Safety Tidbit 4.30 - Cryptosporidium

Safety Tidbit 4.30 – Cryptosporidium

Reference: CDC General Information Page

Crypto has become one of the most common causes of waterborne disease (recreational water and drinking water) in humans in the United States. The parasite is found in every region of the United States and throughout the world.  Cryptosporidiosis is a diarrheal disease caused by microscopic parasites, Cryptosporidium, that can live in the intestine of humans and animals and is passed in the stool of an infected person or animal. You can become infected after accidentally swallowing the parasite. Cryptosporidium may be found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals.  To make matters worse, the parasite is protected by an outer shell that allows it to survive outside the body for long periods of time. The outer shell also makes it very resistant to chlorine-based disinfectants.

Crypto can be spread:

• By putting something in your mouth or accidentally swallowing something that has come into contact with stool of a person or animal infected with Crypto.
• By swallowing recreational water contaminated with Crypto. Recreational water is water in swimming pools, hot tubs, Jacuzzis, fountains, lakes, rivers, springs, ponds, or streams. Recreational water can be contaminated with sewage or feces from humans or animals.
• By swallowing water or beverages contaminated with stool from infected humans or animals.
• By eating uncooked food contaminated with Crypto. Thoroughly wash with uncontaminated water all vegetables and fruits you plan to eat raw. See below for information on making water safe.
• By touching your mouth with contaminated hands. Hands can become contaminated through a variety of activities, such as touching surfaces (e.g., toys, bathroom fixtures, changing tables, diaper pails) that have been contaminated by stool from an infected person, changing diapers, caring for an infected person, changing diapers, caring for an infected person.

Symptoms of cryptosporidiosis generally begin 2 to 10 days (average 7 days) after becoming infected with the parasite. The most common symptom of cryptosporidiosis is watery diarrhea, stomach cramps, dehydration. The symptoms generally last 1-2 weeks. If you suspect you may have crypto see your physician immediately.

Hope this was helpful and thank you for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have a new safety or health question, please let me know.

Safety Tidbit 4.29 - Calculating Outside Air

Safety Tidbit 4.29 – Calculating Outside Air

Reference: TSI Application Note: TSI-138

As I introduced in the previous Safety Tidbit, carbon dioxide concentration is common indicator of indoor ventilation.  We can measure the carbon dioxide easily enough (I like the TSI Model 7575). Since each of us is a CO₂ generator, how do we determine if there is enough outside air brought in to dilute the build-up of CO₂?

Percent outdoor air (%OA) is the percent of the total volume of delivered air that is outdoor air. There are a few ways to determine %OA such as using sulfur hexafluoride tracer gas or, similarly, measuring the concentration of CO₂. However, I think taking three measurements of CO₂ and calculating the %OA is the easiest (temperature can be use in place of CO₂). The three locations to take the measurements include outdoor air, supply air, and return air.

To calculate the %OA follow:

Where:

Xr = CO₂ concentration in the return air

            Xs = CO₂ concentration in the supply air

            Xo = CO₂ concentration in the outside air

Now all you need to do is take the three measurements. A few common pitfalls to taking readings include:

·      Supply air is mixing with room air

·      Return air is not mixed well

·      Outdoor air measurement is tainted

·      Not enough occupants to generate high enough CO₂ levels

Remember if you have a room where several people will be working for extended periods of time think of their health and measure the carbon dioxide levels during the height of the workday to ensure the HVAC system is performing adequately. Otherwise, your folks could be nodding off on the job.

Hope this was helpful and thank you for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have a new safety or health question, please let me know.

Safety Tidbit 4.28 - General Indoor Air Quality

Safety Tidbit 4.28 – General Indoor Air Quality

Reference: ASHRAE 62.1-2016

The quest for acceptable indoor air quality (IAQ) is significant, especially with the design of “air tight” and energy efficient buildings.  Usually this term is applied to non-manufacturing spaces where it is not expected that significant release of toxic contaminants occurs.  Carbon dioxide has become used consistently as an "indicator" of air quality since it will tend to "build up" in spaces that are not provided with sufficient amounts of outside, dilution air.  ASHRAE has recommended that carbon dioxide levels not exceed 1000 ppm above the ambient levels, i.e., those of outside, "fresh" air.

ASHRAE also recommends other guidelines as measures of indoor air quality, among them are volumetric flow rates or outside air per occupant, relative humidity levels, air temperature ranges and maximum air velocities across occupants.  ASHRAE recommends 20 cubic feet per minute of outside air per person in most indoor spaces. They recommend relative humidity should range between 30% and 60%. Winter temperatures should be kept between 68-76 degrees Fahrenheit and 72.5-80 degrees during the summer.

ASHRAE contends that compliance with their guidelines will assure that at least 80 percent of the occupants will be "satisfied" with the air quality.

Hope this was helpful and thank you for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have a new safety or health question, please let me know.

Safety Tidbit 4.27 - Surge Protector vs GFCI

Safety Tidbit 4.27 – Surge Protector vs GFCI

A GFCI works based on current (i.e. the number of electrons), it detects if the amount of current being sent down one wire doesn't match the amount coming back down the other. An imbalance indicates that electricity is probably going somewhere it shouldn't.

A surge protector works based on voltage. If the voltage on a wire gets a lot higher than it's supposed to be then the surge protector will work to prevent that voltage spike from affecting your stuff.

A "ground" is simply a place that a lot of electricity can go. Generally, things that are connected to ground are things that are not supposed to be energized, and the ground works to keep them from being energized if something bad happens. So, for example, if a wire in your stove breaks and touches the metal body, the fact that the metal body is grounded means that electricity will go to the ground instead of trying to go through you the next time you touch it.

In the case of a faulty wire touching the metal body of a toaster, what happens if:

·       You only have a GFCI, no ground, no surge protector.

In this case, I would guess that at the time the wire touches the metal body, nothing happens, but as soon as a human touches the toaster, the electricity will want to go through the human. But, because it won't be going back into the system, the GFCI will cut off power?

·       You only have a surge protector, no ground, no GFCI.

In this case, I guess nothing protects you? The current goes through you, but there's no actual voltage difference, so the surge protector doesn't care? How does the surge protector 'know' to only care about voltage, and not about current? Or: is it that current going through a human won't be too much current overall?

·       You only have a ground, no GFCI, no surge protector.

So here, as soon as the wire touches, the ground gives it a path to follow, so that causes a short circuit and we blow the fuse/trip the circuit breaker as soon as the wire hits?

Hope this was helpful and thank you for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have a new safety or health question, please let me know.