Marine Pollution

 Wildfire

A wildfire, bushfire, wildland fire or rural fire is an unplanned, unwanted, uncontrolled fire in an area of combustible vegetation starting in rural areas and urban areas.Depending on the type of vegetation present, a wildfire can also be classified more specifically as a forest fire, brush fire, bushfire(in Australia), desert fire, grass fire, hill fire, peat fire, prairie fire, vegetation fire, or veld fire.Many organizations consider wildfire to mean an unplanned and unwanted fire,while wildland-fire is a broader term that includes prescribed fire as well as wildland fire use (WFU; these are also called monitored response fires).

Wildfires can be characterized in terms of the cause of ignition, their physical properties, the combustible material present, and the effect of weather on the fire.Wildfires can cause damage to property and human life, although naturally occurring wildfires may have beneficial effects on native vegetation, animals, and ecosystems that have evolved with fire. Wildfire behavior and severity result from a combination of factors such as available fuels, physical setting, and weather.Analyses of historical meteorological data and national fire records in western North America show the primacy of climate in driving large regional fires via wet periods that create substantial fuels, or drought and warming that extend conducive fire weather.

Causes

Natural

Leading natural causes of wildfires include:

• Dry climate
• Lightning
• Volcanic eruption

Human activities

The most common direct human causes of wildfire ignition include arson, discarded cigarettes, power-lines arcs (as detected by arc mapping ), and sparks from equipment.Ignition of wildland fires via contact with hot rifle-bullet fragments is also possible under the right conditions.Wildfires can also be started in communities experiencing shifting cultivation , where land is cleared quickly and farmed until the soil loses fertility, and slash and burn clearing.Forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned logging roads overgrown by vegetation may act as fire corridors. Annual grassland fires in southern Vietnam stem in part from the destruction of forested areas by US military herbicides, explosives, and mechanical land-clearing and -burning operations during the Vietnam war.

Prevention

Wildfire prevention refers to the preemptive methods aimed at reducing the risk of fires as well as lessening its severity and spread.Prevention techniques aim to manage air quality, maintain ecological balances, protect resources,and to affect future fires.North American firefighting policies permit naturally caused fires to burn to maintain their ecological role, so long as the risks of escape into high-value areas are mitigated.However, prevention policies must consider the role that humans play in wildfires, since, for example, 95% of forest fires in Europe are related to human involvement.Sources of human-caused fire may include arson, accidental ignition, or the uncontrolled use of fire in land-clearing and agriculture such as the slash-and-burn farming in Southeast Asia.

Strategies for wildfire prevention, detection, control and suppression have varied over the years.One common and inexpensive technique to reduce the risk of uncontrolled wildfires is controlled burning: intentionally igniting smaller less-intense fires to minimize the amount of flammable material available for a potential wildfire.Vegetation may be burned periodically to limit the accumulation of plants and other debris that may serve as fuel, while also maintaining high species diversit. Jan Van Wagtendonk, a biologist at the Yellowstone Field Station, claims that Wildfire itself is "the most effective treatment for reducing a fire's rate of spread, fireline intensity, flame length, and heat per unit of area." While other people claim that controlled burns and a policy of allowing some wildfires to burn is the cheapest method and an ecologically appropriate policy for many forests, they tend not to take into account the economic value of resources that are consumed by the fire, especially merchantable timber. Some studies conclude that while fuels may also be removed by logging, such thinning treatments may not be effective at reducing fire severity under extreme weather conditions.

Health effects

Wildfire smoke contains particulate matter that may have adverse effects upon the human respiratory system. Evidence of the health effects of wildfire smoke should be relayed to the public so that exposure may be limited. Evidence of health effects can also be used to influence policy to promote positive health outcomes.

Smaller particulate moves further into the respiratory system creating issues deep into the lungs and the bloodstream.In asthma patients, PM_2.5 causes inflammation but also increases oxidative stress in the epithelial cells. These particulates also cause apoptosis and autophagy in lung epithelial cells. Both processes cause the cells to be damaged and impacts the cell function. This damage impacts those with respiratory conditions such as asthma where the lung tissues and function are already compromised.The third PM type is ultra-fine PM (UFP). UFP can enter the bloodstream like PM_2.5 however studies show that it works into the blood much quicker. The inflammation and epithelial damage done by UFP has also shown to be much more severe.PM_2.5 is of the largest concern in regards to wildfire. This is particularly hazardous to the very young, elderly and those with chronic conditions such as asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis and cardiovascular conditions. The illnesses most commonly with exposure to the fine particles from wildfire smoke are bronchitis, exacerbation of asthma or COPD, and pneumonia. Symptoms of these complications include wheezing and shortness of breath and cardiovascular symptoms include chest pain, rapid heart rate and fatigue.