Wildfires are getting bigger and happening more often. They are destroying communities and ecosystems all over the world. Since temperatures around the world are going up, it’s more important than ever to reduce the risk of wildfires.
A major report from the United Nations says that climate change will make what the report calls a “global wildfire crisis” even worse in the coming decades. This means that there will be more dangerous wildfires all over the world.
The United States Environmental Protection Agency says that wildfires happen most often in the western part of the country, where there are more than 2 million dairy cows that make more than 25% of the country’s milk. Recent data from the EU shows that wildfires have burned down almost 660,000 hectares of land in Europe this year.
Fine particulate matter (PM2.5) is released into the air by wildfire smoke. This is a known air toxin that is thought to make people sick by causing inflammation. A lot of research has shown that people who are exposed to PM from wildfires are more likely to get sick and die. However, not much is known about how PM affects dairy cattle.
Researchers looked at how milk production and the immune system of lactating dairy cows change when they are exposed to high levels of wildfire-derived particulate matter (PM2.5) alone or with high temperature-humidity index (THI). The study was done at the University of Idaho Dairy Centre in 2020 during the wildfire season in the Pacific Northwest (July to September). Cows were kept in open-air barns with free-stalls and were exposed to PM2.5 from wildfires when both of the following were true:
daily (24-h) average PM2.5 concentration was higher than 35 g/m3. AirNow-Tech Navigator wildfire and PM2.5 maps, along with HYSPLIT air mass trajectory mapping, showed air plumes moving from areas with active wildfires to the study site.
The study found that changes in blood chemistry and haematology that happen when THI and PM2.5 levels go up together cause innate immune dysregulation, which makes people more likely to get sick and die.
When both THI and PM2.5 were higher, the number of eosinophils and basophils went up, but the number of red blood cells and haemoglobin went down. Eosinophils and basophils are often found in the body during an allergic reaction. This suggests that PM2.5 from wildfires may cause an allergic reaction in dairy cows.
“…we think there will be more wildfires in the coming years.”
“The low RBC count and haemoglobin concentration could be caused by stress or PM toxins that cause more haemolysis.” “Because haemoglobin helps move oxygen and carbon dioxide through the blood, less haemoglobin may also be linked to less oxygenation of tissues and more CO2 buildup,” said the researchers.
“In our study, when cows were exposed to PM2.5 from wildfires, the amount of CO2 in their blood went up. Elevated CO2 can be caused by slow, shallow breathing, more CO2 being made, and alveolar hypoventilation. It can also be a sign that the body is trying to make up for metabolic alkalosis or respiratory acidosis. On the other hand, higher CO2 levels in the blood could be linked to more CO2 in the air because of the smoke from the wildfires,” they said.
How milk is made and what’s in it
The study’s results showed that breathing in PM2.5 from wildfires affects milk production, even when THI is not a factor. This may be because of changes in how the body uses macronutrients. The researchers said, “Our data show that inhaling PM2.5 decreases daily milk production in dairy cows by an average of 1.2 kg/cow for every 100-g/m3 increase in PM2.5, not only on the day of exposure, but also up to 7 days after the last day of smoke exposure.” The amount of protein in milk decreased by 0.14 percent for every 100 g/m3 of PM2.5 on the day of exposure. Fat percentage and lactose yield also went down at the same time that THI and PM2.5 went up.
It was decided that “the mechanisms involved in PM’s effects on milk yield and composition are unclear, but they may be linked to slowed mammary gland development or cellular turnover, or disruption of endocrine or metabolic processes, as has been shown for the toxic effects of other chemical compounds on a variety of tissues.”
Wildfires and greenhouse gas emissions
“As greenhouse gas emissions rise and drought and heat continue, we expect more wildfires in the years to come, especially since fire seasons are getting longer,” say climate experts from the Environmental Defense Fund (EDF).
According to a BBC report, Dr. Friederike Otto, a senior lecturer in climate science at Imperial College London, said, “Fires need high temperatures, dry conditions, and strong winds.”
“We have the power to break the cycle and get on the path to a more sustainable future,” said the EDF. We can keep spending more and more money to fight fires and other weather disasters that are made worse by climate change, or we can work together to slow and eventually stop the greenhouse gas emissions that are heating up our planet.