Defeat the Summer Bugs

Working Outdoors in Summer – Part 1

by Jan Semenoff

We are shaking off an unseasonably long winter and late spring in most of North America this year, and thankfully, summer is here. No more heavy coats, long-johns or frost bite. Unfortunately, summer months bring other occupational exposure hazards…

West Nile Virus

West Nile Virus is a virus commonly found in Africa, West Asia, and the Middle East. It is closely related to St. Louis encephalitis virus which is also found in the United States. The virus can infect humans, birds, mosquitoes, horses and some other mammals.

The most severe type of disease due to a person being infected with West Nile virus is sometimes called “neuro-invasive disease” because it affects a person’s nervous system. Specific types of neuro-invasive disease include:

§ West Nile encephalitis,

§ West Nile meningitis or

§ West Nile meningoencephalitis.

These diseases create inflammations (swelling) around the brain or spinal cord. West Nile Fever is another type of illness that can occur in people who become infected with the virus.

Signs and symptoms of West Nile Virus include:

§ fever,

§ headache,

§ tiredness,

§ aches and

§ occasionally a rash.

Although the illness can be as short as a few days, even healthy people have been sick for several weeks. Obviously, prevention of contact with infected mosquitoes is the key. You should note that bug repellents will also help ward off other diseases such as encephalitis, lime disease, and flea, black fly and tick bites.

DEET

Look for bug-repellent products containing DEET ( N,N-diethyl-meta-toluamide) and apply them to exposed skin when you go outdoors. Even a few minutes outdoors can be long enough to get a mosquito bite. Many people are concerned with the long term exposure effects to DEET. In a study that will be published in the New England Journal of Medicine in July, researchers at the University of North Carolina conclude that DEET has two strengths:

§ It has been used for more than 45 years by millions of people with fewer than 50 cases of significant toxicity. "In many of those cases, there was excessive, very inappropriate use of a DEET product in which someone was applying a high-strength formulation and covering large areas of skin for many days in a row," said Dr Mark Fradin, a dermatologist who co-authored the study with medical entomologist Dr. Mark Day.

§ Products containing higher DEET concentrations were far more effective than products that contained alternative repellents.

o The three products that provided the longest-lasting protection against mosquito bites all contained DEET.

o The duration of protection increased as the amount of DEET in the product increased: a product containing 6.65% DEET protected on average slightly less than 2 hours, while a product containing 23.8% DEET protected for an average 5 hours.

o One product containing 2% soybean oil protected for an average 95 minutes, and one product containing the chemical IR3535 protected for an average of only 23 minutes.

o Products containing citronella (a plant-derived oil) were the least effective among the liquid products: none of them protected for more than 20 minutes. The products in this group included a moisturizer that is commonly believed to ward off mosquitoes.

o The wristband products did not provide any protection - mosquitoes began biting as soon as the arm with the wristband was exposed.

Evaluation by the United States Environmental Protection Agency, which regulates products such as DEET, indicates that it is safe to use insect repellents containing DEET and sunscreen at the same time. The United States Center for Disease Control recommends using two separate products because sunscreen requires frequent applications while bug repellents containing DEET should be used sparingly. Follow the directions on the package for each product, and consult your physician or pharmacist if you have questions.

Tips for use of Insect Repellents

Always read the entire label carefully before using. Follow all of the label directions, including restrictions for use on young children and the maximum number of applications allowed per day.
Apply the repellent sparingly, and only on exposed skin surfaces or on top of clothing. Do not use under clothing. Heavy application and saturation are unnecessary for effectiveness. Repeat applications only as necessary.
Do not get in eyes. If you do get repellent in your eyes, rinse immediately with water.
Do not use the repellent on open wounds, or if your skin is irritated or sunburned.
Avoid breathing spray mists and never apply sprays inside a tent. Use only in well-ventilated areas. Do not use near food.
Wash treated skin with soap and water when you return indoors or when protection is no longer needed.
Children under 12 years of age should use insect repellents containing 10% DEET or less.

Clothing

When possible, wear light colored clothing, including long-sleeve shirts, long pants and socks when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing permethrin or DEET will give extra protection. Don't apply repellents containing permethrin directly to skin. Do not spray repellent containing DEET on the skin under your clothing.

Peak Mosquito Hours

The hours from dusk to dawn are peak mosquito biting times for many species of mosquitoes. Take extra care to use repellent and protective clothing during evening and early morning -- or consider avoiding outdoor activities during these times.

Mosquito Prevention

Mosquitoes lay their eggs in standing water. Control the number of places around your workplace and home for mosquitoes breeding pools by eliminating items that hold standing water. Also, trim back dense vegetation - also a great tip for crime prevention, as the article on CPTED showed.

Mosquitoes and West Nile Virus aren’t the only hazards faced by workers outdoors. Take a look at the article on heat injuries in “Working Outdoors in Summer – Part 2”.