|Document ID:||Operational Directive OD 0265/10|
|Date of issue:||Friday, 22 January 2010|
|Status:||NO LONGER APPLICABLE|
|Description:||This Operational Directive outlines the health response to be activated to meet health disaster and emergency management requirements in response to a heatwave.|
|Category:||Disaster Preparedness and Management|
|Period of effect:||from 18 January 2010 to 18 January 2013|
|Review date:||18 January 2013|
|Authorised by:||Mr Kim Snowball, Acting Director General, Department of Health, 19-Jan-2010|
|Print version:||View print version|
This Policy only applies to Perth metropolitan area.
Extreme heat events are likely to become more common in WA as a result of climate change. The best estimate of average warming over Australia by 2030 is around 1.0 degree Celsius, with warming of around 0.7-0.9 degrees Celsius in coastal areas and 1-1.2 degrees Celsius inland. Associated with the warming is a projected major increase in the frequency of hot days and warm nights.
The increase in extreme heat events is projected to increase the number of heat related deaths. Mortality predictions sit at the extreme end of the impact scale but foreshadow the increase of minor heat-related health problems that will lead to increased hospitalisation, reduced quality of life and loss of productivity. In Northern France in 2003, unprecedented high day and night time temperatures for a period of three weeks resulted in 15,000 deaths in excess of those who would have died in the next few weeks or months due to illness or old age. There is strong evidence that these summer deaths are extra deaths and are the result of heat-related conditions. These can be direct effects of heat or indirect effects via exacerbation of underlying cardiovascular, respiratory or renal disease, and increases in homicides and suicides. The rise in mortality as a result of hot weather often occurs within one or two days of the temperature rising.
The heatwave in Victoria in January 2009, when maximum temperatures were 12-15 degrees above normal for much of the state, resulted in a 25% increase in total emergency cases attended by Ambulance Victoria and 374 excess deaths (a 62% increase in all cause mortality).
People gradually adapt to changing temperature. Thresholds vary across regions and risks to health appear to be greater earlier in the summer. There are indications that night time temperatures may be more important for impacts upon health than maximum day time temperatures.
The aim of this Operational Directive is to ensure that an efficient health response is activated to meet health disaster and emergency management requirements in response to a heatwave. The policy defines the roles and responsibilities of key Western Australian Department of Health agencies in mitigating the effects of a heatwave, especially on the most vulnerable people in the population.
A heatwave is defined as a period of abnormally and uncomfortably hot weather, which could impact on human health, community infrastructure and services.
A heatwave is not defined on the basis of temperature alone. The factors that contribute to a heatwave are:
Elevated night time temperatures during periods of hot weather in Australian cities are associated with increased morbidity and mortality. The lack of relief from the heat is particularly associated with increased mortality in the elderly.
The mean temperature is the average of the forecast daily maximum temperature and overnight minimum temperature. The method for calculating this temperature is outlined in Appendix 1. The heatwave threshold for the Perth metropolitan area is a mean temperature of 32 degrees Celsius.
COMPENSATED AND NON-COMPENSATED HEATWAVE
The ability of the population to mitigate the effects of extreme heat depends on the availability of functioning cooling systems.
In the event of a non-compensated heatwave, the activation of the policy will occur at lower temperatures and the content of the communication material will reflect the lack of power and the need to use alternative methods of cooling.
On confirmation of an imminent heatwave by the Bureau of Meteorology (BOM), the State Health Coordinator (SHC) is responsible for authorising the activation of the Heat Wave Response Plan. The On-call Duty Officer is responsible for monitoring alerts from BOM and communicating this information to the SHC.
HEAT WAVE RESPONSE PLAN
In the advent of a maximum temperature of 40 degrees Celsius or above in the Perth metropolitan area for one or more days, the heatwave response plan will be placed on alert. Non-metropolitan Public Health Units should determine the alert levels for their respective areas based on historical temperatures.
a. State Health Coordinator (SHC)
The SHC will:
In the advent of a predicted mean temperature of 32 degrees Celsius or greater for one or more days in the coming one to six days, the heatwave response plan will be put on standby. Non-metropolitan Public Health Units should determine the standby levels for their respective areas based on historical temperatures, cooling availability and acclimatisation.
The SHC will:
On the arrival of a predicted mean temperature of 32 degrees Celsius or greater for three or more days, the heatwave response plan will be put on response. Non-metropolitan Public Health Units should determine the response levels for their respective areas based on historical temperatures, cooling availability and acclimatisation.
The SHC will:
4. STAND DOWN
Once the heatwave has dissipated and hospitals have returned to normal functioning, the SHC will declare a stand down and contact the agencies activated.
IDENTIFICATION OF VULNERABLE GROUPS
The list of vulnerable groups is at Appendix 2. These groups should be considered in the development of media, monitoring and surveillance programs.
RELEASE OF INFORMATION
The DOH Public Affairs branch will work with the Disaster Preparedness and Management Unit (DPMU) to develop draft statements and guidelines prior to any heatwave.
The DOH Public Affairs branch will work with Local, State and Commonwealth government agencies, as well as non-government organisations, to coordinate the media response and release of advice to the public. This information should include:
MONITORING, SURVEILLANCE AND REPORTING
The HEOC will be responsible for coordinating the collection of data during a heatwave. This data should include ambulance call-outs, ED attendances, hospital admissions and ICU admissions.
In the event of a heatwave that requires activation of the plan, the Disaster Preparedness and Management Unit is to produce an annual summary report.
MONITORING AND REVIEW
The Senior Policy Officer, Disaster Preparedness and Management Unit, is responsible for the monitoring and review of this document on an annual basis.
CALCULATING THE MEAN TEMPERATURE5
The mean temperature is calculated from the forecast daily maximum (in this case, Wednesday) and the forecast overnight temperature, which is the daily minimum for the following day (in this case, Thursday).
Mean Calculation for Wednesday:
(40 + 26) /2 = 33º C
The threshold for Perth is 32º C, so mean threshold will be exceeded.
HEAT VULNERABLE GROUPS.
Mr Kim Snowball
This circular last updated: Friday, 22 January 2010 at 1:21pm