Why swamp coolers will kill half of the New Mexican population, if the temperature in a heatwave exceeds ~115°F. No, I'm not being alarmist, it's thermal physics. If you're not convinced, downvote me. But read this please, because it could save your life.
You're reading that title, and thinking I'm a doomsdaying dumbass. I'm not. Approximately half the homes in the middle Rio Grande Valley use swamp coolers. All of you know that a swamp cooler increases humidity in the house. When it's unbearably hot, people turn these things on high and leave them on. It doesn't take much for the house to reach 80% humidity, especially when there's been any recent rain.
But here's the part where the swamp cooler kills you. Anyone familiar with the term "wet bulb event" knows that: (extreme heat + extreme humidity = human body can't cool off from sweat).
A swamp cooler at peak efficiency will only cool the temperature by a maximum of 20°F. At 80% humidity, a wet bulb event happens at 95°F. Which means that if it gets up to 115°F outside, we're going to have a mass casualty event. Climate change is making that kind of heatwave more likely every year.
The experts know this. The people don't. And the politicians are ignoring it. This should be the number one priority of the New Mexico government. We have to provide massive subsidies for every home to swap from swamp coolers to refrigerated air. Otherwise, it's not a question of if hundreds of thousands of New Mexicans will die, but when.
Edit: To address a few narratives in the comments
I am talking about indoor humidity, not outdoor humidity.
Yes, it gets up to 80% in many houses, I've measured it. One of the problems is that people think if they open their windows and doors, then they're letting the cold air out. People are going to be even more hesitant to open them if we get to 115°F. And even with good air flow, a large swamp cooler on high mode is dumping gallons of water into the indoor air, that can be very hard to combat.
Local HVAC companies are already getting "swamped" with calls from customers who think their swamp coolers aren't working because it's hot inside. Again, it only cools it off by 20°F, which means when it's 100°F outside, it's 80°F inside.
Yes, we can get increased humidity from rain at the same time as a heatwave. That's literally been happening over the past few weeks. Even a modest increase in outdoor humidity, makes a swamp cooler far less efficient at cooling the temperature indoors.
This is a fair one, I did say half the population would die. It would have been more accurate to say half the population is at RISK of dying.
Just turning the pump off, to let the fans air at the house sounds good. But in a 115°F heatwave, turning the pump off means that you're pumping that superheated air directly into the house, and raising the temperature to dangerous levels.
What can you do in the event of a 115°F heatwave, when you have a swamp cooler? The best thing to do is get refrigerated air. Unfortunately, that costs $10,000, while a swamp cooler costs $1,000. If you can't afford that, and we do get this kind of heatwave, open the doors and windows, turn on every fan, maybe even buy a several hundred dollar dehumidifier. Get the humidity down. And have a window AC unit in at least one room, so you can drop the temperature without raising the humidity. If that doesn't work, find a building with refrigerated air.