Air quality in Santos

What is the current level of air pollution in Santos city?

Santos is a municipality in the Brazilian state of São Paulo. According to a 2020 census, Santos had an estimated population of approximately 434,000 people. It is located partially on the island of São Vicente and partially on the mainland. The island is also home to a city of the same name, São Vicente.

The state of the air in August 2021 was “Unhealthy for sensitive groups” with a US AQI reading of 120. This United States Air Quality Index number is calculated using the levels of six of the most commonly occurring air pollutants, such as nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and both sizes of particulate matter, being PM2.5 and PM10. It can then be used as the metric when comparing air quality in other cities around the world. If data is unavailable for all 6 pollutants, a figure can still be calculated by using what figures there are. For Santos City readings were available for three pollutants which were; PM2.5 - 23 µg/m³, PM10 - 46 µg/m³ and sulphur dioxide (SO₂) - 1 µg/m³. The level of PM2.5 is just over twice the recommended level of 10 µg/m³ which is the suggested maximum figure by the World Health Organisation (WHO), although no amount of air pollution is considered to be safe.

With pollution at this level, the given advice would be to stay inside and close all windows and doors to prevent the ingress of more dirty air. Those who are sensitive to poor quality air should avoid exercising outside until the air quality improves and if venturing outside is unavoidable, then the wearing of a good quality face mask is essential. The table that is published at the top of this page should help with that decision or download the AirVisual app for constant updates as to the state of the air on the move.

Does the level of air pollution in Santos vary throughout the year?

Air quality can be very volatile and can therefore change very quickly depending on the current meteorological conditions. During 2020, the months that provided the cleanest air were November, December and January with figures from the “Good” air quality bracket with readings of 11.2 µg/m³, 11.1 µg/m³ and 11.7 µg/m³, respectively.

To qualify for this classification, figures need to be between 10 and 12 µg/m³. The remainder of the year brought “Moderate” quality air with figures between 12.1 and 35.4 µg/m³ to qualify as such. The worst months were from May through until August with figures around 15 and 16 µg/m³.

Historically, records have been kept since 2017 when the average annual figure was noted to be 15.9 µg/m³. A slight improvement was recorded the following year with a figure of 14.8 µg/m³. But then the quality slipped again in 2019 to 15.4 µg/m³. In 2020 a figure of 13.7 µg/m³ was recorded which would be classified as being “Moderate” but this reading may have been affected by the COVID-19 situation as many vehicles were no longer in daily use in an attempt to halt the spread of the virus. Many factories and non-essential production units were also required to close which removed their emissions from the atmosphere.

Is there a main source of air pollution in Santos?

Air quality is directly influenced by the distribution and intensity of air pollutant emissions from vehicular and industrial sources. Topography and meteorological conditions play a fundamental role, which changes significantly in the various regions of the state. Vehicle emissions play a prominent role in air pollution levels in large urban centres, while industrial emissions significantly affect air quality in more specific regions.

According to research, the vehicles, in addition to emitting carbon monoxide through the exhaust, also emit polluting particles with the abrasive action of the tire on the asphalt and the use of their brake pads. These microscopic particles eventually find their way into the food chain by being deposited on the land where plants are growing.

Another reason for greater pollution is the drier climate in recent times. As the temperature drops during winter nights, warm air rises and pollutants become trapped at a height of about 160 meters above ground level. These particles cannot break the cold air barrier and remain there until it gets hot. By mid-morning the pollution disperses because the warm air has already reached the upper layers and the barrier is broken. This typical winter condition is called a thermal inversion.

If it rains, the rain makes a general cleaning of all particles. In winter there is little rain and wind and this enables the pollutants to remain in the atmosphere. If it starts to rain and we have a better condition, the pollutants also decrease.

What can be done to reduce air pollution in Santos?

There are several programs such as the Vehicle Pollution Control Plan, the Stationary Sources Emission Reduction Plan, in addition to the inspection and control of industrial emissions and the program for the inspection of smoke from diesel vehicles (Black Smoke).

Parks are great initiatives for environmental improvement. But for air quality, the number of cars on the streets must be reduced. This can only be achieved with a significant improvement in the public transport network and a focus on transports that do not emit pollutants, such as the cycle paths and the subway.

What are the health impacts of breathing dirty air in Santos?

Pollution can either cause new diseases or exacerbate existing ones. Those who have asthma or chronic bronchitis, for example, may experience worsening of the condition when exposed to a high concentration of pollutants.

Healthy people can develop acute illnesses such as respiratory infection and asthma or milder problems such as rhinitis and a runny nose.

Some symptoms caused by dirty air are easy to notice, such as dry throat and mouth, shortness of breath, and coughing. They are the body's attempts to expel intruders that enter the respiratory system. But there are also silent signs, such as the increased risk of heart attack, obesity, memory impairment and even impact on fertility.

The low immunity of the elderly and children makes these two groups more susceptible to harm caused by pollution. Babies suffer even more. “Children's airway calibre is smaller than that of adults, which facilitates obstruction. Furthermore, as their immune system has a lower response, they are more susceptible to viruses, and pollution increases the circulation of viruses.