Health Implications of Drought
Drought poses many and far reaching health implications. Some drought-related health effects occur in the short-term and can be directly observed and measured. But the slow rise or chronic nature of drought also can result in longer term, indirect health implications that are not always easy to anticipate or monitor.
Drought can also cause long-term public health problems, including:
- Shortages of drinking water and poor quality drinking water
- Impacts on air quality, sanitation and hygiene, and food and nutrition
- More disease, such as West Nile Virus carried by mosquitoes breeding in stagnant water
More health implications related to drought.
Reduced stream and river flows can increase the concentration of pollutants in water and cause stagnation. Higher water temperatures in lakes and reservoirs lead to reduced oxygen levels. These levels can affect fish and other aquatic life and water quality.
Runoff from drought-related wildfires can carry extra sediment, ash, charcoal, and woody debris to surface waters, killing fish and other aquatic life by decreasing oxygen levels in the water. Many parts of the United States depend on groundwater as a primary source of water. Over time, reduced precipitation and increased evaporation of surface water mean that groundwater supplies are not replenished at a typical rate.
Drought can limit the growing season and create conditions that encourage insect and disease infestation in certain crops. Low crop yields can result in rising food prices and shortages, potentially leading to malnutrition.
Drought can also affect the health of livestock raised for food. During drought, livestock can become malnourished, diseased, and die.
The dusty, dry conditions and wildfires that often accompany drought can harm health. Fire and dry soil and vegetation increase the number of particulates that are suspended in the air, such as pollen, smoke, and fluorocarbons. These substances can irritate the bronchial passages and lungs, making chronic respiratory illnesses like asthma worse. This can also increase the risk for acute respiratory infections like bronchitis and bacterial pneumonia.
Other drought-related factors affect air quality, including the presence of airborne toxins originating from freshwater blooms of cyanobacteria. These toxins can become airborne and have been associated with lung irritation, which can lead to adverse health effects in certain populations.
Having water available for cleaning, sanitation, and hygiene reduces or controls many diseases. Drought conditions create the need to conserve water, but these conservation efforts should not get in the way of proper sanitation and hygiene.
Personal hygiene, cleaning, hand washing, and washing of fruits and vegetables can be done in a way that conserves water and also reduces health risks. Installing low-flow faucet aerators in businesses and homes is one example of how to reduce water consumption while maintaining hand washing and other healthy hygienic behaviors.
People who engage in water-related recreational activities during drought may be at increased risk for waterborne disease caused by bacteria, protozoa, and other contaminants such as chemicals and heavy metals. Exposure can occur through accidentally or intentionally swallowing water, direct contact of contaminants with mucous membranes, or breathing in contaminants.
Untreated surface water can be a health threat in drought conditions. In untreated surface waters, some pathogens, such as a type of amoeba (Naegleria fowleri), are more common during drought because low water levels may create warmer water temperatures that encourage their growth.
As the levels of surface waters used for boating, swimming, and fishing drop, the likelihood of injury increases. Low water levels in lakes can put people at risk for life-threatening injuries resulting from diving into shallow waters or striking objects that may not be immediately visible while boating. Low surface water levels can also expose potentially dangerous debris from the bottom of lakes, rivers, and ponds.
Increases in infectious disease can be a direct consequence of drought.
Viruses, protozoa, and bacteria can pollute both groundwater and surface water when rainfall decreases. People who get their drinking water from private wells may be at higher risk for drought-related infectious disease. Other groups also at increased risk include those who have underlying chronic conditions.
Acute respiratory and gastrointestinal illnesses are more easily spread from person to person when hand washing is compromised by a perceived or real lack of available water. During water shortages, the risk for infectious disease increases when hygiene is not maintained.
E. coli and Salmonella are examples of bacteria that during drought can more readily contaminate food and cause infectious disease. Food can serve as a vehicle for disease transmission during a drought because water shortages can cause farmers to use recycled water to irrigate their fields and process the food they grow. When used to grow crops, improperly treated water can cause a host of infectious diseases (such as those caused by toxin-producing E. coli and Salmonella), which can be life-threatening for people in high-risk groups. In addition, the likelihood of surface runoff, which can occur when rain fails to penetrate the dry and compacted soil that often accompanies drought, can cause the inadvertent contamination of crops.
Other infectious disease threats arise when drought leads to the contamination of surface waters and other types of water that are used for recreational purposes. When temperatures rise and rainfall declines, people are more likely to participate in water-related recreation. Persons exposed to contaminated recreational waters are more likely to become infected with pathogens that thrive in the shallow warm waters that exist during drought conditions.
Conditions associated with drought may negatively impact people who have certain chronic health conditions such as asthma and some immune disorders.
Drought-related changes in air quality, such as increased concentrations of air particulates and airborne toxins resulting from freshwater algal blooms, can irritate the eyes, lungs, and respiratory systems of persons with chronic respiratory conditions.
Changes in water quality, such as increased concentrations of contaminants, can threaten persons whose immune systems are compromised.
In periods of limited rainfall, both human and animal behavior can change in ways that increase the likelihood of other vectorborne diseases. For instance, during dry periods, wild animals are more likely to seek water in areas where humans live. These behaviors increase the likelihood of human contact with wildlife, the insects they host, and the diseases they carry.
Drought reduces the size of water bodies and causes them to become stagnant. This provides additional breeding grounds for certain types of mosquitoes (for example, Culex pipiens). Outbreaks of West Nile virus, which is transmitted to humans via mosquitoes, have occurred under such conditions. Inadequate water supply can cause people to collect rainwater. This can lead to collections of stagnant water that can become manmade mosquito breeding areas.