Arline Geronimus has spent the last 40 years researching racial and class injustice in the US. Her first non-academic book is the culmination of a life’s groundbreaking work. The term “weathering”, which she coined decades ago, is today widely recognised in public health, and refers to the process of chronic social and psychological stress that activates harmful biological processes among people in marginalised communities, ageing their bodies prematurely. She presents a staggering accumulation of evidence to show how daily discrimination grinds people down and all too often leads to debilitating illness and early death.

While the impact of weathering is starkest and most shocking in the health outcomes of Black Americans compared to other communities, the phenomenon transcends race. Only 50% of impoverished white people in Kentucky – from the social group sometimes stereotyped as “hillbillies” – are expected to reach the age of 50 without a “health-induced disability”. It’s a statistic mirrored among Black people living in deprived areas of Chicago. For both, the leading causes of excess deaths are not opioids and gun crime, as the respective cliches might suggest but, rather, chronic issues of the kind associated with weathering: cardiovascular disease and cancer. What these two groups have in common is not simply poverty: it is the fact that they are both viewed with “contempt, fear or resentment” by those around them.

In general, as the epidemiologist Michael Marmot has demonstrated, the richer you are, the healthier you are likely to be. But Geronimus’s research provides an important caveat. People from oppressed or exploited groups can never entirely escape the corrosive reach of weathering, no matter how hard they work, or how successful they become. In fact, the effects of weathering are even more pronounced for those who exercise grit, resilience and determination in the face of prejudice. Geronimus hypothesises that this is because they tend to come in closer contact with bureaucracies and the establishment, and are therefore subject to more frequent micro-aggressions that require “high effort psychosocial coping”.

The research Geronimus cites is frequently jaw-dropping, especially when it demonstrates how people’s health can be affected by one-off events that don’t directly affect their lives but serve to heighten their sense of being rejected by a hostile society. In 2008, there was a brutal militarised immigration raid on a meat-processing plant in Iowa staffed mostly by Mexican and Guatemalan migrants. In the nine months following the raid, rates of low birth weight and premature deliveries in pregnant Latina women soared state-wide, whether they were US or foreign-born. Prior to this period, birth outcomes in this group had been improving. Similar effects were seen in the year after 9/11 in California, among women with Arabic surnames, whether or not they were Muslim.

So far, so depressing. But there are reasons for optimism too, In the year after gay marriage was legalised in Massachusetts, the physical and mental health of gay men significantly improved compared to the year before: hypertension fell by 18%, depression fell by 14% and healthcare costs fell by 15%. Part two of Weathering offers hopeful solutions to health inequities. It is crisp, backed with evidence and rather heroic in spirit. Geronimus sets out five principles for better public policy, including considering biological, social and psychological factors that contribute to inequality, and making sure no decisions are made about people without their involvement. It is the final principle, though, that is most resonant in this extraordinary and timely work, especially in a world for ever altered by Covid-19: recognising that “all our fates are linked”.

• Weathering: The Extraordinary Stress of Ordinary Life in an Unjust Society by Arline Geronimus is published by Virago (£25). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply.