2019-2021 Ozone Air Quality Data Update In 2015, the 8-hour ozone National Ambient Air Quality Standard (NAAQS) was revised to 0.070 ppm. Based on ozone air quality monitoring data for the three-year period 2019-2021, there are four counties in New England exceeding the revised 8-hour ozone standard. New England Counties 2019-2021 8-hour Ozone Design Values State County 8-hour Ozone Design Value (ppb)1 Connecticut Fairfield 81 Connecticut Hartford 67 Connecticut Litchfield 64 Connecticut Middlesex 74 Connecticut New Haven 82 Connecticut New London 73 Connecticut Tolland 67 Connecticut Windham 65 Maine Androscoggin 53 Maine Aroostook 52 Maine Cumberland 62 Maine Hancock 67 Maine Kennebec 54 Maine Knox 60 Maine Oxford 54 Maine Penobscot 57 Maine Washington 55 Maine York 64 Massachusetts Barnstable 64 Massachusetts Berkshire 59 Massachusetts Bristol 65 Massachusetts Dukes 65 Massachusetts Essex 62 Massachusetts Franklin 55 Massachusetts Hampden 63 Massachusetts Hampshire 63 Massachusetts Middlesex 58 Massachusetts Norfolk 56 Massachusetts Plymouth 60 ------- Massachusetts Suffolk 59 Massachusetts Worcester 62 New Hampshire Belknap 53 New Hampshire Cheshire 54 New Hampshire Coos 57 New Hampshire Grafton 52 New Hampshire Hillsborough 59 New Hampshire Merrimack 56 New Hampshire Rockingham 62 Rhode Island Kent 65 Rhode Island Providence 65 Rhode Island Washington 67 Vermont Bennington 57 Vermont Chittenden 57 Vermont Rutland 53 1 The level of the 2015 8-hour ozone (O3) National Ambient Air Quality Standard (NAAQS) is 0.070 parts per million (ppm). The air quality design value for the 8-hour O3 NAAQS is the 3- year average of the annual 4th highest daily maximum 8-hour average O3 concentrations. The 8-hour O3 NAAQS is not met when the 8-hour design value is greater than 0.070 ppm (70 ppb). ------- |