Understanding heat risks for horticultural and floricultural workers

The United States, as much as Europe, is experiencing hotter days earlier and later in the year than in decades past, writes Debbie Hamrick for FCI. Staying safe in the summer heat means understanding and managing the risks and staying abreast of existing and future legislation. Mandated rules or no rules, ensuring worker health and safety moving forward, will require everyone in the ornamental horticulture industry to be cognisant of extreme heat and to take proactive steps to protect and safeguard employees.

There is a well-known American expression, ‘Never let them see you sweat.” For business people especially, it’s the ideal way to handle pressure. Never let on that you are experiencing stress even though underneath a calm exterior, you may be anxious for the right outcome and totally unsure that the situation will go your way.

While it might have a negative connotation, sweat is the human body’s evapotranspiration cooling system. Just as pads, fans, and/or mist help to cool greenhouses by evaporating water to lower air temperatures, sweat helps the human body maintain its internal temperature. But sweat doesn’t always work to keep us cool.

The number of days in the contiguous US from 1 April to 30 September annually over the years 1991-2020 is above the 95th percentile compared to the area’s climatological normal. Source: https://www.hhs.gov/climate-change-health-equity-environmental-justice/climate-change-health-equity/climate-health-outlook/extreme-heat/index.html

High heat can be fatal

Just like cooling a greenhouse with pads and fans, sweat needs to evaporate in order to be effective. However, this doesn’t happen with a combination of high temperatures and high humidity. Unfortunately, this deadly combination is creating life-threatening conditions for those working outdoors or in indoor conditions without conditioned air. The number of days of extremely high heat is climbing annually in most locations in the world, and the risks are becoming increasingly severe.

High heat can be fatal, especially for older adults, children and people with certain health conditions. The World Health Organisation (WHO) points out that high heat strains the heart and kidneys and can worsen conditions such as cardiovascular disease or diabetes. The negative effects of high heat on horticultural and floricultural workers are becoming an increasing concern.

Heat-related illness can first show signs in a worker through heat rash, muscle spasms, dizziness, light-headedness, or fainting. These can happen even if the person’s core temperature is not elevated. Heat exhaustion occurs with elevated core body temperature (>101.3°F/38.5°C). Symptoms of heat exhaustion can include headache, irritability, loss of coordination, nausea/ vomiting, weakness, and swelling of hands and legs. Sometimes, symptoms of heat exhaustion are hard to see. A person experiencing heat exhaustion may be so disoriented that they wave off a concern or attempt to help from a manager or co-worker.

Anyone experiencing these signs needs immediate medical care. Left untreated, heat illness and heat exhaustion can progress to heat stroke as the body’s core temperature keeps rising. This can result in seizures and damage to internal organs and muscles. Eventually, multiple organs can fail, and the person may go into a coma and later die.

Water, rest and shade

According to the United States Department of Health and Human Services, the risk of heat-related death is more than 35 times higher for people working in agriculture compared to other occupations. The Environmental Defence Fund, a non-profit based in the US, says that the average US agricultural worker is “exposed to 21 working days in the summer growing season that is unsafe due to heat”.

Maintaining hydration for workers is critical, but it is not enough. Water, rest, and shade are the three components that allow the human body to modulate its core temperature and prevent heat-related illnesses and heat exhaustion. The US Occupational Safety and Health Administration recommends that workers drink at least eight ounces/250 ml of cooled water every 20 minutes but should switch to electrolyte beverages (like sports drinks) for jobs lasting longer than two hours. Workers should also rest in shaded areas at regular intervals, as much as hourly in extreme heat.

Some outdoor occupations require workers to wear protective clothing and gear that would conflict with the heat rules.

Heat index

The United States is experiencing hotter days earlier and later in the year than in decades past. The net result is a total of more super-heated days and more days with critically high humidity in combination with high heat. Meteorologists now refer to the ‘heat index’ as well as the temperature in their weather forecasts. The heat index takes into account the humidity of the surrounding air and provides a “feels like” temperature. Just like the evapotranspiration greenhouse cooling systems, the higher the humidity, the less effective evaporation is to cool the human body. At 85 per cent humidity and 94°F/34°C, the human body is likely to experience heat stroke or sunstroke, both of which can be deadly.

Heat-related problems in the United States cause worker injury and illness. The US Bureau of Labor Statistics (BLS) Survey of Occupational Injuries and Illnesses estimates that there have been 33,890 work-related heat injuries and illnesses involving days away from work between 2011 and 2020, for an average of 3,389 each year. Since 2011, more than 400 US workers have died due to environmental heat exposure.
In a 2010 study published in the American Journal of Preventive Medicine, 94 per cent of farm workers in my home state, North Carolina, self-reported working in extreme heat conditions, while 40 per cent reported symptoms of heat-related illness.

This Heat Index Chart provides a guide to how the combination of heat and humidity affects the human body. Source: www.weather.gov/ffc/hichart

Workplace inspections

The United States Occupational Health and Safety Administration (OSHA) recognised that heat was becoming an increasingly prevalent factor that affected worker health. In 2022, they announced increased heat-related workplace inspections under the ‘National Emphasis Programme – Outdoor and Indoor Heat-Related Hazards’. The idea of the agency’s inspections was to prevent worker injury, illness or death from heat-related hazards. The agency says that as of spring 2024, they have conducted about 5,000 federal heat-related inspections.

To a degree, workers can be acclimatised to working in hot conditions. The US Centers for Disease Control (CDC) recommends gradually increasing the workload for workers in hot climates every day over the course of two weeks. They recommend that workers in hot environments totally cool off and rehydrate between work shifts as well as overnight. The CDC recommends that “acclimatisation requires at least two hours of heat exposure per day (which can be broken into two, one-hour periods).”

Being well-nourished, hydrated and physically fit will also assist workers in acclimatising to working in the heat. Often, it’s new employees who experience the greatest issues, so taking the time to acclimatise them to the working conditions is vitally important, the agency says.

However, when temperatures soar during a heat wave, even acclimatised workers are at risk. In that situation, it may be necessary to adjust working hours/conditions.

The CDC has an online bulletin on steps to acclimatise workers to heat here: www.cdc.gov/niosh/mining%5C/UserFiles/works/pdfs/2017-124.pdf.

The first day of work is the riskiest for employees

A study from California underscores the importance of acclimatising workers to the heat. In 2005, California’s Division of Occupational Safety and Health found that almost half of the reported incidences of heat illness and deaths were in unacclimatised workers. Almost half of all heat illness was reported on an employee’s first day of work and 80 per cent of heat illness happened in the first four days of work.

The issue has become so important for some government regulators that the Occupational Safety and Health Administration (OSHA) announced it will develop a regulatory framework through rulemaking: ‘OSHA Standard for Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings’. The comment period that announced the agency’s intention to develop rules for Heat Injury and Illness

Prevention in Outdoor and Indoor Work Settings drew 965 comments.

Since agricultural workers would be one of the primary groups of employees falling under the new rules, the industry has been quite vocal in asserting ideas and opinions about how the issue.

In short, US agriculture is highly concerned about another governmental agency issuing rules and conducting inspections that affect almost anyone with workers outdoors or working in hot environments (greenhouses/pack houses/kitchens, etc.) indoors.”

Where’s the logic?

There are always a number of concerns from the agricultural community whenever any governmental agency sets out to develop new regulations. One of the ones that inevitably arises is that responsible employers are already implementing the ideas proposed for regulation by the agency; therefore, the rule is not needed, and it could penalise employers for conducting themselves and their business in a responsible manner.

Another concern is that the agency already enforces ‘The Occupational Safety and Health Act of 1970’ that mandates employers to ensure a place of employment that “is free from recognised hazards that are causing or likely to cause death or serious harm to employees’. Again, the rule is not needed because the law states that employers must prevent harm to employees.

Many in the agricultural community ask about the logic of taking a national approach to an issue that should be managed at the site level. Producers, who are often working side-by-side with employees, are in the best position to determine how to effectively prevent heat stress because they see and know working conditions firsthand. Regulations are generally ‘one-size-fits-all’ rules that do not recognise regional climate variations, seasons and crop-specific labour needs.

Another major concern from the American fruit and vegetable industry is that producers in the US growing food for human consumption often must comply with regulations from other agencies that require the use of personal protective equipment (PPE) for food safety, which will conflict with the new OSHA heat-related illness and injury rules. Also, some outdoor occupations require workers to wear protective clothing and gear that would conflict with the heat rules. For example, in the arboriculture/tree care or forestry sectors,

The agricultural industry has also expressed concerns about what is considered hot in one region and not in another. So, how could a governmental agency assign a nationwide high-temperature threshold? For instance, in the south, 83°F/28°C is considered pleasant and comfortable, but in the Northeastern states, it could be considered hot. Altitude also plays into the body’s reaction to temperatures and creates distinct climates even within the same state.

I have never met a greenhouse producer, nurseryman or farmer who sought to harm employees. It’s also a fact that most horticultural jobs involve being outdoors or in a greenhouse. In the summer, it’s hot, it’s often dirty, and it can be wet.

US OSHA’s rules to be released this summer?

Leading growers and producers today have developed protocols for workers when environmental conditions are extreme. Managers are responsible for ensuring workers drink water, rest and cool down in the shade.

In the United States, in the not-too-distant future, we may be mandated to provide water, rest and shade through a national regulatory framework that is tied to benchmark temperature and humidity thresholds. We expect the US OSHA’s Heat Injury and Illness Prevention rules in Outdoor and Indoor Work Settings to be released this summer. However, mandated rules or no rules, ensuring worker health and safety moving forward will require everyone in the ornamental horticulture industry to be cognisant of extreme heat and to take steps to protect and safeguard employees.

Perhaps in the near future, sweating in public will be highly regarded.

This article was first published in the July-August 2024 issue of FloraCulture International. 

FloraCulture International Founder: Debbie Hamrick

Debbie Hamrick is FCI magazine’s founding editor and now Director of Specialty Crops, North Carolina Farm Bureau Federation. She may be reached at dhamrick1615@gmail.com