You may be wondering why I am writing an article about heat and humidity a few days before the start of winter and as some of the coldest air of the year is poised to enter the United States.  Some may even be saying, “Hey Dr. Shepherd, it’s snowing where I am, don’t you know that means global warming is a hoax.” I would respond “no it means that I understand the difference between weather and climate and that winter is here.” By the way, it is basically summer now for of half of the planet, and Forbes is read internationally. We are also about to end what is likely the 3rd warmest year on record, and reports say that it is likely Russia’s warmest year in the past 130 years. A new international study found that heat and humidity may be a deadly combination for people suffering with cardiovascular (heart) disease.

Researchers in the School of Public Health at the University at Albany collaborated with lead investigator Professor Cunrui Huang of Sun-Yat-sen University. This team, which included other researchers in Australia and China, investigated the role both heat and humidity play in heart disease deaths. The paper was just published in the International Journal of Environmental Research and Public Health. I usually try to avoid too much emphasis on one study. I written in Forbes before on why it drives me crazy to see too much inference into or dismal of science based on a single study. It is important to note that this study was focused only on  11 cities in the Zhejiang Province of China, but it did examine a robust sample of cardiovascular-related deaths (120,544) from 2010 to 2013. I would also caution that the study uses correlation, and the old saying “correlation is not always causation” is relevant.

The University at Albany study suggests that WHO may need to ask specific wording about heat and humidity to their list of precautionary actions aforementioned. Heat and humidity have long been silent killers. I am still amazed that people will rush their child off a football field if a lightning storm approaches (as they should) but think nothing about letting the child practice in full pads in 105 degree heat index conditions. Many people think nothing about exercising or working in extreme heat and humidity conditions. I wrote about this in my first contribution to Forbes two years ago. Heat is underestimated because the danger is not as visible or immediate as a tornado or hurricane. In the United States, heat has killed more people, on average, in the past 30 years than other weather events according to the National Weather Service.