Επιστημονικά Θέματα

1* Forest fires consist an environmental disaster with global consequences (ecological, economical, medical). More specifically, large scale forest fires, such as the ones which take place in various places of the world (e.g. Borneo, Sumatra in 1997-98), usually contribute to a significant percentage of global air pollution, threatening not only the populations in the vicinity of the fire front, but the populations on a global basis. More specifically, forest fire smoke can have short and long term health impacts, due to the physical and chemical properties of its components.

Forest fire smoke can be considered as a two phase mixture, consisting of both gaseous and particulate components. Over 150 chemical species have been detected in the smoke of forest fuel combustion and pyrolysis experiments, including permanent gases such as CO, CO2, NOx , SOx , Volatile Organic Compounds (VOCs) such as hydrocarbons, aldehydes, substituted furans, carboxylic acids, Benzene, Toluene, Xylene (BTX), Semi Volatile Organic Compounds (SVOCs) (e.g. Polyaromatic Hydrocarbons); particles are also produced that usually contain Trace Elements such as Na, Mg, Ni, Cu, Pb, Fe, Mn, etc. Many of those species can have acute or long term health implications on the exposed populations, according to exposure limits given by official Organizations for health protection such as OSHA (Occupational Safety and Health Administration), NIOSH (National Institute for Occupational Safety) and ACGHI (American Conference of Governmental Industrial Hygienists).

More broadly, it should be noticed that in real forest fires the chemical species will be greater in number and quantity than those determined in experimental scale. In addition, the type and size of the species that are formed can have significant health impacts. Generally speaking, the physical (e.g. shape of particles) and chemical properties (e.g. acidity/alkalinity-pH) of the forest fire smoke components have to be studied thoroughly to determine the possible health consequences.

Forest fires impact includes health and safety issues, environmental issues and natural hazards. In case of a big fire incident it is very important for the crisis managers to estimate the severity of the situation and take fast and effective decisions, so as to protect the fire personnel and the civilians. For example, if a situation will be considered as an emergency one, then perhaps there will be the necessity of taking special measures, such as to wear masks or to evacuate an inhabited area, which is very close to the fire. According to all these, the operational value of an effective decision chart for crisis managers is very significant.

A large forest fire is considered as a crisis situation, especially when it expands and put in fire rural /urban constructions, rural fields or waste disposals. In these cases, the smoke produced might be the additive or the synergistic result of the pyrolysis and combustion of all the possible materials and fuels burned. If a forest fire spreads for example to a landfill nearby the forest, then possible organic products can be PCDDs, PCDFs and PCBs, evolved due to the pyrolysis and combustion of different materials and fuels of the landfill.

Consequently, for a crisis manager it is critical to reconsider the perception about the chemical synthesis of the resulted smoke; combustion and pyrolysis of other materials and fuels (e.g. plastic, wood, paint, or agricultural crops), depending on the pathway of the flame-front should be taken into consideration.

Generally, the smoke produced from biomass burning consists of various components (permanent gases, VOCs, SVOCs, particulate matter) with different physical (e.g. physical state, size and shape of particles) and chemical (e.g. alkalinity/acidity, vapour pressure) properties that can related to health impacts. The most hazardous permanent gas produced in a forest fire is considered the CO. The NIOSH Recommended Exposure Limit TWA (REL Time-Weighted over 10-hour work-shift) and OSHA Permissible Exposure Limit for General Industry TWA (PEL Time-Weighted over 8-hour work-shift) is 35 and 50 ppm respectively. (2) CO concentration levels, estimated during a forest fire in USA, ranged between 4 and 23 ppm. Also, during field measurements that took place in a forest fire nearby an urban area, the CO was determined at different sites close to the flame front. Specifically, the median concentration, measured in a time frame of one hour, ranged between 1 ppm and 8 ppm among the sites. Though, under very smoky conditions CO concentration locally exceeded the value of 40 ppm. However, until now there are no systematic measurements of CO in the fire front during a fire incident.

2* A protocol was designed to study the health effects of CO and irritants on forest fire fighters, taking into consideration that a small percentage may experience adverse health effects due to individual susceptibility, a pre-existing medical condition and/or hypersensitivity (allergy). Also, some substances are absorbed by direct contact with skin and mucous membranes and thus, potentially increase the overall exposure. In unusual work schedule, such as in case of a forest fire, the working conditions for the fire fighters are heavy. Using a work-shift length of 12 hours the recommended CO exposure limit for forest fire fighters is calculated 17 ppm, by using the pharmacokinetic model (CFK equation) that it had been used in developing the NIOSH REL. 2* The initial symptoms of CO poisoning may include headache, diziness, drowsiness and nausea. Reasearch has been shown that there is a correlation between the concentration of inhaled CO and the %COHb (Carboxyhemoglobin) in blood. A normal percentage of COHb in blood is 1% for non-smokers and 2-10% for smokers or residents of big cities. Loss of consciousness occurs at about 50% COHb level and death can occur at levels of 70%.The NIOSH REL of 35 ppm is designed to protect workers from health effects associated with COHb levels in excess of 5%. Regarding the forest fire fighters, the percentage of 5% COHb could be reached with CO exposure of 17 ppm.

1* It should be emphasized that traditional exposure limits for CO may not be protective for the working environment encountered by forest fire fighters. This information is important to properly protect fire fighters from the deleterious health effects associated with CO intoxication.

CO2 is another abundant product of forest fuel combustion. Typically, the outdoor, ambient concentration of CO2 is approximately 350 ppm. (2) During fire incidents it was found that CO2 exposures were approximately 3 times higher than the normal background concentration. Though, according to Table 1, CO2 was below the applicable occupational exposure limits, as long as the NIOSH REL (Time-Weighted over 10-hour work-shift ) and OSHA PEL (Time-Weighted over 8-hour work-shift) are 5.000 ppm and 10.000 ppm, respectively.

3* In case of using commercial forest fire retardants, such as a mixture of ammonium phosphate and ammonium sulfate, NH3 exceeded the ACGHI recommended level of 35 ppm in the vicinity of the fire.*4,*5 The effect of fire retardants on the pyrolysis products of forest fuels, such as cellulose and pine needles, has been studied in lab scale. Broadly speaking, (NH4) *2 HPO4 and (NH4) (2) HSO4 used as forest fire retardants produce an acid (phosphoric or sulfuric) prior to the flaming temperatures, which favor the dehydration process leading to increased quantities of char, water vapor and CO2 and reduced volatile products.

*6 Forest fire smoke is also consisted of Volatile Organic Compounds (VOCs) such as hydrocarbons, (alkenes, alkynes), aldehydes (acetaldehyde, formaldehyde, furfural, acrolein), substituted furans, phenol, carboxylic acids, BTX (Benzene, Toluene, Xylene), alkyl-benzenes that can have a number of health impacts. *7 The on-line monitoring of the fire- front emissions from pine needles combustion in lab experiments, resulted in maximum benzene and toluene concentrations of 1050 and 2050 ppm respectively. The combustion considered as of low oxygen content, a scenario which usually occurs in real forest fires (smouldering fire). *8 Benzene, toluene, and xylene were also measured at a distance of 3,5 km, 5 km and 10 km from the fire front of a large-scale forest fire and the concentrations in µg/ m3 for each of these compounds ranged between 0.4 -24.8, 0.3-15.5 and 3.7-28.7, respectively. *1 Though, there are no strong correlations evident between VOC levels and the incidence of active forest fires. While biomass combustion does lead to emission of BTX, their levels may have been overwhelmed by those from fossil fuel sources. According to Table 1, the NIOSH REL and OSHA PEL for benzene are 0,1 ppm and 1 ppm, for toluene are 100ppm and 200 ppm and for xylene 100 ppm and 100 ppm respectively.

Forest fires also produce a large number of organic compounds, which are partitioned between the gaseous and liquid or solid phase at ambient temperatures, so called semi-volatile organic compounds (SVOCs). PAHs (Polycyclic aromatic hydrocarbons) are among those SVOCs produced. They are hazardous compounds because many of its members are carcinogenic. PAHs can be condensed or absorbed onto the surface of fine particles. *9 Benzo (a) pyren [BaP], a PAH known for its carcinogenic properties, occur in most combustion emissions and is commonly used as indicator for PAHs. In urban areas, motor vehicles are the major source of PAHs in atmosphere, followed by residential wood/ (char)-coal combustion and industrial production processes. In medium polluted areas in European Countries the annual average [BaP]- level estimated 5-12 ng/m3 and at locations close to traffic, coal heating or industrial areas, the daily average BaP- concentration ranged between 4-69 ng / m3(max. 300 ng/m3). *9 According to literature, PAHs concentration decreases with the distance from the forest fire due to photochemical degradation processes. The OSHA has established a legally enforceable limit of 200 mg /m3 of all PAHs.

*10 Forest fire smoke is also consisted of particulate matter with significant contribution to health implications of the exposed populations, by damaging respiratory system. *11 OSHA standards allow workers to be exposed to 5.000 ug/m3 of respirable particles averaged over 8-hour shift, 5 days per week. The allowable exposures rely on the assumption that workers will spend 16-hours per day breathing clean air to allow them recover from exposures experienced at work. Obviously, this is not always the case in a fire situation where firefighters work shifts as long as 16 hours and spend any free hours at fire camps that are often smoky. (2) Since a large portion of the Total Particulate Matter (TPM) exposure is a product of combustion of the surrounding vegetation, possibly containing carcinogenic and /or otherwise substances (e.g. absorbed PAHs, *12 levoglucosan, retene, vanillin), neither OSHA PEL nor ACGHI TLV may be appropriate evaluation criteria.

*6,*8 The most hazardous particles are the very small and respirable, such as PM10 and PM2,5, due to their enhanced effect on the lungs. Particles less than 10 micrometers in diameter tend to pose the greatest health concern because they can be inhaled into and accumulate in the respiratory system. *9 PAHs can condense or be absorbed onto the surface of fine particles, as well as elements such as S, Cl, K, Na, Mg, Fe, Cu, Zn, Pb and others, so that they can become more harmful matrixes. *2, *6 There is evidence that fine particles (PM2,5 , PM1 ) can have epidemiological effects and that exposure to fine particles is associated with several serious health effects, including premature death. This does not mean that coarse particles like PM10 could be considered as harmless, in fact they can aggravate respiratory conditions such as asthma. The ACGIH TLV-TWA 24-h for PM10 and PM2.5 are 150 µg/m3 and 65µg/m3 respectively. In field experiments during a forest fire nearby an urban area, PM2.5 median for 1 hour was 335 µg/ m3 and PM10 median for 1- hour was 1.300 µg/m3, though in very smoky conditions very close to the fire front the PM2.5 median for 30 sec was 6.865 µg/ m3.

*11 Generally, exposure to air pollutants (permanent gases, VOCs, SVOCs, Particulates) in significant concentrations can increase health risks. The air pollutants of greatest concern are those that cause serious health problems or affect many people, for example in the case of a large scale forest fire nearby an urban or rural area. Health problems can include respiratory irritation, nervous system problems and even cancer in some cases. There are some acute symptoms after a person inhales smoke, such as watery eyes or cough, but other health problems may be more serious and appear many months or years after a person's first exposure. For the fire-fighters, the continuous exposure for many years in such heavy conditions of smoke can become very hazardous, as well as for the exposed populations which could suffer from long-term epidemiological effects e.g asthma. So, emphasis should be given on the proper operational measures that should be taken under severe smoky conditions, like in case of a large-scale forest fire, where the emergency plans for risk management should be the most effective.

It is quite often the forest fire to expand to rural /urban areas, landfills etc. Therefore, forest fire smoke could be considered as the addition or the synergism of the smoke produced due to the pyrolysis/combustion of construction materials, fertilizers, pesticides and waste disposals. As a result, the smoke produced becomes more complicated and possibly more hazardous, due to its composition. In order to support decision making in a forest fire, a road-map has been developed, which includes different scenarios that could occur in case of a forest fire (Table 2).These scenarios include the expansion of a forest fire to rural fields, which will cause combustion of pesticides or fertilizers, to rural or urban constructions, which will cause pyrolysis and combustion of structurally materials, i.e. pulverized cement contained in the smoke produced, or to waste disposal and illegal waste disposal, which will cause waste incineration. The scenarios also include the combustion of chemically pretreated forest fuel with retardants, so as to prevent the fire spread (ground application) or to suppress the fire during the fire incident (aerial application). Heavy environments such as those of urban or industrial areas, could contribute a significant percentage of pollution in case the forest fire smoke plume reached them, and for that reason they are included as scenarios of the road-map.

In the road-map, the expected organic and inorganic products, due to the combustion or pyrolysis of each fuel type (scenarios 1-5) or due to the existed chemical species in the atmosphere (scenarios 6-7), are presented. They are also presented the type of the generated liquid –solid phase (i.e. soot, tars, particles), the size, the chemical composition, the physical and chemical properties and also the meteorological data and operational information that have been found in literature.

It should be emphasized that filling in the details of this road map (Table 2) needs further experimentation and field experiments. Consequently, the proposed road map is considered as a first version and more elaboration is needed.

Monitoring the type and levels of forest fire smoke components, needs instrumentation, methods and procedures of field analysis. Field chemical analysis and technology is using mobile and portable instruments for on-site analysis. Field analysis is based on chemical measurements in time and space, which make it the appropriate tool for on-line monitoring the air quality during a forest fire. It also consists of procedures which make it possible to integrate those methods in operational procedures. Field analysis by using sensors, particle analyzers and various methods, such as Gas Chromatography – Mass Spectrometry, can provide with instrumentation of different complexity. A number of these instruments are automated and can be used directly from operational personnel near the fire front and from other civil protection services, for measuring air quality.

Τable 1. Permissible exposure limits according to various organizations for specific compounds and particulates

Table 2. Air quality in forest fires. Decision chart for crisis managers

Summer of 2007 was one of the worst for South Europe regarding forest fires. Especially for Greece, the total area burned until the 31st of August 2007 was 269.114 ha; 11.2% of it was on NATURA 2000 sites (Source: EFFIS). These fires were devastating with high death toll and environmental, health, social and economic impacts.

Some of the largest forest fires in Greece occurred in Peloponnese, between the 24th and 31st of August 2007. In order to better record these fires, a data file has been prepared by collecting geographical, vegetation and meteorological data, as well as data on health, infrastructure and environmental impacts and also information regarding fire suppressing resources and means. Generally, quality, accuracy and broad types of data are the cornerstones for prevention, for developing guidelines, as well as for improving tactics and enhancing strategies. Compilation of multi-source data can be used for documenting a big forest fire and for providing a prototype data file.

The above data file is the work of a number of specialists, experts and service people, engaged in the real events and is thoroughly presented in Forest Fire Net Volume 5 (FFNet 5), a publication of the European Center for Forest Fires. The article presented here is a part of this data file, focusing on the health impacts of Forest fires in Peloponnese, recorded for the period 24-31st of August 2007 (a case study).#

Forest fires and the resultant smoke can cause a number of health impacts on the exposed population and the fire-fighters. Those impacts are related with factors, such as the toxicity of forest fire smoke components, the characteristics of the smoke exposure, as well as the vulnerability of the exposed population. In general, the forest fire smoke is consisted of substances that can be respiratory irritants, such as aldehydes (e.g. acroleine), asphyxiants (e.g. carbon monoxide) and carcinogens (e.g. benzene, benzo[a]pyrene). Particles are also considered hazardous components of the forest fire smoke.

Generally, the fine particles, such as nanoparticles (with diameter less than 100nm) and respirable particles (with diameter between 0.1 and 10 μm) are considered more aggressive compared to the inhalable particles (with diameter between 10 to 20 μm). This is due to their small size that allows them to penetrate deeply the lungs. Health impacts due to smoke exposure are classified as acute, short-term and long-term, depending on the time duration that is needed for symptoms to appear.

2.1 Short-term health impacts

Irritation of eyes and nose, cough or acute respiratory infection are indicative short-term health impacts due to smoke exposure.

In Table 1, the number of admissions to medical centers and hospitals of Peloponnese for the time period between the 17th of August 2007 and the 10th of September 2007 are presented. Diagnosis was classified accordingly. Two sensitive groups of population (children, pregnant women) have been summed up and are presented in one column. The column referred as “other” includes the cases diagnosed with fractures, fever e.t.c. The number of deaths is also given.

The data presented have been recorded by 19 medical centers and hospitals of Peloponnese in Tripoli, Krestena, Megalopoli, Tropaia, Pyrgos, Gastouni, Ancient Olympia, Blaxioti, Areopoli, Kastori, Gutheio, Amaliada, Kalamata, Meligala, Kuparissia, Patra, Varda, Andritsaina, Dimitsana for the period 17th of August until the 10th of September 2007 (Source: Ministry of Health).

It can be observed that the number of admissions registered for the time period 24-31 of August 2007 was significantly increased in comparison with the relevant numbers before the 24th and after the 31st of August, a fact that can be related to the forest fires that occurred during that period.

In Fig. 1, the profile of the number of admissions to hospitals and medical centers of Peloponnese per category of symptoms, as presented in Table 1, is shown, emphasizing on the period 24-31 of August 2007.

Fig. 1. Profile of the number of admissions and number of deaths according to 19 hospitals and medical centers of Peloponnese 17/8-10/9/2007.

Table 1. Number and causes of admissions to 19 hospitals and medical centers of Peloponnese 17/8-10/9/2007.

2.2 Long-term health impacts

Pulmonary or chest diseases, asthma, cardiac problems or carcinogenicity, can be a number of long-term health implications that may appear after a significant time than the exposure happened. Generally, the time duration of the exposure to hazardous substances can have various health impacts. Acute exposure is usually less than 24-h, short-term exposure lasts usually one week, sub-chronic lasts about the 10% of someone’s life, whereas chronic exposure consists a significant time duration, over 10% of human life.

Forest fire-fighters are a group that is more at risk to have long-term health impacts, due to the frequency and duration of their exposure to forest fire smoke. In contrast, long-term health implications on populations that are not exposed frequently to forest fire smoke are usually limited. However, long-term health impacts can be significant for the sensitive groups of population, such as people with pre-existing respiratory problems, asthma, cardiac problems, as well as the elderly, children, infants, pregnant women and smokers. The use of effective personal protective equipment and possible evacuation of population are some of the measures that can be applied for copying with forest fire smoke impacts.

2.3 Deaths and toxicological data

The death toll in summer 2007 due to the devastating forest fires in Greece was 68. Generally, severe burns, as well as inhalation of significant quantities of toxic compounds are potential causes of death. According to the results of the toxicological analysis for a total number of 43 cases that were examined by the Forensic Medical Service of Patra, it was found that 22 were caused due to total fire burns, 17 due to various degrees of burns, 3 due to asphyxia by smoke inhalation and one due to coronary disease. In addition, 14 more cases have been examined by the Forensic Medical Service of Nafplion and 4 by the Department of Forensic Medicine and Toxicology, School of Medicine of the University of Athens, for which the main cause of death was also total burns.

Collection of geographical, meteorological and vegetation data, as well as of data regarding the resources used for suppressing the fires, and of data relatively to the impacts on health, the environment and infrastructures can be used as a platform for documenting future big forest fires.

Generally, documentation of different types of data can be used for optimizing prevention and copying with forest fires and their impacts. Data files can contribute to better organizing and managing the information regarding big forest fire events.

The following types of data are proposed to be included in a forest fire disaster file:

1. Geographical data

• map of the area
• coordinates of the area
• elevation

2. Vegetation data

• area burned by land cover type (forest, agriculture, artificial surfaces)
• areas burned per prefecture

3. Meteorological data

• temperature (daily average, minimum and maximum values)
• relative humidity (daily average values)
• wind speed (daily average and maximum values)

4. Resources used for suppressing the fires

• Aerial means (national and international)
• Ground means (national and international)
• Personnel (national and international)

5. Health Impacts

• Short-term health impacts due to smoke exposure and fire burnings (number of admissions to hospitals and medical centers)
• Long-term health impacts due to smoke exposure (epidemiological studies), especially for sensitive groups of population and the fire-fighters
• Number of deaths and toxicological data (cause of deaths)

6. Impacts on houses and infrastructures

• Total number of structural damages per prefecture
• Type of structural damage (total or partial) of the affected houses and public infrastructures

7. Environmental impacts

• Field chemical analysis data by on-line monitoring of air quality during a forest fire
• Field chemical analysis data by monitoring quality of soil and water