If residents of China’s steel belt want to know whether to strap on face masks and avoid outdoor exercise, they could do worse than look to the iron ore price.

That’s because the spread between two varieties of rust often works as a proxy for the amount of choking particulates spewed out by the country’s steel mills. Right now, the narrowing of the differential to its tightest in more than three years is flashing a pollution warning signal.

Unprocessed iron ore is sold in two main sizes. Lump ore is a pebbly mixture that can be fed directly into blast furnaces, and in China must be imported from overseas. Typically it commands a steep premium over fines, a more powdery product that’s easier to come by and must be processed with coke and limestone in sinter plants before it can be used.

Those sinter plants are where the vast majority of dust is produced in the steelmaking process, so when environmental restrictions are tight and rigidly enforced, mill owners will use more lump ore and the lump premium rises. At the moment, the opposite is the case: At just 5.5 cents a metric ton, the premium has narrowed by about 80% since the start of March to levels last seen in 2017. Enforced shutdowns are often imposed in China’s steel belt when pollution gets bad, but they’re widely flouted, especially when profits are good and the government is prioritizing heavy industrial stimulus. With those conditions in place, there’s little reason for mills to buy more lump.

After a coronavirus-induced lull earlier in the year, the country’s steel industry is churning out metal at record rates to get the economy off its sick bed. Many businesses are still reeling, with first-half fixed-asset investment in the dominant manufacturing sector falling 12% from 2019, and wholesaling and retailing down 31%. Yet steel-intensive engineering sectors are surging. Spending on new power generation and utilities was up 18% from last year. Even the immense real estate sector, which accounts for about a quarter of all Chinese fixed-asset investment, increased 0.6% through June.

That has translated to buoyant conditions for steel mills. In May alone, a record 92 million tons was produced, more than the U.S. steel industry has made in any year since 2007. Despite a price surge for benchmark iron ore that last week prompted the Dalian Commodities Exchange to warn investors about price volatility and a stockpile of construction rebar that’s running at about twice average seasonal levels, prices are at their best in 12 months and blast furnaces are making good money.

The pandemic-induced weakness in the steel sector outside China is also making it more attractive to pollute. Coking coal, a crucial ingredient in sinter feed, is at some of its lowest levels in years thanks to sluggish demand from India, Japan and South Korea. In recent years it’s typically sold for two or three times the price of iron ore. For the first time since 2014, however, the two commodities are now touching parity. 

So far there’s little sign that Beijing is seeing the pickup in particulate concentrations that typically accompanies a narrowing in the lump premium. That may be largely due to prevailing wind directions keeping pollution locked up in areas of Hebei and Shandong provinces where steelmaking is concentrated.

Over the coming months, steel production is likely to be running full tilt. China’s summer rains and floods are receding, giving construction workers a narrow window of opportunity to get building until October rolls around and winter weather brings more severe, and strictly enforced, steel production curbs — not to mention a possible revival of coronavirus infections.

Pollution has long dogged China’s industrialization, responsible for 1.1 million premature deaths in 2015 alone. Better air quality since then has been a key priority for Beijing, suggesting that quality of life might finally take precedence over growth at all costs.

Chinese politicians have taken pride in the way they’ve managed to largely suppress Covid-19 while getting the economy moving again — but if the price of kick-starting economic growth is a renewed burden of pollution-related fatalities, it’s going to be a distinctly Pyrrhic victory.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

David Fickling is a Bloomberg Opinion columnist covering commodities, as well as industrial and consumer companies. He has been a reporter for Bloomberg News, Dow Jones, the Wall Street Journal, the Financial Times and the Guardian.

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