The government helicopter team we are with is charged with locating hotspots - fires belching toxic fumes into the atmosphere and poisoning the air.
Tiny PM2.5 pollution particles caused an estimated 32,000 premature deaths in Thailand in 2019, according to the State of Global Air 2020 report.
Along with exhaust fumes and crop burning, smoke from the wildfires contributes to the problem.
The chopper team is focusing on a densely forested area of a national park near the city of Chiang Mai.
As we sweep low over the jungle, columns of smoke rise from between the trees.
The thick canopy hides the flames, but the smoke helps them to pinpoint where to drop the buckets of water the three helicopters are carrying.
Most of the targets are remote spots burning deep in the forest which are too inaccessible and far from water to fight from the ground.
On our mission, they are especially worried about a large fire that they have already been fighting for two days.
The flames have travelled up towards the top of the ridge line. The concern is, if they don't manage to control it, the fire will jump over the top of the steep hill and spread very quickly down the other side.
Hour after hour, the team empty bucket after bucket of water onto the blaze - thousands of litres needed to douse a fire started in this case by humans.
"It's very bad, we do not have enough water for the wildfires," Captain Sakchai Chooim, our pilot from Thailand's ministry of natural resources, tells me over the radio.
In various "war rooms" across northern Thailand, experts from the government, emergency services, military and academics monitor the fires.
We are told during our visit to one that about 1,000 fire fronts are burning in the area.
A hotspots map is lit up with tiny red dots showing all the problem areas both in Thailand and across the border in Myanmar and Laos.
While officials say they've reduced the number of local blazes by 40% this year, those lit in neighbouring countries continue to pump smoke into the area adding to the oppressive haze.
State agencies are supported by volunteers including The Mirror Foundation, who trek to wildfires to try to fight the flames from the ground.
On the day we join them it's already 38C (100F) by mid-morning - before we have stepped anywhere near a fire.
We are told to wear cotton clothes that won't melt or set alight easily.
As we may have to walk for several hours through the jungle, long sleeves and chunky boots are a must to protect from insects, snakes and sparks.
Just before we head in, one of the team gives me a cotton scarf.
"It's to protect your face from angry bees whose home has been affected by the fire," he explains.
On that note, we make our way into the jungle in a long line.
Some of the volunteers carry hoses while others have water tanks on their backs.
There's no water source nearby so all of the water we need has to be carried in.
As we walk up and down a range of steep hills, piles of dry leaves crunch beneath our feet.
"Everything's dry, absolutely dry so fires can start very easily," says David Root, a British volunteer at the Mirror Foundation.
"Some of them are natural and some of them are started by local farmers."
In addition to the portable water tanks and sprayers, the leaf blowers are the other key bit of kit being used.
"With water we put out the edge of the fire and with the leaf blowers we make a fire break," David explains.
While the majority of the current fires are in the forest, farmers also burn crops that add to the haze.
On the worst days this year, drifting smoke made Chiang Mai the most polluted city in the world.
"As the years have progressed it's just getting worse and worse," David explains.
For the last few years, Northern Thailand is just swathed in smoke for eight weeks of the year which causes a lot of health problems," David explains.
In the first three months of this year 200,000 people in eight provinces in northern Thailand have been made ill by PM2.5 according to health officials.
"Most of them have just sniffles of maybe rhinorrhoea or something like that, some have conjunctivitis, some have irritated skin... they do not come to hospital."
"Most of the people who went to hospital already had chronic diseases," says Dr Suwanchai Wattanayingcharoen, director-general of the ministry of public health.
"Thailand is trying to solve the root of the problem. In Bangkok and the periphery, it is using clean energy and fuel which is environmentally friendly and doesn't cause PM2.5," he says.
"In the northern region, it's changing farming behaviour."
At the main hospital in Chiang Mai, we meet three-year-old Porjai who has a lung infection.
"Every year, when it gets like this, my child has symptoms," her mother Duangduen Pijja, tells us.
"She has to come to see the doctor every year. Adults also cough and have dry throats - now, I do too," she says.
Authorities say they have reduced hotspots this year, are monitoring pollution and trying to better control crop burning.
But cleaning up the air is a huge challenge. The annual fires with their toxic haze are damaging tens of thousands of lives.
Sky News will this week launch the first daily prime time news show dedicated to climate change.
Hosted by Anna Jones, The Daily Climate Show will follow Sky News correspondents as they investigate how global warming is changing our landscape and how we all live our lives.
First airing on Wednesday 7 April, the show will also highlight solutions to the crisis and show how small changes can make a big difference.