Indirect health effects of climate change
Indirect health effects of the climate may be transmitted in ecosystems and the services they produce, including changes in the quality of water, soil and air quality. Climate change can also cause changes in people's behaviour, while changes in the species populations have an effect on the availability of nutrition or prevalence of animal-transmitted diseases.
In addition, climate change can harm our health via major disturbances in systems, such as disruptions in electrical power supply and heat distribution. Extent of the eventual impacts depend on the adjustability of these systems and the availability of necessary health services to different population groups. Nearly all presumed health effects of climate change are related to the problem of them being unpredictable. In the case of diseases and deaths, there may be several underlying factors, and health hazards occurring in the environment take an effect in them concurrently.
Climate change may weaken air quality
Together with fine particles, ground-level ozone is considered the worst air quality problem in Europe. Even minor elevations in the ozone concentrations from the normal background values may be detrimental to health [1]. In the lower atmosphere, ozone is detrimental to humans whereas in the upper atmosphere, ozone is vital as it protects the earth from UV radiation.
Since lower atmosphere ozone is created in chemical reactions that are accelerated by warm and dry air, elevation of the average temperature and decreased rainfall during summer may have a negative effect on the air quality. It has been proven that variations in the climate and climate change have caused ozone concentrations in the lower atmosphere to increase in Central and South-West Europe and elevation of the ozone levels caused by climate may impede the attempts to control ozone levels [1].
If the nitrogen oxides created mainly by traffic cannot be limited, climate change can promote the rise in lower atmosphere ozone levels in Finland, particularly in the summer. High ozone concentrations cause difficulties especially for asthmatics, elderly people, people working outdoors and athletes. In addition to ozone, forest and wildfires caused by drought which have become more common in Finland and its neighbouring countries can deteriorate the quality of air and cause health hazards, particularly for people suffering from asthma.
A warming climate can be reflected as allergies
Along with climate change, the distribution area of many plant species found in Finland may gradually extend further north. If the distribution and flowering time of allergy-causing plants, such as mugwort or birch, change this may be reflected as time changes in the occurrence of allergy symptoms on the population level [1].
Figure. Birch pollen is a notable cause of allergy.
© SYKEkuva
If the growth season begins earlier in the spring – as is expected – the warming climate can launch the pollen season earlier than before. In addition, warming can promote the distribution of new allergy-causing species into Finland and the prolonged growth period extend the pollen season nation-wide. However, the changes underway are slow, and so far, no increase in allergy cases has been proven.
There is only little research regarding the effect of climate change on allergies caused by mould, yeasts and toxic algae [1]. Global warming and increase of floods and rain during winter may have an effect on their prevalence and thus to allergies and respiratory diseases related to organisms. If the changing climate is not taken into consideration in new and renovation building, mild winters with amply of rain may increase damp damage in buildings for their part.
Effect of climate change on the prevalence of infections
Should the mild winters lead to an expansion in the tick population that spreads the Borrelia bacteria and tick-borne encephalitis, humans may become more extensively exposed to Lyme borreliosis and tick-borne encephalitis [1].
In addition, if mild winters are followed by damp summers, the ticks' living conditions may be further improved. According to a study conducted in Sweden, a late winter increased the prevalence of these infectious diseases, although changes in land use taking place in farming and forestry explained the occurrence of the disease to some extent [1].
Climate change may also have an effect on the prevalence of epidemic nephropathy if the breeding conditions of moles change. Moles spread the Puumala virus that causes epidemic nephropathy in humans. The possible effect of climate change on the quantity of moles is currently under investigation in Finland [1]. The warming climate has not been found to have an effect on the prevalence of respiratory infections, including flu and influenza viruses.
Effects allocated at the quality of food and water
Incidence of food poisonings and Salmonella bacterium, among others, depends on the temperature. Since infectious diseases susceptible to heat – e.g. salmonella infections – are likely to become more common in the future, special attention must be paid to the hygiene of foodstuffs and an unbreakable cold chain as the climate becomes warmer and the number of hot days increases [1].
On a global scale, heavy rain and flooding will cause the most deaths directly caused by weather conditions [2]. Drinking water may also be contaminated by downpours, floods or surface runoff caused by snow and thus cause water-mediated epidemics in situations when the capacity of water purification plants is insufficient due to floods or sanitary service being non-operational. In addition, higher water temperatures can cause an increase in the occurrence of harmful algal blooms [1].
Preparing for the indirect health effects of climate change
More information is required regarding the indirect health effects of climate change and the means to adapt to them. Although many of the effects are already familiar, their occurrence and severity may change in the future. In addition, many preparatory means are already partially in use. For example, air pollution is monitored and notified in the whole of Finland. The metropolitan area municipalities, for instance, have drawn up action plans to improve air quality and prepare for poor air quality [3]. In a warming climate, even more attention should be paid to the hygiene and cold storage of foodstuff. Possible detrimental health effects can be prevented by ensuring that the foodstuff cold chains remain unbroken [4].