Air quality, a silent hazard
Global warming affects plants and animals. Changes in the flowering of some species have already been detected due to the rise in winter temperatures. This means that the pollen season has been extended. Therefore, people who suffer from pollinosis or hay fever are exposed to longer periods with pollen. Also, an increase in the atmospheric CO2 encourages the biological activity of the plants and the photosynthesis, which also means an increase in the pollen content in the atmosphere. In Spain, hay fever affects approximately 15% of the population. This percentage rises to 30% amongst young people, according to data from the Ministry of Health. This situation can also make other allergic diseases worse, such as asthma, rhinitis, allergic conjunctivitis or several types of dermatitis, particularly in urban areas.
But urban atmospheric pollution continues to be the most important environmental problem in the world. The World Health Organisation has recently estimated that 3.7 million deaths a year in the world could be attributable to atmospheric pollution and in 2013 the International Agency for Cancer Research classified exterior air pollution as carcinogenic. Pollution increases the risk of suffering from acute respiratory diseases such as pneumonia, as well as chronic ones, such as lung cancer and cardiovascular diseases. The people who are most sensitive to pollution are the ones who suffer chronic respiratory disorders (COPD; chronic bronchitis, asthma…), cardiovascular diseases and diabetes, as the atmospheric pollution can aggravate the effects of these diseases. Children are also affected because their respiratory system is not completely developed and they breathe more air per weight unit than adults.
Effects on water and food
The high temperatures can heat the water in the reservoirs and lakes, encouraging the proliferation of cyanobacteria (algae), which could be a health risk due to its toxicity for humans. In the case of seas and oceans, the warming causes the migration of species, the presence of jellyfish and cyanobacteria and an increase in food poisoning from shellfish and reef fish.
The amount and quality of the water can also affect agricultural production and increase the risk of diseases transmitted by food, as well as malnutrition. Agriculture uses 70% of the water that is extracted around the world and on a global scale, over 330 million hectares use irrigation systems. Irrigated agriculture represents 20% of the entire cultivated surface area and provides 40% of the total food production in the world.
Vector-borne diseases
Parasites, bacteria and virus transmit the so-called vector-borne diseases. Their survival varies in terms of the humidity and above all, the temperature, but also according to the altitude above sea level, the wind and the length of the day. Climate warming has meant an increase in diseases produced by these vectors, such as malaria, dengue fever or leishmaniosis. Malaria is transmitted to humans by infected mosquitoes of the Anopheles genus. It was endemic in Europe, but was eradicated in the 1970s. The experts consider it unlikely to be reintroduced on the continent in spite of the increase in temperatures.
Leishmaniasis is another disease transmitted by phlebotomine sand flies. It is present in Europe and it is endemic in Spain. Over 50% of infected dogs are asymptomatic carriers and can transmit the parasite to mosquitoes, particularly in rural and residential areas. Leishmaniasis is considered to be a disease associated to climate change and recently maps of risk have been prepared, according to the possible climate change scenarios.Dengue fever is a fundamentally an urban disease, caused by the dengue virus and transmitted by the bite of a mosquito of the Aedes species. The World Health Organisation calculates that between 50 and 100 million dengue infections occur every year in the world. In Europe, the first two cases of native dengue fever were detected in France and one case of a German tourist from Croatia in 2010, along with the outbreak in Madeira between 2012 and 2013. The presence of the mosquito that transmits dengue fever has also been detected in the Catalan region of Spain.
