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Deaths and disability from cardiovascular disease linked to small particles of air pollution rose by about a third worldwide between 1990 and 2019, a new study says.

Men were affected more than women, and poorer regions more than wealthier ones. And although deaths related to such pollution actually fell after adjusting for age, people are living longer with disability, according to the , published Wednesday in the Journal of the ľ¹ÏÖ±²¥.

Previous research has connected cardiovascular death and disability to particulate matter pollution. Outdoors, such pollution comes from vehicle emissions, wildfire smoke, dust, pollen and soot. Indoors, it can derive from heating or cooking with coal or wood, especially when there is poor ventilation.

Particulate matter may irritate the eyes, nose or throat. Particles can be easily inhaled and reach the lungs and bloodstream. Previous research has associated exposure to fine particulate matter pollution with heart disease, stroke and other health issues.

The researchers analyzed particulate matter pollution as a risk factor for death and disability using data from 204 countries collected in the study. Exposure to pollution was estimated using information from satellite and ground-level monitoring, computer models of chemicals in the atmosphere and land-use data.

"We focused on examining the burden globally because particulate matter pollution is a widespread environmental risk factor that affects all populations worldwide, and understanding its impact on cardiovascular health can help guide public health interventions and policy decisions," Dr. Farshad Farzadfar, the study's senior author, said in a news release. Farzadfar is a professor of medicine in the noncommunicable diseases research center of the Endocrinology and Metabolism Research Institute at Tehran University of Medical Sciences in Iran.

Data from the study examined stroke and ischemic heart disease, which is when blood supply to the heart is blocked, usually by plaque buildup in the arteries.

The researchers analyzed changes over time in cardiovascular disease deaths, years of life lost and years lived with disability because of particulate matter pollution. They also looked at disability-adjusted life years, a measure that considers both the loss of life and the effect on quality of life due to disability. The cardiovascular disease burden was assessed both overall and with statistical adjustments to compare health outcomes across a range of ages.

The analysis found that over the study period, disability-adjusted life years rose by 31% worldwide. The total annual number of deaths from cardiovascular disease attributable to particulate matter air pollution rose to 3.5 million in 2019 from 2.6 million in 1990.

Overall deaths increased 43% among men and 28% among women.

Regions with lower socioeconomic conditions saw more lives lost and fewer years lived with disability as compared with those with higher socioeconomic conditions.

After researchers adjusted for people's age, however, there was a nearly 37% decrease in cardiovascular deaths attributed to particulate matter pollution during the decades studied. "The declines in deaths may be considered positive news, as they indicate improvements in health care, air pollution control measures and access to treatment," Farzadfar said. "However, the increase in disability-adjusted life years suggests that although fewer people were dying from cardiovascular disease, more people were living with disability."

The researchers also found differences related to indoor and outdoor pollution. Age-standardized cardiovascular death and disability attributed to outdoor particulate matter pollution rose by 8%. For household pollution, it fell by 65%.

"The reason for the decrease in the burden of household air pollution from solid fuels might be better access and use of cleaner fuels, such as refined biomass, ethanol, liquefied petroleum gas, solar and electricity," Farzadfar said. Better stoves and ventilation also might have helped.

"The shifting pattern from household air pollution due to solid fuels to outdoor, ambient (particulate matter) pollution has important public policy implications," he said.

The researchers acknowledged limitations. Pollution measures are based on regional estimates and may not accurately reflect individual exposure. And results from this analysis of the association between particulate matter pollution and cardiovascular outcomes may not be generalizable to other health conditions or pollutants.