The wildfires at Saddleworth Moor and Winter Hill are likely to have had a “shocking impact” on air quality, according to a new study.
The devastating blazes were battled by hundreds of firefighters and soldiers in June and July.
Researchers said the impact of the summer fires on public health in the region could be “considerable”.
Evidence suggests “a significant negative effect on air quality” in Greater Manchester and beyond.
The paper, which was published earlier, found that during the period of the fires, levels of “particulate matter” (particles in the atmosphere), linked to serious conditions such as asthma, lung cancer and infant mortality, were “extremely high”.
When the fires were at their height, the legal limit for daily average exposure to particulate matter (50ppm) was breached on five occasions in different sites across Greater Manchester, the report by north of England think tank IPPR North says.
Monitoring stations also registered extremely high individual spikes in excess of 150ppm.
The Saddleworth blaze broke out on 24 June and about 100 soldiers were drafted in to help tackle it at its height.
At its peak the fire covered an area of 7 sq miles (18 sq km) of moorland.
Police are treating the blaze as arson after people were seen lighting a bonfire on the moors near Stalybridge.
Hundreds of firefighters also tackled the Winter Hill blaze, which broke out four days after the Saddleworth fire, and spread across 7 sq miles (18 sq km) of land.
Two men have previously been arrested over the Winter Hill fire and both were released under investigation.
Report author and research fellow Jack Hunter said: “The impact of the fires at Winter Hill and Saddleworth Moor provide a timely reminder that we must not take the north’s natural assets for granted.
“If we don’t value the natural environment properly, the consequences for people, the environment and the Northern Powerhouse economy can be disastrous.”
Mr Hunter said policymakers “need to put the natural environment right at the heart of decisions” about the future of the north of England.
Environmental concerns raised in the report follow previous research which found that Greater Manchester had “lethal and illegal” levels of NO2 air pollution.
via Moorland fires had ‘shocking air quality impact’ – BBC News