For the United Nations Environment Programme (^{UNDP, 2010}), the disaster risk assessment considers seven steps:

Descriptive measures

Rate, Proportion, Mean, Attributable Risk, Correlation Coefficient, and Analysis of Variance.

Basic information

Morbidity and mortality databases (2000-2014) from the Jalisco Ministry of Health (^{Secretaría de Salud Jalisco, 2015}); Data from the Population Census: Total Population 2000 to 2015, urban localities equal to or greater than 2,500 inhabitants of the state of Jalisco, from the National Institute of Statistics and Geography (^{INEGI, 2010}); Meteorological data from 1965 to 2013 ERIC III from the Mexican Institute of Water Technology - Ministry of the Environment and Natural Resources (^{IMTA-SEMARNAT, 2013}). Meteorological data from 1970 to 2014 from the Institute of Astronomy and Meteorology of the University of Guadalajara (^{IAM/UDG, 2015}); Atmospheric monitoring data from 2000 to 2014 from the Ministry of Environment and Territorial Development of the State of Jalisco (^{SEMADET, 2020}).

Evaluation criteria

For the meteorological data it was considered as a quality criterion that the station was located within the urban area and that it had continuous data in 80 % or more of the days of the study period. For mortality data, the causes were considered in the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision -CIE 10- (^{OPS, 2018}), avoiding those included in the “garbage code” list (^{Naghavi et al., 2010}), that is, with an identification of ill-defined, unspecific causes or those that cannot be considered as basic causes of death.

Reliability Criteria

With respect to the definition and association of variables, a review of institutional sources such as the World Health Organization (^{WHO, 2021}), the United Nations Environment Programme (^{UNEP, 2021}) and the Center for Disease Control and Prevention (^{CDC, 2019}) was considered; in addition to research journals with high visibility that address the issue of temperature, climate change and health: Environmental Health Perspectives and Epidemiology (Table 1).

Validity

The vulnerability assessment considered the methodological contributions of the World Health Organization, the United Nations Development Programme, the United Nations Environment Programme, the World Meteorological Organization, and the Social Studies Network on Disaster Prevention in Latin America (LA RED).

Hazard assessment

Analyzing the maximum temperature of 30 years (1970-1999) in the sites of greater concentration of the population of the state, it was observed that the monthly normal of maximum temperature presented its higher values in the months of April and May with greater probability of presence of temperatures of risk to the health, with data above 29 °C. The risk season has been extended in the period 2000-2015 from two to four months: March, April, May and June.

The years 2002 and 2003 presented the greatest positive anomaly of maximum temperatures above 3 °C, while 2004 registered the smallest value with a positive anomaly of 0.1 °C. The highest positive anomaly of maximum monthly temperature for the month of March was 4.8 °C in 2002; April 4.6 °C in 2001; 3.8 °C for May 2003 and 3.7 °C for June 2005. It is noteworthy that the highest temperature anomaly in 2002 and the lowest in 2004 was found in all the local weather stations with data that meet quality criteria located within urban areas.

For the daily extreme temperature evaluation, the two record years of positive maximum temperature anomaly (2002 and 2003) were analyzed, where the highest average correlation between maximum temperature and mortality from cardiovascular diseases was obtained at 36 °C (97^th percentile), with a correlation of 0.34, indicating that exposure to these temperatures determines an increase in mortality from this cause, by 11 %.

From 2000-2014, heat waves occurred in 87 % of the years analyzed; in 2004 and 2014 they did not occur. Of the years with heat waves, in 54 % of them the maximum temperature was less than 36 °C, being the years from 2006 to 2010, 2012 and 2013.

The greatest estimated risk occurred in 46 % of the years with heat waves with extreme temperatures of 36 °C or more. The year 2002 recorded two heat waves, one of 27 days (April 17 to May 13) and another of 7 days (May 20 to 26); followed by 2001 with a 24-day wave (April 1 to 24); 2003 with 23 days (May 1 to 23); 2011 with 20 days (May 12 to 31); 2000 with 15 days (April 17 to May 1) and 2005 with 11 days (June 1 to 11).

Exposure assessment and population at risk

Gender differences were found with respect to heat exposure and death from cardiovascular disease, with a higher relative risk for males (5.57) than females (4.91).

Vulnerability analysis

Jalisco has 70 895 hectares with predominant use of human settlements, in which 87 % of the state population is concentrated, 60.3 % resides in the metropolitan area of Guadalajara (Guadalajara, Zapopan, Tlaquepaque, Tonalá, El Salto, Tlajomulco de Zúñiga and Ixtlahuacán de los Membrillos).

Of all the locations analyzed, those referred to the Guadalajara metropolitan area are those that show critical conditions in all the vulnerability indicators, so in terms of this methodology the most vulnerable settlements could be considered.

Vulnerability in the high category is found in the following municipalities/indicator:

By high population density: Guadalajara, Zapopan, Tlaquepaque, Tlajomulco de Zúñiga, El Salto, Tonalá, Lagos de Moreno and Puerto Vallarta.

Children ≤5 years old: Guadalajara, Tlaquepaque, Zapopan, Tonalá, Puerto Vallarta and Tlajomulco de Zúñiga.

Adults ≥70 years old: Guadalajara, Zapopan, Lagos de Moreno, Tlaquepaque and Jalostotitlán.

Illiterate: Guadalajara, Zapopan, Tlaquepaque, Tonalá, Puerto Vallarta.

Houses without drinking water service: Tonalá, Zapopan, Tlaquepaque, El Salto.

Homes without electricity service: Tonalá, Zapopan, Tlaquepaque, Puerto Vallarta and La Barca.

Population without the benefit of health services: Guadalajara, Zapopan, Tlaquepaque, Tonalá, Puerto Vallarta and El Salto.

Poverty: Guadalajara, Zapopan, Tlaquepaque, Tlajomulco de Zúñiga, Tonalá, Puerto Vallarta and Lagos de Moreno.

The above confirms that the greatest vulnerability in Jalisco is presented in its most critical condition in the metropolitan municipalities, which coincides with the importance being given at a global level to generate better adaptation measures to face climate change and climate variability, prioritizing the cities, first because the greatest amount of population is concentrated in them; They exhibit growth dynamics without planning and evaluation of the impact of the risks to health and life that this generates, they show the greatest number of people without coverage of basic services and poverty, and the response capacities at the individual and institutional levels are not being sufficient to face the demands related to climate change.

Analysis of the loss of health in the exposed population

Mortality

Considering the annual mortality rate in Jalisco in the period of study (2000-2014), it can be noted that the years 2002 and 2003 are above the trend and that 2004 shows a considerable decrease. During this period, an increase in mortality rates was observed, from 46 to 51 deaths per 10,000 inhabitants.

Figure 1 confirms that the annual mortality rate was higher than the trend line in the three years with positive maximum temperature anomalies with values above 2.5 °C, while in the years with anomalies <1 °C, it was below the trend line. Given the trend scenarios of climate change where positive maximum temperature anomalies will be seen more frequently, it is expected that there will be an increase in mortality rates in Jalisco.

Figure 1 Annual mortality rate behavior per 10 000 inhabitants in Jalisco during 2000-2014. 

Morbidity

Determination of the health burden of climate-sensitive diseases or events, taking into account the locations most vulnerable to maximum temperature increases.

In Table 2 it is noticeable how the intestinal infections by other organisms and the poorly defined ones (A04- Other intestinal bacterial infections-; A08- Intestinal infections due to viruses (except rotavirus) and other specified organisms- and A09- Diarrhea and gastroenteritis of presumed infectious origin-.) follow a pattern where the highest medical consultations occur in years with positive maximum temperature anomaly, which is very different in years close to normal.

To confirm the statistical significance of this difference between abnormalities, analysis of variance (ANOVA) was performed for all health regions by studying the pattern of intestinal infections. The Region 13 - Guadalajara- resulted with the highest statistical significance, followed by the Region 11 -Tonalá-, also with significant differences.

The Guadalajara sanitary region presented an annual difference of 18,400 medical consultations for intestinal infections in years with positive anomaly >2.5 °C with respect to those that registered <1 °C (which represented more than 50 consultations per day), and the Tonalá region with a difference of 3,711 medical consultations for intestinal infections per year (on average 10 additional consultations per day) (Table 3).

It is important to consider that in the assessment of risk of disease burden, intestinal infections are related to exposure to contaminated water, this is important, because the years that had the greatest positive anomaly of maximum temperature, were also years with more intense rainfall which causes flooding. Furthermore, in the case of the Tonalá Region, it is one with the highest indexes of surface water contamination.

To separate the effect of both phenomena (temperature and intensity of rain), the ANOVA was calculated considering only the hot months, without rain (April-June), finding a statistical significance (ratio of variances: 20.83).

Even if there is no statistical significance to consider that climate change is influencing the increase of other diseases, it is important to continue with prevention and monitoring measures for some groups of diseases, for example, vector-borne diseases. Several studies have shown that mosquitoes are extremely sensitive vectors to climate change. In 2009, Guadalajara registered 4,045 confirmed cases of dengue, one of the highest in the country, in a period from May 10 to December 19, with most cases occurring between August 23 and September 12. In 2019, this phenomenon occurred again and according to data from the Ministry of Health, Jalisco topped the list nationally for dengue cases with 11,727 cases (incidence of 141/100,000 inhabitants) (^{Secretaría de Salud, 2020}). But perhaps most importantly, it is recognized that in temperatures higher than 13 °C mosquitoes hatch (^{Hopp & Foley, 2001}). This is important, if we consider that the minimum temperatures in Guadalajara have been increasing, there is less cold, which represents an increase of 63 days per year with activity of the mosquito vector Aedes aegypti and the risk of exposure of the population.

Identify risk reduction capacity

In Jalisco it is identified in a trend scenario, that the increase of temperature (Figure 2) and heat waves, will cause an increase in mortality and morbidity, particularly those sensitive to changes in climate, such as cardiovascular diseases, intestinal infections by other organisms and poorly defined. Likewise, it is expected that those caused by vectors such as dengue fever will increase, including an increase in scorpion stings.

Figure 2 Increase in minimum temperatures from the normal period 1970-1999 and average 2000-2014 in Guadalajara. 

One way to reduce the risk is by decreasing the exposure of the population to dangerous temperatures, increasing information and knowledge of the effects that heat and climate changes have on health, risk communication, improving health protection against heat and climate variability through changes in behavior, food, technologies, constructions, green infrastructure, consumption patterns, cooling modules, public water troughs, surveillance, monitoring and research of diseases that are aggravated and triggered by heat, since many countries have increased the capacity to prevent diseases and deaths through decision-making based on information and knowledge, a greater interest in preparing human resources professionals in the health sector and public policies for risk reduction in the population and vulnerable sectors.

Formulation or review of strategies and action plans to reduce losses

Under current conditions, it is considered that the health sector in Jalisco should prepare for emergencies that may occur in contexts of climate change, since there are precedents regarding some events related to vector diseases where the response capacity has been complicated by demand. Faced with critical increases in diseases, a rapid, organized and coordinated response is required from the health sector, in the surveillance and warning of those that present high sensitivity to heat or propagation, diagnosis, attention to medical consultations, emergencies and control of sensitive diseases, availability of medicines and infrastructure, and number of doctors, nurses and beds per inhabitant, professionalization and preparation of medical personnel to precise diagnosis of diseases and effects of heat, medical units, research centers and specialized laboratories, emergency planning of the sector and authorities, and early warning systems and risk communication strategies and for self-protection appropriate for the population. Reducing the risk of disasters requires a health sector that is prepared and committed to acting to prevent disease and anticipate deaths.

Jalisco agrees with the ^{IPCC (2012)}, that the maximum temperature is recognized as a reference of high confidence of climate change, so it should be considered as an indicator for monitoring the health sector.

The male gender presented greater health effects related to exposure to extreme temperature, which coincides with the report made by the CDC in the United States of America during 1999-2003 (^{CDC, 2006}) and ^{Bai et al. (2014)} for China during 2011-2013.

The largest human settlements in Jalisco were found to be the most vulnerable in the state because of the high number of inhabitants exposed to the danger of extreme maximum temperatures, considering the indicators referred to: 1. Population density, as identified by ^{Lavell (1996)}: the greater the number of people in a territory, the greater the damage possible in the presence of a hazard. 2. Children under 5 years old, also recognized by ^{Yaron & Niermeyer (2004)} as a vulnerable group in the face of rising temperatures and heat waves, pointing out that children lack thermoregulatory control, less sweating capacity and consequently the ability to dissipate heat, in addition to their limited ability to instinctively replace fluid loss or decrease their exercise in extreme heat. 3. Adults over 70 years of age in accordance with ^{Medina-Ramón et al. (2006)}, who mention that older people are more susceptible to temperature extremes with more marked effects on heat, which may be explained in part by a decrease in their ability to thermoregulate and to detect temperature changes in their bodies. 4. Illiteracy, also identified by ^{Bai et al. (2016)} as a component that increases vulnerability to death or illness on days with high temperatures. 5. Population without access to health services, Likewise, ^{Ebi et al. (2010)} have pointed out when referring to those with limited access to medical care as a vulnerable group in terms of health in the face of climate change impacts. 6. Poverty, confirmed by the (^{United Nations, 2009}) by pointing out that poor communities are the ones who face the greatest risk to climate-related disasters, have the greatest impacts and also the highest mortality. 7. Houses without drinking water service, similar to what was found by ^{Inostroza et al. (2016)} when they pointed out that access to drinking water is a variable that determines the capacity to adapt and vulnerability to heat, and that climate change adaptation measures in the most vulnerable areas should include improvements in the supply of drinking water. 8. Homes without electricity service, is confirmed by what ^{Jessel et al. (2019)} cited, who point out that energy insecurity in housing has serious implications for health, among which are the increase in morbidity and mortality rates of physical and mental illness during heat waves, in addition to not being able to implement adaptation measures such as having a refrigerator and air conditioning.

The findings on increased mortality from cardiovascular diseases related to increased maximum temperatures or prolonged periods of heat coincide with those reported by ^{Medina-Ramón et al. (2006)}, regarding a greater marginal increase in mortality and those reported by ^{Semenza et al. (1996)}, who refer that deaths from cardiovascular causes related to increased heat were also related to advanced age and pre-existing medical conditions. Therefore, future research should identify specific risk factors associated with these deaths.

With regard to morbidity from diarrhea and gastroenteritis of presumed infectious origin, the results found are consistent with research conducted on several continents. In Australia, ^{Hall et al. (2011)}, found that at 7 °C the average temperature increased the probability of gastroenteritis by 4.6 %. Additionally, ^{Lin et al. (2016)}, confirm in New York that for every degree Celsius increase in maximum temperature was significantly associated (0.7-0.96 %) with an increase in hospitalizations for gastrointestinal diseases. Finally, ^{Zhou et al. (2013)} identified in Shanghai that high temperatures were associated with an increased risk of diarrhea and gastroenteritis.

The Health and Climate Atlas published by the ^{World Health Organization in collaboration with the World Meteorological Organization (2012)} states that four infectious diseases are associated with climate change: malaria, diarrhea, meningitis and dengue fever. With respect to the last one, in Jalisco the temperature has increased, going from six months to the year as a period free of hatching of the mosquito transmitter of the dengue to only four months. The tendency presents us with a scenario where this control disappears and we have every day of the year temperatures with biological activity for this vector.

The level of progress made on the issue of climate change has allowed Jalisco to recognize the demands of the health sector in the face of temperature increases and heat waves. The factors that contribute to the vulnerability of urban human settlements must be prioritized in the design and implementation of adaptation strategies and actions.

Reducing the vulnerability of the Jalisco state urban human settlements must address critical aspects of development: poverty, illiteracy, deficiencies in health services, total coverage of water and energy services, (water and energy are necessary factors for temperature regulation and prevention of disease and death), since until progress is made, moving to other levels of attention to problems such as climate change will be more complex and efforts and results will continue to be limited.