In December 2006 Great Wolf Lodge in Mason, Ohio, opened as the
ninth indoor waterpark resort for the brand. Opening an 84-degree
indoor waterpark in the middle of winter in Ohio was expected to be
a draw to the region. What wasn’t expected were issues with
indoor air quality.
After a successful grand opening, the property was in full swing by
the time flu season heated up. Perhaps that’s why a number of
guests reported flu-like symptoms, such as coughing. A logical
conclusion, but the fact that some guests reported skin irritation
(which can result from prolonged exposure to a chlorinated
environment, especially during a dry, cold winter) meant perhaps
the culprit was something else: chloramines.
Found wherever there are swimming pools, these chemical compounds
are produced when organic agents such as sweat or urine mix with
the chlorine in the water.
But how could that be a problem at our brand-new facility? Our air
and water quality tested safe and normal. The waterpark was in
compliance with all the state Health Department and Agriculture
Department regulations, and we exceeded compliance with the Ohio
Basic Building Code for our ventilation system. Still, this
information proved contrary to the unfavorable effects that some
guests were experiencing.
The local health department, Warren County Combined Boards of
Health, was made aware of these conditions and asked for the
assistance of the National Institute of Occupational Safety and
Health. As a result, an investigation was launched in March
Up until this point, indoor air quality was determined by
engineering meant for natatoriums. At the time, this was thought to
be sufficient, but maybe there was a better way for our waterpark.
I began reading every bit of research I could get my hands on. In
addition to NIOSH’s investigation, which we actively
participated in, we brought in a nationally recognized ventilation
expert and worked with our design/engineering firm to find
After 15 months of ongoing investigation, the NIOSH report was
issued. The findings attributed the short-term discomfort in less
than 1 percent of the total bathers to elevated levels of
chloramines during high bather load periods. The results of
NIOSH’s testing showed our chloramine levels were in the
range of other indoor swimming pool environments where irritation
could occur. This information was beneficial because there
isn’t an exposure standard for chloramines, and we finally
had scientific research on which to base our design and
In the end, we made operational changes that defied traditional
waterpark operations and HVAC philosophies. I am proud to say that
we proactively completed the vast majority of NIOSH’s
recommendations well before the report was released. In fact, many
of the recommendations were changes we suggested and were
First, while our chlorine levels have always been in the safe and
normal range for disinfection, we recognized that some more
sensitive guests can have a reaction even to approved levels for
chlorinated water, especially in cases of prolonged exposure. The
levels suggested by health departments often are meant for outdoor
pools that experience UV and high user loads that peak suddenly.
But we have indoor pools with a limited occupancy, so, with
permission from the Ohio Agriculture Department and the Ohio Health
Department, we voluntarily reduced chlorine levels. This allowed us
to maintain chlorine near 1 ppm, and a lower pH near 7.2 –
7.4 because we had excellent control and UV for disinfection.
Second, we’ve always met or exceeded state ventilation
requirements, but we took our ventilation system a step further and
increased our waterpark’s air flow by 10 percent. We also
lowered our return vents so we would collecting the worst air near
the pool surfaces. To help further improve air flow near the pool
surfaces, we also dropped our supply vents and decreased our
chlorine levels to close to 1.2 ppm and our pH to 7.3. Less
chlorine means we were making fewer chloramines. We have to keep pH
low to make sure we were reaching optimum disinfection. These
practices were very different from traditional water chemistry for
high bather load facilities.
While all of the recommendations from the NIOSH report were
implemented, it is important to note that in a cold weather
climate, it is hard for anyone to guarantee that someone
won’t feel skin irritation if they have dry skin, are
sensitive to chlorine and stay in a chlorinated environment for
prolonged periods of time. It’s also difficult to predict how
many people will have flu-like symptoms during flu season, as well
as to discern the cause of their symptoms.
For that reason, we also focused on education. We expanded our
employee education and reporting process to be able to identify and
resolve any health concerns immediately.
To ensure that all guests have the best possible visit, we
increased education at all points, including check-in, in guest
rooms, and in the waterpark. This included a recommendation that
guests take soap showers before and after using the waterpark.
Additionally, we recommend limiting hot tub usage to 15 minutes at
As an industry leader, Great Wolf Resorts is determined to lead the
nation in the development of waterpark technology and safety
standards. That's why we’ve also used the research we
gathered over the past two years to educate others. I lead the
subcommittee on ventilation for the Model Aquatic Health Code
project, which is being championed by the Centers for Disease
Control and Prevention. Along with that, I’ve presented
seminars to operators, designers and sanitarians at the World
Waterpark Association annual symposium, the Ohio Indoor Air Quality
summit, and the American Industrial Hygienists Association annual
After the NIOSH air quality report was released, we also worked
diligently to regain trust. We wanted previous guests and
prospective guests to know that the indoor waterpark at Great
Wolf Lodge in Mason is safe. Since it opened, nearly 1 million
guests have experienced our indoor waterpark.
In the end, I’m proud to say our improvements have become a
part of our regular operations and as a result of our hard work,
Warren County Combined Boards of Health has not received any
additional complaints since the original cases nearly three years ago.