FSAWWA Speaking Out—Emilie Moore

Health Nexus: Water Consumption, Humidity, and Extreme Heat

Emilie Moore, P.E., PMP, ENV SP

Chair, FSAWWA

Water is our body’s principal chemical component and makes up approximately 50 to 70 percent of our body weight.

The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake (including fluids from water, other beverages, and food) is: S 92 ounces (11.5 cups) for women S 124 ounces (15.5 cups) for men

During 2015-2018, children and adolescents in the United States drank an average of 23 ounces of plain water daily and U.S. adults drank an average of 44 ounces of plain water daily, per a Centers for Disease Control and Prevention (CDC) water consumption study.

This study indicates that plain water intake is significantly lower in these categories: S Younger children S Non-Hispanic Black children or Hispanic children S Youth in lower-income households S Youth whose head of household has less than a high school education S Youth who are underweight or normal weight, based on calculated body mass index (BMI) S Older adults S Non-Hispanic Black adults S Adults with lower income S Adults with less than a college education S Adults who are underweight or normal weight, based on calculated BMI (source: www.cdc.gov/nutrition/data-statistics/ plain-water-the-healthier-choice.html)

Additionally per the CDC, when working in the heat, people should drink 8 ounces of water every 15 to 20 minutes, which is up to 32 ounces of water per hour. The CDC also states that drinking at shorter intervals is more effective than drinking large amounts infrequently. Additionally, it’s advised to not drink more than 48 ounces per hour, as too much water can cause a medical emergency because the concentration of salt in the blood becomes too low (hyponatremia).

Water Consumption Benefits

The Harvard Medical School notes that the benefits of water to proper body function include: S Carrying nutrients and oxygen to cells S Flushing bacteria from the bladder S Aiding digestion S Maintaining electrolyte balance S Normalizing blood pressure S Regulating body temperature S Protecting organs and tissues S Preventing constipation S Cushioning joints

Water consumption makes up for the body’s water losses through urine, via the skin, and respiration.

High humidity makes us feel hotter and uncomfortable, but it also increases our core temperature, causing our bodies to compensate by working harder to cool them down. When sweating does not work to cool us down and our bodies continue to heat up, it could result in overheating or heat exhaustion. This can lead to dehydration, chemical imbalances within the body, or even death. Dehydration depletes the body of water needed for sweating and thickens the blood, resulting in increased pressure to pump the blood throughout the body and straining the heart and blood vessels.

To prevent heat illness, there needs to be a balance between heat load on the body (heat produced internally by the body and gained from external sources) and heat released from the body to allow it to cool. Florida’s humid subtropical climate can stress the body because it has trouble removing heat when sweat does not evaporate readily.

Heat index, also known as the apparent temperature, is a measure of how hot it really feels to the human body with relative humidity factored in with the actual air temperature, according to the National Oceanic and Atmospheric Administration (NOAA), as shown in Figure 1.

Potential heat index impacts to our bodies include: S 80-90°F – Caution: Fatigue possible with prolonged exposure and/or physical activity S 90-103°F – Extreme Caution: Heat stroke, heat cramps, or heat exhaustion possible with prolonged exposure and/or physical activity S 103-124°F – Danger: Heat cramps or heat exhaustion likely, and heat stroke possible with prolonged exposure and/or physical activity S 125°F or higher – Extreme Danger: Heat stroke highly likely

The heat index values in Figure 1 are for shady locations. If you are exposed to direct sunlight, the heat index value can be increased by up to 15°F.

The Occupational Safety and Health Administration (OSHA) requires employers to provide water on the jobsite. Its recommendations related to water consumption and heat index include: S Heat Index <91°F: An employer must provide drinking water S Heat Index 91 to 103°F: An employer must remind workers to drink water often (about 4 cups/hour) S Heat Index 103 to 115°F: An employer must actively encourage workers to drink plenty of water (about 4 cups/hour) S Heat Index >115°F: An employer must establish a water-drinking schedule (about 4 cups/hour)

The Code of Federal Regulations, Title 29 – Labor, outlines the duties of an employer, including these that are related to potable water access in Part 1915, Subpart F (General Working Conditions): S 1915.88(b)(1): The employer shall provide potable water for all employee health

and personal needs and ensure that only potable water is used for these purposes. S 1915.88(b)(2): The employer shall provide potable drinking water in amounts that are adequate to meet the health and personal needs of each employee. S 1915.88(b)(3): The employer shall dispense drinking water from a fountain, a covered container with single-use drinking cups stored in a sanitary receptable, or single-use bottles. The employer shall prohibit the use of shared drinking cups, dippers, and water bottles.

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Potable water is defined in Part 1915, Subpart F, as “water that meets the standards for drinking purposes of the state or local authority having jurisdiction, or water that meets the quality standards prescribed by the U.S. Environmental Protection Agency’s National Primary Water Regulations (40 CFR, Part 141).”

These regulations clearly outline that an employer is obligated to provide water on the jobsite and to ensure that potable water is readily available in sufficient quantities and consumed by employees.

An existing heat illness prevention campaign from OSHA is currently developing formal heat regulations to protect indoor and outdoor workers from hazardous heat (Figure 2) and an advance notice of proposed rulemaking was issued in October 2021. It’s anticipated that the regulations will focus on protecting workers in environments where the heat index is greater than 80°F.

Currently, the Division of Occupational Safety and Health in California (Cal/OSHA) requires that when air temperature in the workplace exceeds 80°F, shade structures must be erected if no other shade is readily available.

Considering that OSHA is proposing workplace hazardous heat regulations, it seems that current water treatment facilities with ventilated-only buildings may require climatecontrolled environments in the future.

Figure 3. National competition logo. (source: EPA)

Heat’s Physiological Impacts

When the air temperature gest hotter than skin temperature (typically 97-99°F), or if sweat does not evaporate, the body starts to gain heat and its core temperature rises. If body temperature rise is unabated, people may experience heat-related illnesses.

People at greater risk to the health effects of heat include: S Infants and children, as they lose fluid more quickly than adults and rely on caretakers to help keep them cool (U.S. Environmental

Protection Agency [EPA]). S People taking certain medications. S Older adults, as they produce less sweat per gland, blood vessels change as people age, and it may be more difficult for blood to get pumped to the skin to help cool them down.

Heat stroke can occur with the body’s core temperature reaches at least 104°F and can lead to organ failure, brain damage, and potential death. Cognitive impairment can occur when a person is experiencing heatstroke. Older adults and children are most vulnerable to heat stroke.

A 2022 published study examined the association between higher warm-season temperatures and the number of mental health-related emergency department (ED) visits by U.S. adults with health insurance (commercial health insurance or Medicare Advantage). The researchers evaluated approximately 3.5 million ED visits and found that higher warm-season temperatures increase the risk of emergency department visits for mental-health conditions, including substance use disorder, anxiety disorders, schizophrenia, self-harm, and childhoodonset behavioral disorders (Nori-Sarma, Amruta; Sun, Shengzhi; Sun, Yuantong; et al. “Association Between Ambient Heat and Risk of Emergency Department Visits for Mental Health Among U.S. Adults, 2010 to 2019.” JAMA Psychiatry, Feb. 23, 2022).

Rising body temperatures cause people to breathe harder. This is dangerous for people with respiratory-compromised systems from conditions such as asthma and chronic obstructive pulmonary disease (COPD). Air pollution and pollen may accompany high heat and can make breathing more difficult.

High temperatures may strain the heart and lead to heart attacks. When our body temperature rises, our heart rate rises and the

Figure 4. Extreme heat days in the United States in 2050. (source: NOAA)

heart works harder to pump blood near the skin to get rid of the heat. About a quarter of heatrelated deaths are caused by a combination of heat and cardiovascular disease (EPA).

Millions of workers around the world are exposed to chronic heat stress and recurrent dehydration that may increase their risk for chronic kidney disease (CKD) and ultimately kidney failure. (Nerbass, Fabiana B.; PecoitsFilho, Roberto; Clark, William F., et al. “Occupational Heat Stress and Kidney Health: From Farms to Factories.” Kidney International Reports, 2017)

When the body heats up, kidneys will decrease their outflow of urine as blood flow decreases away from internal organs to the skin, and body fluid is secreted as sweat. There is increasing evidence that heat exposure greater than 104°F can cause daily subclinical acute kidney injury (ischemia, temperature-induced oxidative stress, and decreasing intracellular energy stores), which may cumulatively impair kidney function and result in CKD, either directly or by exacerbating renal insults caused by other environmental exposures—or both. (Sorensen, Cecilia; Garcia-Trabanino, Ramon; :A New Era of Climate Medicine – Addressing Heat-Triggered Renal Disease.” The New England Journal of Medicine, Aug. 22, 2019)

Extreme Heat Risks Initiatives

The EPA and its cosponsors (NOAA, Federal Emergency Management Agency, U.S. Department of Health and Human Services, The Atlantic Council, Georgetown Climate Center, Groundwork USA, and National Association of County and City Health Officials) launched the Let’s Talk About Heat Challenge (www.epa. gov/innovation/lets-talk-about-heat-challenge), a national competition (Figure 3) to identify innovative and effective communication strategies that inform people of the risks of extreme heat and identify ways to keep safe during the hottest days. Extreme heat is linked to an increased risk of illness and death and has disproportionate impacts on people who are underserved and overburdened (EPA).

Winners of the competition will be announced in Fall 2022 and their communication solutions about extreme heat are to be shared with communities across the U.S.

Potable Water Access to Help Manage Extreme Heat Risks

Extreme heat is and will continue to be present in our lives and a health hazard that we will need to actively manage. On Aug. 10, 2022, and per www.heat.gov, the National Integrated Heat Health Information System (NIHHIS) reported that approximately 21.5 million people in the U.S. were under active National Water Service extreme heat advisories, watches, and warnings. Extreme heat days projected in 2050 by NOAA are shown in Figure 4.

The importance in providing readily available potable water for consumption and assisting with cooling people who have overheated or are in danger of overheating cannot be overstated. Excessive heat in the U.S., and here locally in Florida, is real and is a part of our daily activities, especially during the summer. It’s important for us as water purveyors to provide the quantity and quality of potable water to sufficiently quench the increasingly thirsty Floridians impacted by the heat. S