Qualité de l’air à Raleigh

Is Raleigh a city with good air quality?

Raleigh is the capital of the state of North Carolina in the United States. It is informally known as the "City of Oaks" for its many oak trees, which line the streets in the heart of the city. The 2019 census estimated the population as being slightly less than half a million people. It is seen to be one of the fastest growing cities in the US.

Does the air quality in Raleigh vary throughout the year?

In 2020, according to figures just released on the IQAir website, Raleigh recorded an average total of 9.8 µg/m³ which is less than the WHO target of 10 µg/m³. It achieved this number for 5 months of the year. In March, June, August, October and November, Raleigh enjoyed “Good” quality air with readings between 10 and 12 µg/m³. During July and December, the quality was slightly worse with figures between 12.1 and 35.4 µg/m³.

Looking back at figures from 2019, it can be seen that during the months of March, April and October, Raleigh, once again, achieved the WHO target figure. For May, July, September and November the readings showed a “Moderate” quality of air with measurements between 12.1 and 35.4 µg/m³. For the remaining 5 months, the air quality was “Good” with figures between 10 and 12 µg/m³.

Looking back over previous years, the quality is getting slightly worse. In 2017 Raleigh attained the WHO target of 9.4 µg/m³, in 2018 it was 9.8 µg/m³ whereas in 2019 the slight decline revealed a figure of 11.3 µg/m³.

What is the source of air pollution in Raleigh?

Compared to the 2017 report, some North Carolina metro areas have seen an increase in ozone (O₃) pollution slightly. This is in keeping with a trend seen across the nation of higher ozone pollution levels.

Particle pollution often contains soot (BC) or tiny particles PM2.5 and PM10 that come from coal-fired power plants, diesel emissions, wildfires and wood-burning devices. These particles are so small that they can lodge deep in the lungs and trigger asthma attacks, heart attacks and strokes, and can even be lethal.

People tend to think that the air inside a building is so much cleaner than the outdoor air. This is in fact the exact opposite of the truth. Indoor air can be three or four times worse than the air outside. The reason for this trouble with indoor air quality is that the insulation on buildings makes it harder for the contaminants that build-up inside to escape as fresh air replaces stale air.

Outdoor air pollution can be a mixture of natural and man-made particles found in the air. Regular exposure to it can harm our health when we breathe it.

Many things can cause poor air quality. For example, in a city, air pollution can be caused by emissions from vehicles. This is called ground-level ozone (or urban smog). Ozone is a gas and accounts for a large part of air pollution. Tropospheric ozone increases in cities when the air is not moving, the temperature is warm, and the sun is shining. This combination traps pollution in the air.

Aeroplanes also produce a considerable amount of air pollution. Construction vehicles and tobacco smoke can also cause it. In rural areas, outdoor air pollution is often caused by dust from tractors ploughing fields, trucks and cars driving on gravel roads, rock quarries, and smoke from wood fires and burning crop residue.

Can anything be done to protect yourself against the poor air quality in Raleigh?

The Environmental Protection Agency (EPA) regularly measures the air quality of cities and rural areas and reports on it. Because of this, air quality has improved during the last two decades. Local television and radio as well as digital sources will often publish the results online.

Do not go out when there is a lot of pollution. Use the ICA to determine how much time to spend outdoors. While you will have to go to work or school, try to avoid optional outdoor activities on days when the ICA is high.

Choose another day to go to the park or work in the garden. If you must be outdoors on days when the ICA is high, limit activity to the early morning or evening. Scheduling the hours is important if you live in a city because sunlight can increase ozone levels. High ozone levels can make it difficult to breathe outdoors if you have lung problems.

Try to avoid strenuous physical activity on days with high air pollution. Physical activity can make your breathing stronger and faster. The faster you breathe, the more air pollution you'll inhale.

Breathing ozone and particle pollutants can cause asthma attacks, respiratory and cardiovascular harm, and even early death. Breathing particle pollution can also cause lung cancer. Ozone especially harms children under the age of 14 years, older adults and those with asthma and other lung diseases.

What are the health effects of breathing Raleigh’s poor quality air?

Scientific evidence indicates that lung damage that is caused by prolonged exposure to lower levels of ozone-polluted air poses the greatest health risk. Averaging ozone levels for eight hours provides a higher level of protection, especially for children under the age of 14 years and those adults who spend a significant portion of their time working or playing outdoors which is a group that is particularly vulnerable to the effects of ozone.

The standard for airborne particulates up to 10 microns in diameter (PM10) remains in effect. But now, EPA says that air pollution with smaller particles measuring less than 2.5 microns in diameter (PM2.5) is a worse health concern because of their microscopic size they can easily bypass the body’s defence mechanism and get deep into the respiratory system. Breathing air polluted with fine particles can have detrimental health effects such as including premature death and an increase in respiratory illnesses.

Particulate matter (PM) is the term used for a mixture of solid and liquid particles found in the air. It originates from a variety of sources including automobiles, power plants, construction activities, soil dust, soot, and industrial processes. Coarse particulates (PM10) are generally emitted from sources such as wind-blown dust, vehicles travelling on unpaved roads, and rock/stone crushing and grinding operations. Fine particles (PM 2.5) can come from the combustion of fuels (cars, power generation, industrial plants) and fugitive dust. Fine particles are formed mainly in the atmosphere from gases such as sulphur oxides, nitric oxide and VOCs.

Many residents experience some type of symptoms related to air pollution, such as watery eyes, coughing or noise when breathing. Even for healthy people, polluted air can cause irritation or breathing difficulties during exercise or outdoor activities. Your actual risk depends on your current health status, the type and concentration of the pollutant and the length of time you have been exposed to the polluted air.