Clean air regulations reduce hospital admissions in New York

One of the few studies to measure whether air pollution regulations lead to fewer illnesses found they do in most cases. Overall, regional rules required by the federal Clean Air Act helped decrease smog levels across the state of New York during the 3-year period from 2004 – 2006 and resulted in fewer hospital admissions for respiratory illnesses. Compared to a pre-implementation baseline, ozone levels were reduced by up to 9 percent, and hospitalisations were down by as much as 11 percent, depending on the region. These results are consistent with the limited number of other studies that compare pollution levels and health before and after air pollution regulations go into effect. Although air pollution regulations – such as the Clean Air Act in the United States – have been in place for decades, whether they effectively reduce air pollution levels and improve public health is not well understood. One complication is that pollutants generated in one state or region can often migrate with wind and air currents to other areas. Regulated air pollutants include ozone, particulate matter, carbon monoxide, nitrogen oxides (NOx), sulphur dioxide and lead. Ozone, a major part of smog, is known to irritate those with asthma or chronic bronchitis, especially during summer months. Ozone also has been linked with increased hospital admissions for respiratory related illness and even increased risk of death. Both local and regional sources release NOx, which is turned into ozone by sunlight. Most local emissions are from vehicle traffic, while regional sources typically include large facilities, such as coal-burning power plants. Because air pollution moves, cleanup is tricky. If one state tries to reduce the pollution at its source – often at great expense – pollutants can blow in from other places that may not have the same restrictions. To help states meet federal standards, the U.S. Environmental Protection Agency created the NOx Budget Trading Program (NBP). The cap and trade program – which was fully implemented in 2004 – helps 20 eastern states coordinate their efforts and work together to reduce NOx emissions. Yet, the program’s effect on health is not known. In 2008, the NBP program was replaced by the EPA’s Clean Air Interstate Rule (CAIR). During the study, the researchers wanted to know the impacts of the NBP on air pollution – specifically ozone – and health. They examined ozone levels and hospital admissions for respiratory disease in the state of New York before and after the program began. Using data from air monitors across the state, investigators compared summertime ozone concentrations before the program from the years 1997 – 2000 with concentrations after from the years 2004 – 2006. Differences in weather patterns were taken into account. The number of people admitted to hospitals for respiratory illnesses were gathered from a state-wide database. Hospitalisations were compared before and after the NBP. Respiratory hospitalisations for asthma, chronic bronchitis, bronchitis, emphysema and chronic airway obstruction were included for all ages. Among children 0 – 4 acute bronchitis and bronchiolitis were also included. The eight regions studied were Long Island, New York City Metro, Lower Hudson, Upper Hudson, Adirondack, Central, Eastern Lake Ontario, and Western New York. The results were compared by region, urban area, diagnosis, age, race/ethnicity and health insurance group. The results demonstrated that ozone levels for all eight regions in New York were up to 9 percent lower following implementation of NBP. Importantly, substantial reductions were seen in late summer, when ozone levels are often the worst. In four regions, hospital admissions for respiratory illness also decreased. The greatest reduction was 11 percent fewer admissions after NBP compared to before. The biggest drops were in the Lower Hudson (11 percent), Central (10 percent) and New York City metropolitan area (almost 6 percent). However, the result was not consistent. In other regions, hospital admissions for respiratory illness actually increased by nearly 18 percent after NBP. These increases were modest, however, when compared to increases seen for several non-respiratory hospitalisations. For example, hospitalisations for gastroenteritis increased by an average of 67 percent state-wide during this time period. When hospital admissions for specific respiratory illnesses were compared most showed decreases. Admissions for chronic airway obstruction decreased 72 percent and asthma admissions decreased 3 percent, but admissions for chronic bronchitis increased by 9 percent across the whole state. Admissions also decreased for all age groups except those older than 65, which remained constant. For admissions among health insurance groups, Medicaid and Uninsured/Self Pay persons had large reductions in admissions (20 percent and 43 percent reductions respectively). Medicare participants had small reductions and private insurers had a small increase. Similar to ozone levels, the biggest reduction in hospital admissions was seen in late summer. The findings from this study indicate that regulations do work to lower pollution, which in turn can improve respiratory health. Ozone levels decreased across the state of New York and hospital admissions for respiratory disease dipped in half of the regions studied after the EPA’s regulatory program started. There were also notable decreases in hospital admissions for certain respiratory illnesses, most age groups and most health insurance groups. The reduced admissions for those on public assistance suggests that low income residents may have benefited the most from air quality improvements. This would be an important achievement since this group often experiences the highest air pollution exposures. These results are consistent with the limited number of other studies that compare pollution levels and health before and after required air pollution reductions. Since ozone levels decreased across the state, the increases in admissions for respiratory illness observed in some regions are likely due to other factors, which may have stronger effects. These factors could include other air pollutants besides ozone, local variation in air pollutant levels, underlying disease rates or population characteristics such as greater proportions of elderly residents.