The influence of heat wave
The most direct impact of climate warming on human health is to increase the frequency or severity of heat waves. Heat wave and high temperature make germs, viruses and parasites more active, which will damage human immunity and disease resistance, leading to an increase in the incidence and mortality of heart and respiratory diseases related to heat wave. This effect is particularly significant for the elderly, children and poor groups in developing countries. The World Health Organization predicts that by 2020, the number of people dying from extreme high temperature will increase by 1 times. People have done a lot of research on climate warming and mortality changes, and put forward the concept of "thermal threshold". When the temperature rises above the "thermal threshold", the mortality rate increases significantly. For example, during the heat wave in Los Angeles, the death rate of the elderly over 85 was eight times as high as usual. The research results of Shanghai 1980- 1989 show that the mortality rate rises sharply when the temperature exceeds 34℃ in summer. 1998 Shanghai experienced the worst heat wave in recent decades (July 8 -20, August 1-3, August 7- 17, August 23-25), and the death rate during the heat wave was 2-3 times that of usual. Similar studies in Portugal, Japan, Canada, Egypt and other countries have also found the same pattern. As can be seen from Figure 1, the daily death toll in Portugal increases with the increase of temperature, and the extreme maximum temperature corresponds to the maximum death toll.
The impact of heat wave on human health is greater in cities than in suburbs and rural areas. Due to the heat island effect, the high temperature in urban areas is not only high, but also lasts for a long time, which is harmful to human health.
(2) photochemical effect
Climate warming will accelerate the photochemical reaction between chemical pollutants in the atmosphere, cause the increase of harmful oxidants such as photochemical aerosols and induce some diseases. Such as eye inflammation, acute upper respiratory diseases, chronic bronchitis, emphysema and bronchial asthma.
Ultraviolet rays can effectively kill bacteria and viruses, enhance human immunity, promote the absorption of trace elements such as calcium and phosphorus, and contribute to the growth and development of human bones. However, excessive ultraviolet rays will do harm to human health. Climate warming, the increase of greenhouse gases such as chlorofluorocarbons in the atmosphere, and the destruction and thinning of the ozone layer lead to the increase of ultraviolet rays on the ground, especially the increase of UV-B, which is very harmful to human health and will cause diseases such as cataracts and skin cancer. Some types of cataracts are directly related to the cumulative exposure to UV-B. Every decrease in stratospheric ozone 1% is accompanied by an increase in UV-B, and cataract patients increase by 0.6%. Recent research in the United States shows that the reduction of 1% ozone and the increase of UV-B will increase the incidence of skin cancer in Caucasians by about 3%. Excessive ultraviolet radiation can damage NDA (gene poisoning), mutate daughter cells and lead to skin cancer.
Studies have shown that excessive UV-B radiation will destroy the immune system of human body, thus reducing the ability of human body to resist diseases.
Second, climate warming is conducive to the spread of pathogenic sexually transmitted diseases.
Many pathogenic vector-borne diseases are temperature-sensitive diseases, and climate warming has contributed to the spread of some vector-borne diseases.
Promote the spread of insect-borne diseases: insect-borne diseases are diseases in which pathogens spread through insects as intermediate hosts or parasites, and then spread to people. Climate warming will change the climate zone, and the boundary of tropical zone will expand to subtropical zone, which will expand the geographical distribution of insect-borne diseases, move the endemic area northward and increase the spread of insect-borne diseases. For example, tsutsugamushi disease in southern China appeared in Tianjin in 1989 and 1990, which pushed the endemic area of tsutsugamushi disease northward by four latitudes. Climate warming and its extreme weather events have seriously affected the ecological balance, especially the microbial ecological balance. It has changed the survival, variation, distribution and prevalence of some insect-borne pathogens, and will promote the spread of insect-borne diseases such as malaria, filariasis, schistosomiasis, dengue fever, yellow fever, rift valley fever and encephalitis, and make some insect-borne diseases resurface. For example, due to climate warming, Anopheles mosquitoes that have disappeared in the United States have reappeared in some areas. With the climate warming, dengue fever has made a comeback in some places, and reappeared in extinct Caribbean, Brazil, Peru and other countries. In recent 20 years, dengue fever has also broken out in Guangdong, Guangxi and Fujian provinces. 1995, the world health organization issued a warning that dengue fever is prevalent worldwide, causing about 20,000 deaths every year and threatening the lives of about 50 million to 1 100 million people in tropical and subtropical countries. With the climate warming, insect-borne diseases such as malaria, blood-sucking diseases and dengue fever will affect the health of 40%-50% of the world's population.
It has contributed to the spread of animal-borne diseases: due to climate warming and its environmental changes, it has contributed to the survival, variation and spread of pathogens of animal-borne diseases. (For example, with the climate warming, pathogens will break through their parasitic and infected distribution areas and form new infectious diseases, or gene exchange between an animal pathogen and wild or domestic animal pathogens will make pathogens put on new coats, thus avoiding the human immune system and causing new infectious diseases. With the warming of temperate climate, the distribution area of rodents infected or carrying pathogens has expanded, the annual damage period has been prolonged and the infected areas have spread. Some animals carry pathogens or viruses that can be transmitted to humans, causing diseases in humans and animals. For example, AIDS originated from African primates; Mad cow disease and bird flu are diseases of dairy cows and poultry respectively; Nipah disease was transmitted to You Zhu and humans by Malaysian bats carrying the virus.
Contribute to the spread of water-borne diseases: Climate warming may worsen water quality or lead to floods, thus contributing to the spread of some water-borne diseases. In some land areas with more precipitation, due to the rising water level, the surface water quality that people drink decreases due to surface material pollution, and people are prone to water-borne diseases such as skin diseases and gastrointestinal diseases after drinking. With the change of living environment, water shortage intensifies, sanitary conditions are poor, and people's resistance declines, which will make cholera, dysentery and other water-borne diseases popular. For example, cholera hit Peru on 199 1 and spread rapidly to Ecuador, Colombia, Chile, Brazil and other Latin American countries 19, resulting in more than 500,000 people suffering from cholera and nearly 5,000 deaths.
With the climate warming, pathogens will break through their original parasitic and infectious distribution areas, and may form new infectious disease pathogens. According to the report of the World Health Organization, at least 30 new infectious diseases have appeared in the past 20 years. The emergence of various new infectious diseases viruses is the result of human activities destroying the ecological environment and climate warming disturbing virus nests. Some unknown viruses that originally lived in wild animals and moved in the closed world were encountered due to the process of human activities. Infectious diseases caused by new pathogens are the most harmful to human beings. For example, in the 22 cases of Legionella outbreak in 1976, 34 people died, and the mortality rate was as high as15.6%. AIDS, first discovered in the United States at 198 1, has spread all over the world, with more than 40 million people infected with HIV worldwide. American scientists have warned that with the continuous warming of the climate, some unknown viruses may revive and spread everywhere, which may bring greater disasters to human health.
Three. El Nino phenomenon and human diseases
El Nino phenomenon is a complex climate phenomenon caused by the imbalance of interaction between ocean and atmosphere in the Pacific equatorial belt. It occurs 1 time every 2-7 years, and causes climate warming and extreme weather events, which bring harmful or even huge destructive effects to human health and life. El Nino will increase the spread of malaria and other diseases in some countries and regions. Some experts from Venezuela and Colombia have systematically studied the relationship between El Ni? o and malaria epidemic. The results showed that in the first year of El Ni? o, the number of malaria patients increased by 37% in Venezuela and 35. 1% in Colombia. During 1997- 1998, high temperature and floods occurred in Somalia, Kenya and Ecuador, and 89,000 people were infected with Rift Valley fever. Widespread droughts in Venezuela, Brazil and other countries have led to outbreaks of malaria and scarlet fever, causing many deaths.
Fourthly, the possible relationship between SARS, avian influenza and climate change.
Both traditional medicine and modern epidemiology believe that the occurrence and spread of infectious diseases are closely related to climatic conditions. The existing research results show that the maximum temperature, daily range and relative humidity are closely related to the spread of SARS. When the maximum temperature is relatively low (below 26℃), the daily temperature difference is small and the relative humidity is high on 9- 10 after the outbreak of SARS virus, it is beneficial to the spread and spread of SARS virus. On the contrary, it is not conducive to the spread and spread of SARS virus.
Comparing the statistical chart of daily confirmed SARS cases in Chinese mainland with the evolution curve of the highest temperature in Beijing-Guangzhou during the same period, it is found that the average highest temperature in February and April during the high incidence of SARS in the two cities is 19-24℃, which is a favorable climatic condition for the breeding and spread of SARS virus. The monthly average maximum temperature of 20-23℃ is most conducive to the spread of SARS. The study also found that the small daily temperature difference is beneficial to the occurrence and development of SARS; When the temperature difference of the day is large, it is not conducive to the rapid occurrence and development of SARS. Humidity in the air may be one of the favorable factors for the reproduction of SARS virus.
Some preliminary research results at home and abroad show that climate warming may contribute to bird flu. Climate factors must have played a role in the spread of avian influenza. Migratory birds have become the main vector of avian influenza virus, and their living habits are closely related to the climate. Both the World Health Organization and the Ministry of Health of China pointed out that avian influenza virus is sensitive to heat and ultraviolet rays. 97% of human avian influenza cases in China occur in subtropical monsoon region, which is probably related to the climate characteristics in this region. The optimum temperature for avian influenza virus transmission is 10-20℃.
Verb (short for verb) is indefinite.
There is still scientific uncertainty in evaluating the impact of climate warming on human health. Mainly manifested in:
(1) Usually, climate change is accompanied by other environmental changes, and most diseases are caused by many reasons, influenced by heredity, physique, diet, living habits and environmental factors. It is difficult to separate the pathogenic effect of climatic factors from the comprehensive pathogenic factors.
(2) When predicting the impact of climate change on human health, it is difficult to accurately predict the possible changes in society, economy, population, science and technology, health care and other aspects in the next few decades. This brings great difficulties to study the impact of climate warming on human health.
(3) The response of human health to climate change can be caused by the endogenous characteristics of human beings, and it can also be caused by the relevant environment that human beings are sensitive to climate change. It is difficult to determine the sensitivity of human health to the impact of climate change.
(4) Simulating the influence of climate warming on human health, the existence of "normal value" itself has statistical changes; Some key values in the numerical model are approximately selected, and the structure of the model will inevitably be imperfect due to incomplete knowledge.
Countermeasures of intransitive verbs
As mentioned above, the negative impact of climate warming on human health is inevitable. For the sake of human health and sustainable development, the following countermeasures are suggested:
(1) It is suggested that governments at all levels and relevant departments further formulate and improve relevant policies, regulations and measures to reduce carbon dioxide emissions and increase carbon sinks, so as to slow down climate warming from the source and reduce its harm to human health.
(2) Facing the challenge of climate warming to human health, we have not only improved the existing level of public health infrastructure in health and epidemic prevention, but also adopted economic means; We should also take the same action from the aspects of ecosystem restoration and climate protection.
(3) Establish the cooperation mechanism between meteorology and health, environmental protection and other departments, and actively carry out comprehensive research on the occurrence law and pathological influence mechanism of climate warming on diseases; Strengthen the climate risk assessment and climate zoning research of major epidemics and infectious diseases. This paper mainly studies the relationship between the breeding, spread and outbreak of diseases and climate, and applies GIS technology to establish a database of health epidemic and climate change. Research on medical technology to deal with climate warming.
(four) to establish a comprehensive monitoring business system integrating meteorology, environment and epidemic situation system. Establish a guarantee system for human health meteorological services, strengthen the construction of medical meteorological departments, and further carry out medical meteorological forecasting.
(5) Make use of all available means to publicize and educate the society about climate warming and its threat to human health, and raise people's awareness of protecting the environment and climate. The government and people will work together to slow down climate warming and ensure human health.
(6) Climate warming is harmful to human health without borders, so international cooperation should be strengthened to enhance the ability to resist climate warming and benefit human health.