDP.

Who is most vulnerable to air pollution in the U.S.A?

As the topic of keeping oneself safe from air pollution becomes more of a pressing issue, it is of note that there are certain members of the population who are at greater risk of ill health effects from pollution exposure, particularly when it occurs over a longer period of time. Whilst even healthy adults can suffer from the negative side effects of pollution exposure, the groups that are even more vulnerable are ones such as young children, as well as the elderly.

Young children can have many allergies and other similar health problems arise during their formative years, which can go on to have lifelong consequences, with many young children who live in polluted cities developing conditions such as asthma, or allergies as well as heightened sensitivity towards certain chemicals. It can also cause higher instances of cognitive impairments due to PM2.5 particles being able to enter the blood stream and disrupt the nervous system and many other functions in the body.

Other at-risk groups include pregnant mothers, as well as those who are ill and have pre-existing conditions or compromised immune systems, a sedentary life style (with bad habits such as smoking thrown into the mix), or a combination of all of these factors. These groups should take extra care during bouts of high pollution, with staying up to date on pollution levels being of great importance, as well as taking necessary preventative measures such as the wearing of fine particle filtering masks and avoiding outdoor activities if possible.

What are some health problems associated with breathing polluted air in America?

Some health effects that occur when people breath excessive amounts of pollution in the United States can range from the temporary and superficial, all the way up to life threating and terminal. For some of the more short-term health effects, they would include instances of dry coughs, sore throats as well as chest infections. These would mostly clear up when exposure to offending pollutants is ceased, although with long term exposure they can develop into more serious respiratory conditions. These include ones that typically fall under the chronic obstructive pulmonary disorder (COPD) bracket, an umbrella term that contains within it a number of conditions such as pneumonia, bronchitis, emphysema and aggravated forms of asthma.

Other health effects include heightened risk of cancer developing, particularly if individuals are exposed to carcinogenic materials or particulates such as black carbon, finely ground silica or even VOCs such as benzene. Ischemic heart disease can present itself, along with many other dangerous health issues such as strokes, arrythmias and heart attacks. These are but a small number of the adverse effects that can occur amongst the general population, and as such it should serve as a reminder that reducing pollution, as well as keeping oneself safe from excessive exposure should become of the utmost importance in the coming years.