Qualité de l’air à Stockton

Is there polluted air in Stockton?

Stockton, located in the Central Valley region of the state of California, is a city and county seat of San Joaquin County. Stockton itself is home to an estimated 312,000 people and has a long history of being a regional transportation hub, with many agricultural products moving through the city in times past. In more recent years, Stockton has seen some rather high levels of air pollution present, with several contributing factors adding up to create such a situation. Many of these causes will be discussed in further detail in the following question, but largely they mostly find themselves emanating from all manner of combustion sources.

Looking at some more recent readings of air quality that were on record in Stockton, in early July of 2021, a US AQI reading of 20 was taken. This put Stockton into the 'good' air quality rating bracket for the particular day and time in which it was taken. This is the most optimal level of air quality and requires a US AQI reading of anywhere between 0 to 50 to be classified as such. During such bouts of lower US AQI readings, the general public will be able to conduct their day-to-day business and outdoor activities or exercise with little worry of having to deal with respiratory irritation or any other similar symptoms. Furthermore, those who belong to vulnerable groups of people will also be able to go about their day with similar lessened issues presenting themselves, although this can change rapidly with the rise in pollution levels from many different sources.

Due to sudden changes in pollution readings, it is highly advised to stay up to date on air quality forecasts and current pollution readings, which are present on both this page as well as via the AirVisual app, both of which are updated hourly with respective US AQI and other pollutant readings.

The US AQI, or United States Air Quality Index, is itself a number aggregated from the various main pollutants found in the air, both in Stockton and throughout the state. These pollutants include ones such as nitrogen dioxide (NO₂), ozone (O₃), sulfur dioxide (SO₂), carbon monoxide (CO), as well as the two main forms of particle pollution, PM10 and PM2.5. PM2.5 itself is composed of many different materials, some of which include metals, sulfates, rubber or plastic particles, soot, water or other liquid vapors, along with finely ground dust and other materials such as silica. Many of these have highly damaging properties to human health.

Out of both of the aforementioned particles, the latter (PM2.5) is the far more dangerous of the two, with its minute size of 2.5 micrometers (or many microns smaller, on occasion) allowing it to enter deep into the tissue of the lungs.

From here it can cause inflammation of the lung tissue along with irritation to the respiratory tract as well as scarring if exposure is sustained over long periods, or one particular event exposes an individual to a high amount of particulate matter. The small size allows it to enter the bloodstream via the alveoli, or small air sacs in the lungs, and once there it can cause many other health issues throughout the body. It is for this reason that PM2.5 is considered as one of the most dangerous forms of pollution present in the air, and is used prominently as a measure of air pollution, which will be discussed in further detail regarding annual pollution averages from 2020 and other years before that, going back to 2017.

Regarding further pollution readings in Stockton, it can be seen that whilst a very good quality of air was achieved in early July when looking at pollution readings from past years, one can see that both June and July maintain some of Stockton’s best air quality levels, and thus this current reading may not be truly indicative of how bad the pollution level can become. Events such as fires (which had a great deal of prominence throughout 2020 in California and throughout the Bay Area) may cause large elevations in the PM2.5 for certain months, at which time preventative measures become vital to safeguarding one’s health from the highly damaging effects that pollution or particle exposure can bring.

Other US AQI readings that were taken over both June and July of 2021 fell predominantly into the 'good' rating bracket, once again indicating a very clean level of air quality during this period of the year. However, there was one day on record in early July whereby the US AQI level rose to 52. This placed it into the 'moderate' rating bracket, which requires a reading of anywhere between 51 to 100 to be classified as such.

Although it resides on the lower end of this 'moderate' rating, it is in this bracket that health issues may begin to appear amongst the more vulnerable portion of the population. These people include young children, babies, pregnant mothers, the elderly, those with pre-existing health conditions or compromised immune systems, and those with hypersensitivity towards chemicals or particle-based pollution. Expecting mothers are particularly vulnerable, with issues ranging from premature births, babies born with low birth weight, along with increased chances of a miscarriage occurring if pollution exposure is high enough, or sustained over a long time.

This is particularly salient for the periods where smoke, haze and clouds of hazardous particulate matter may enter into the atmosphere over cities such as Stockton as a result of forest fires (with the resulting smoke being able to drift many miles and settle over cities that are great distances away from the source, causing their PM2.5 count and US AQI reading to spike significantly, as can be seen on record from 2020).

Preventative measures that individuals may employ are ones such as wearing fine particle filtering masks (preferably ones that are of higher quality, such as the masks available on the IQAir website). Staying indoors and avoiding outdoor activity or exercise can also aid greatly, along with sealing doors and windows, and running air purifiers in your home if possible. These can all go a long way in reducing the damaging effects that pollution episodes can have on people’s health, and can keep indoor pollution levels to a minimum.

In closing, overall Stockton has placed quite poorly on the global ranking chart, with many months of high pollution cropping up in 2020 and years prior. However, there are also many months with extremely good qualities of air, and as such, citizens or individuals staying in the city would do well to monitor air quality levels closely, and take appropriate measures when the pollution levels start to rise.

Why is Stockton polluted?

Stockton has numerous sources of pollution that come together to form the compounded numbers seen on record. In 2020, Stockton came in with a PM2.5 yearly average of 16.1 μg/m³, placing it into the 'moderate' rating bracket of air pollution, which when taken from the PM2.5 rating system (which differs from that of the US AQI one but still uses the same classifications), is measured in micrograms per cubic meter, or μg/m³.

This 'moderate' rating requires a PM2.5 of anywhere between 12.1 to 35.4 μg/m³ to be classified as such, and is color-coded as yellow, for ease of reference throughout the air quality graphs and maps present on this page and throughout the IQAir website. This was quite a high reading, particularly for an American city. It was placed in 1236^th place out of all cities ranked worldwide in 2020, as well as in 116^th place out of all cities ranked in California for the same year.

This is indicative that out of all the states in America, California had the highest levels of air pollution over 2020, largely due to the numerous fires that devastated vast swathes of forested areas and land over certain months of the year. This would be a significant contributor to the higher air pollution present in Stockton, skewing its yearly average and making it place significantly higher on the global circuit than it would have if the fires were absent.

However, there are still numerous other sources of air pollution present that assist in raising the yearly ambient PM2.5 count, ones that are ever-present in direct contrast to the sudden appearance (and disappearance) of fires. These include emissions and fumes from vehicles, with numerous cars and motorbikes on the road all giving out large amounts of chemical compounds and fine particles. Larger freight vehicles used in the transportation of industrial goods and other produce can also contribute heavily to vehicular pollution. These larger vehicles, which include trucks, lorries and buses, oftentimes utilize diesel as a fuel source, and as such, individual units can give out far more pollution than a single smaller vehicle could.

Adding to this is the issue of microscopic rubber particles entering the atmosphere (which have numerous adverse health effects on human health, wildlife and the environment, much in the same vein that microplastics do). These are churned out in many tons from the residual wear and tear of tire treads, contaminating the air, as well as bodies of water and the ground.

Other prominent sources of pollution would be emissions from power plants, factories and similar industrial sites. The use of fossil fuels is also prevalent in such facilities, and although many measures are being (and have already been) put into place to lower their usage, the combustion of such material leads to a significant release of particle pollution, amongst others. In closing, the largest contributor to air pollution in Stockton over 2020 was smoke from fires started around the state, followed by the other ambient sources mentioned above.

What risks come from breathing polluted air in Stockton?

Health risks that can arise from breathing polluted air, particularly during the higher spells include conditions such as chronic obstructive pulmonary disease (COPD), an umbrella term that includes ailments such as bronchitis, emphysema, pneumonia and asthma.

Higher pollution exposure can also increase the risk of skin and lung cancer, along with other skin conditions such as atopic dermatitis, acne, eczema and psoriasis. Dry coughs, chest pain and irritation to the mucous membranes such as the eyes and mouth may also present themselves (particularly amongst sensitive individuals).

More serious or terminal conditions also include a higher risk of heart attacks, arrhythmias, ischemic heart disease, strokes, and even death, with many cases of premature death becoming increasingly linked to pollution exposure, both in the state of California and throughout the world.

When is Stockton at its most polluted?

Looking at the air quality data that was on record from 2020, it can be seen that Stockton had many months where the PM2.5 levels were significantly higher than its cleaner ones, with the most polluted month (September) coming in nearly 10 times greater than that of its cleanest month, in terms of the PM2.5 count. January and February both came in with 'moderate' readings of air pollution, whilst August through to November also came in as moderate and above.

September, as mentioned, had the highest reading, coming in at 37.7 μg/m³. This placed it in the 'unhealthy for sensitive groups' rating bracket, which requires a PM2.5 reading of 35.5 to 55.4 μg/m³ for classification. As the name implies, those with pre-existing health conditions or individuals belonging to the aforementioned at-risk groups are at significantly greater disposition towards suffering from negative side effects.

Is the air quality in Stockton clean at certain times?

Observing the air quality data from 2020 once again as a reference point, it can be seen that Stockton had several months that had a very respectable level of air quality, whereby the atmosphere would be significantly freer from smoke, haze, smog and damaging particles.

The months that came in with the best readings of PM2.5 were March through to June, which presented with PM2.5 figures of 6.6 μg/m³, 4.2 μg/m³, 4.3 μg/m³, 5 μg/m³ and 5.9 μg/m³. All of these months fell well within the World Health Organization's (WHO's) target goal for the most optimal level of air quality at 10 μg/m³ or less, with April being the cleanest month of the year with its respectable reading of 4.2 μg/m³.