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Develop a heat and air quality safety plan for your farm workers

Quick facts

  • Create a heat safety plan based on the heat index.
  • Understand the symptoms of heat illness.
  • Check the air quality forecast.
  • Use respirators and eye protection when necessary.

High heat and humidity can make it dangerous for growers to work outdoors. While wildfire smoke and other air pollutants can make it dangerous for growers to breathe the air while working outdoors.

Here are some best practices for protecting yourself and your employees.

Pay attention to the heat index

To determine the risk of working in hot conditions, pay attention to both heat and humidity. The combination of these things is called the heat index. Download the OSHA-NIOSH heat safety tool to get your location's heat index and risk at any given time.

If you don't have a smartphone, consider purchasing a wet bulb thermometer for your farm. Wet bulb thermometers provide a more accurate measure of the “real feel” than temperature alone. 

Create a heat safety plan based on the heat index

The chart below outlines the number of minutes workers should rest per hour and the recommended hourly fluid intake based on easy, moderate, and hard work at various heat indexes. 

  • Easy work: Sitting with minimal hand and arm work, slow walking, stooping, crouching, kneeling. 
  • Moderate work: Pushing and pulling light carts, picking fruit or vegetables, continuous normal walking, driving or operating mobile equipment, using hand tools. 
  • Hard work: Intense arm and trunk work, carrying loads, shoveling, pushing and pulling heavy carts or wheelbarrows, fast walking (more than 4 mph), manually lifting and lowering loads.

Work, rest and hydration recommendations based on heat index

Risk at 'real feel' temperature
(WBGT index)
Easy work Work/Rest (min) Moderate work Work/Rest (min) Hard work Work/Rest (min)
Minimal risk
Work/rest: Self-determined
Water: 0.5 qt. per hour
Work/rest: Self-determined
Water: 0.75 qt. per hour
Rest: 40/20
Water: 0.75 qt. per hour
Low risk
Work/rest: Self-determined
Water: 0.5 qt. per hour
Rest: 50/10
Water: 0.75 qt. per hour
Rest: 30/30
Water: 1 qt. per hour
Moderate risk
Work/rest: Self-determined
Water: 0.75 qt. per hour
Rest: 40/20
Water: 0.75 qt. per hour
Rest: 30/30
Water: 1 qt. per hour
High risk
Work/rest: Self-determined
Water: 0.75 qt. per hour
Rest: 30/30
Water: 0.75 qt. per hour
Rest: 20/40
Water: 1 qt. per hour
Extreme risk
Rest: 50/10
Water: 1 qt. per hour
Rest: 20/40
Water: 1 qt. per hour
Rest: 10/50
Water: 1 qt. per hour

*These fluid and rest recommendations are based on healthy individuals under age 40 wearing normal work clothing. Certain health conditions, as well as the use of personal protective equipment, can exacerbate heat stress, and modifications should be made based on individual needs. 

Proper hydration is essential to prevent heat-related illness. When people sweat, they lose salt and electrolytes. Eating regular meals with adequate water intake is enough to maintain water and electrolyte balance.

Individuals can sweat up to 1 liter per hour. For prolonged sweating lasting several hours, sports drinks with balanced electrolytes are an option to replace salt lost in sweat. Avoid alcohol and beverages high in caffeine, as they can contribute to dehydration.

Dehydration is often a delayed response to heat illness; by the time you feel thirsty, you are already dehydrated. A better indicator of hydration status can be the color of urine. The darker the color of urine, the more dehydrated you are. Setting an alarm for water breaks based on the table above can help ensure adequate hydration.

Acclimatize workers and volunteers

During the hottest months of the year, it is recommended to gradually expose yourself and your employees to the heat over 1 to 2 weeks. The general rule is to increase activity and exposure by 20% each day. However, the daily exposure of each individual depends on the difficulty of the work, if the environment is new to the person, and the underlying health of the individual. Proper acclimatization can increase productivity by reducing the risk of injury and increasing performance during periods of extreme heat. 

The National Institute for Occupational Safety and Health (2018) provides the following recommendations:

  • For new workers, the schedule should be no more than a 20% exposure on day 1 and an increase of no more than 20% on each additional day.
  • For workers who have had previous experience with the job, the acclimatization regimen should be no more than 50% exposure on day 1, 60% on day 2, 80% on day 3, and 100% on day 4.

Risk factors for heat illness

Many health and occupational factors can increase the risk of suffering from heat illness. Unfortunately, farmers are generally at greater risk due to the nature of their work (hard work, long hours, sun exposure, etc.), which means the consideration of other risk factors is even more important. Additional risk factors include: 

  • Personal: Heart disease, diabetes, high blood pressure, lack of sleep, cold, fever or flu, certain medications, previous heat illness, being overweight, pregnancy, older age, and consumption of caffeine and sugar.
  • Work-related: Working near hot machines, lack of ventilation in the work area, wearing personal protective equipment, wearing dark clothing or too many layers, not enough breaks, and heavy workloads.
  • Weather-related: Direct sun, high temperatures, no wind or hot wind, and high humidity.

Understand the symptoms of heat illness

Know the signs of heat stroke vs. heat exhaustion, and call 911 immediately if you or someone on your farm exhibits symptoms of heat stroke. Progression from heat exhaustion to heat stroke can happen within minutes and recognizing the symptoms early can mean the difference between life and death.

Heat stroke: What to look for

  • High body temperature (103°F or higher)
  • Hot, red, dry, or damp skin
  • Fast, strong pulse
  • Headache
  • Dizziness
  • Nausea
  • Confusion
  • Losing consciousness (passing out)

What to do

  • Call 911 right away; heat stroke is a medical emergency.
  • Move the person to a cooler place.
  • Help lower the person’s temperature with cool cloths or a cool bath.
  • Do not give the person anything to drink.

Heat exhaustion: What to look for

  • Heavy sweating
  • Cold, pale, and clammy skin
  • Fast, weak pulse
  • Nausea or vomiting
  • Muscle cramps
  • Tiredness or weakness
  • Dizziness
  • Headache
  • Fainting (passing out)

What to do

  • Move to a cool place.
  • Loosen your clothes.
  • Put cool, wet cloths on your body or take a cool bath.
  • Sip water.

Get medical help right away if:

  • You are throwing up.
  • Your symptoms get worse.
  • Your symptoms last longer than 1 hour.

Check the air quality forecast

Throughout the summer, check the Minnesota Pollution Control Agency’s air quality forecast daily. This forecast provides a 3-day outlook for air quality in Minnesota. As much as possible, try to plan your most intense outdoor activities during windows when air quality is better.

Another resource that offers an up-to-date air quality index is AirNow.gov.

Precautions for poor air quality*

Air Quality Index What to do
Less than 50: good No specific precautions.
51-100: moderate Limit time outdoors, especially if you have asthma or another condition.
Consider wearing a respirator while outdoors.
101-150: unhealthy for sensitive groups Stay indoors if possible, especially if you have asthma or another condition.
Limit time outdoors to no more than a few hours per day.
Wear a respirator while outdoors.
151-200: unhealthy Stay indoors if possible.
Keep windows and doors closed.
Use an indoor air filter.
Wear a respirator, especially while outdoors.
If you need to work outdoors, take frequent breaks indoors in a room with an air filter.
Over 200: very unhealthy Stay indoors.
Keep windows and doors closed.
Use an indoor air filter.
Wear a respirator, especially while outdoors.
Consider evacuating to a place with safer air.

*Chart adapted from the Wildfire Action Plan handout for patients from Americares.

How smoke and air pollution affect health

Smoke particles are extremely small, which means smoke can reach deep into the lungs and affect your heart and circulatory system. Pollution from smoke can have immediate and long-lasting health effects, including:

  • Heart attack
  • Irregular heartbeats
  • Aggravated asthma and Chronic Obstructive Pulmonary Disease (COPD)
  • Decreased lung function
  • Irritation of airways, coughing, wheezing, or difficulty breathing
  • Eye, nose, and throat irritation
  • Bronchitis and pneumonia
  • Adverse birth outcomes
  • Premature death

Use a respirator

Employers should provide respirators to employees free of cost.

  • Use the following types of respirators to protect yourself: N99, N100, R95, R99, R100, P95, P99, and P100.
    • N95 respirators provide protection, but not as much as those listed above.
  • Train employees to wear respirators properly.
  • Surgical masks and bandanas or other face coverings do not protect from the very small particles created by wildfires and ozone.
  • Discard respirators after 8 hours. 

Protect your eyes

Air pollutants can temporarily and permanently damage the surface of your eyes, causing redness, irritation, scratches, conjunctivitis, and potential vision loss. Prolonged, repeated exposure can lead to stress on the eyes, increasing the risk for eye diseases such as glaucoma and retinopathy. The American Optometric Association recommends protecting eyes during times of unhealthy air quality.

  • Consider wearing sunglasses or goggles.
  • Wear eyeglasses instead of contacts.
  • Use eye drops.
  • Do NOT rub your eyes.

Take breaks in areas with clean air

When the air quality index reaches 101, growers should reduce their work hours and take frequent breaks.

  • If possible, take breaks indoors in a cool room with a filter.
    • Keep all windows and doors closed to prevent smoke or pollution from entering.
  • You can purchase a portable HEPA air filter, or make a Corsi-Rosenthal air filter, which may be more effective than HEPA filters, by combining furnace filters, cardboard and a box fan.

Authors: Natalie Hoidal and Katie Black, Extension educators; Pang Lor, Kent Boyd, Melissa Thone, University of Minnesota Doctor of Nursing Practice Program

Reviewed in 2024

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